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1
Chan, Tak Ming. "Structural behaviour of elliptical hollow sections." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/11975.
Full textAbstract:
Elliptical hollow sections (EHS) represent the recent addition to the range of tubular structural products. Their distinct closed nature brings structural efficiency by offering differing flexible rigidities about each of the principal axes as well as high torsional stiffness. It also offers an interesting and unusual smooth streamlined appearance which can be utilised to fulfil contemporary streamlined appearance which can be utilised to fulfil contemporary design visions. The varying radius of curvature around the circumference characterises the distinctive structural behaviour of EHS from other tubular sections. In this study, the manifestation of local buckling under compression and in-plane bending about each of the principal axes has been examined, and a system of cross-section classification has been proposed.
2
Bauer, Dominique. "Triangular trusses fabricated from rectangular hollow sections." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75364.
Full textAbstract:
This thesis deals with the behaviour and design of triangular trusses fabricated from Hollow Structural Sections (HSS), with two Warren-type web planes and a single tension chord. Experimental programs are described in which triangular truss segments and simplified joints were tested in order to investigate the behaviour of compression web members and tension-chord welded joints. The mechanics of joint deformations are analysed in relation to the yield line theory, and simple models are shown to give a good prediction of the joint stiffnesses and strengths. Complex yield line models are investigated, but are slightly or not superior to the simple models. Recommendations are established covering the design of tension and compression chord joints, as well as chord and web members. The design of a 22 m span triangular truss is outlined.
3
Ozkan, Istemi Faruk. "Plastic interaction relations for hollow structural steel sections." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6088.
Full textAbstract:
The first part of this study reports an experimental program consisting of six full-scale tests on pipe sections under load combinations of shearing forces, bending moments, and twisting moments. The experimental results agree very well with the predicted failure loads based on recently developed interaction relations. The experimental program establishes the validity of the analytical techniques used to derive the interaction relations for pipe sections. The verified methodology is extended to derive interaction relations for square hollow structural sections under combinations of normal forces, twisting moments, biaxial bending moments, and biaxial shearing forces. Careful consideration is given to the applicability limits of the developed interaction relations. A stress resultant transformation scheme is devised in order to reduce the number of interaction relations from 20 cases to only three fundamental cases.
4
Wilkinson, Timothy James. "The Plastic Behaviour of Cold-Formed Rectangular Hollow Sections." University of Sydney. Department of Civil Engineering, 2000. http://hdl.handle.net/2123/843.
Full textAbstract:
The aim of this thesis is to assess the suitability of cold-formed rectangular hollow sections (RHS) for plastic design. The project involved an extensive range of tests on cold-formed Grade C350 and Grade C450 (DuraGal) RHS beams, joints and frames. A large number of finite element analyses was also carried out on models of RHS beams. The conclusion is that cold- formed RHS can be used in plastic design, but stricter element slenderness (b/t) limits and consideration of the connections, are required. Further research, particularly into the effect of axial compression on element slenderness limits, is required before changes to current design rules can be finalised. Bending tests were performed on cold-formed RHS to examine the web and flange slenderness required to maintain the plastic moment for a large enough rotation suitable for plastic design. The major conclusions of the beam tests were: (i) Some sections which are classified as Compact or Class 1 by current steel design specifications do not maintain plastic rotations considered sufficient for plastic design. (ii) The current design philosophy, in which flange and web slenderness limits are independent, is inappropriate. An interaction formula is required, and simple formulations are proposed for RHS. Connection tests were performed on various types of knee joints in RHS, suitable for the column - rafter connection in a portal frame. The connection types investigated were welded stiffened and unstiffened rigid knee connections, bolted plate knee joints, and welded and bolted internal sleeve knee joints, for use in RHS portal frames. The ability of the connections to act as plastic hinges in a portal frame was investigated. The most important finding of the joint tests was the unexpected fracture of the cold-formed welded connections under opening moment before significant plastic rotations occurred. The use of an internal sleeve moved the plastic hinge in the connection away from the connection centre- line thus eliminating the need for the weld between the RHS, or the RHS and the stiffening plate, to carry the majority of the load. The internal sleeve connections were capable of sustaining the plastic moment for large rotations considered suitable for plastic design. Tests on pinned-base portal frames were also performed. There were three separate tests, with two different ratios of vertical to horizontal point loads, simulating gravity and horizontal wind loads. Two grades of steel were used for comparison. The aims of the tests were to examine if a plastic collapse mechanism could form in a cold-formed RHS frame, and to investigate if plastic design was suitable for such frames. In each frame, two regions of highly concentrated curvature were observed before the onset of local buckling, which indicated the formation of plastic hinges and a plastic collapse mechanism. An advanced plastic zone structural analysis which accounted for second order effects, material non-linearity and member imperfections slightly overestimated the strength of the frames. The analysis slightly underestimated the deflections, and hence the magnitude of the second order effects. A second order plastic zone analysis, which did not account for the effects of structural imperfections, provided the best estimates of the strengths of the frames, but also underestimated the deflections. While cold-formed RHS did not satisfy the material ductility requirements specified for plastic design in some current steel design standards, plastic hinges and plastic collapse mechanisms formed. This suggests that the restriction on plastic design for cold-formed RHS based on insufficient material ductility is unnecessary, provided that the connections are suitable for plastic hinge formation, if required. A large number of finite element analyses were performed to simulate the bending tests summarised above, and to examine various parameters not studied in the experimental investigation. To simulate the experimental rotation capacity of the RHS beams, a sinusoidally varying longitudinal local imperfection was prescribed. The finite element analysis determined similar trends as observed experimentally, namely that the rotation capacity depended on both the web slenderness and flange slenderness, and that for a given section aspect ratio, the relationship between web slenderness and rotation capacity was non-linear. The main finding of the finite element study was that the size of the imperfections had an unexpectedly large influence on the rotation capacity. Larger imperfections were required in the more slender sections to simulate the experimental results. There should be further investigation into the effect of varying material properties on rotation capacity.
5
Qiu, Wei. "Beam-column behaviour of concrete-filled elliptical hollow sections." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/48035.
Full textAbstract:
Concrete filled elliptical hollow sections (CFEHS) are a relatively new addition to the range of composite cross-sections available to structural engineers. The European design code EN 1994-1-1 (BSI, 2004) provides design rules for composite cross-sections, including concrete filled circular hollow sections (CFCHS) and concrete filled rectangular sections (CFRHS), but CFEHS are not considered in the present design code. In order to contribute to the development of design provisions for CFEHS, a comprehensive experimental and numerical study of their column and beam-column behaviour has been carried out. The testing programme covered a range of member lengths, reinforcement ratios and loading eccentricities and consisted of 27 column and beam-column member tests, 70 concrete cylinder compression tests, 3 reinforcing bar tensile tests and 2 steel tube tensile coupon tests. Numerical models were developed using the nonlinear finite element package Abaqus and validated against the experimental results. Using the validated models, detailed numerical parametric studies of CFEHS members have been conducted addressing three different scenarios: (1) members under axial compression, (2) members under combined axial compression and uniaxial bending and (3) members under combined axial compression and biaxial bending. Based on the combined test and numerical data set, along with previous experimental results reported in the literature, new design rules for CFEHS are proposed. It is shown that the current provisions of EN 1994-1-1 (BSI, 2004) for the design of CFCHS and CFRHS are appropriate for the design of members of elliptical cross-section, using either buckling curve b or c, depending on the level of steel reinforcement for members under axial compression. Cross-section axial load-moment (N-M) interaction curves are generally employed for the design of composite members under combined loading. A numerical approach, developed in Matlab, was used to the generate the N-M interaction diagram for CFEHS, which was found to offer a suitable design basis to be used in conjunction with calculated axial forces and second-order moments. Finally, an assessment of the reliability of the design proposals for CFEHS columns and beam-columns in accordance with Annex D of EN 1990 (BSI, 2002) was carried out.
6
Nowzartash, Farhood. "Plastic Interaction Relations for Elliptical and Semi-Elliptical Hollow Sections." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20042.
Full textAbstract:
The advancement of the structural steel manufacturing industry has led to the recent emergence of steel members with Elliptical Hollow Sections (EHS) and Semi Elliptical Hollow Sections (SEHS). Although these sections are gaining popularity among architects, the lack of design guidelines specifically tailored towards these sections inhibits their efficient structural use. Within this context, this thesis provides several steps towards the development of such guidelines.
A review of the manufacturing process of hot-rolled steel sections is conducted with emphasis on hollow structural sections. The main factors affecting the formation of residual stresses during cooling of the sections are discussed.
Lower bound plastic interaction relations for EHS subjected to combinations of axial force, bi-axial bending moments and torsion are then derived. The formulation is based on the lower bound theorem of plasticity and the maximum distortional energy density yield criterion. Its applicability for conducting the cross-sectional interaction check in structural steel design problems is illustrated through a practical example. A simplified and conservative interaction equation is then proposed based on curve fitting of the results of the lower bound solution.
Upper bound interaction relations are next developed for EHS subjected to combinations of axial force, bi-axial bending moments, torsion and bimoments. The formulation is based on kinematically admissible strain fields within the context of the upper bound theorem of plasticity. The interaction relations derived successfully capture the effect of confining radial strains present at welded end sections, as well as sections that are free to deform in the radial direction away from end welded sections. An iterative solution technique is developed to solve the resulting highly non-linear system of interaction relations.
The effects of residual stresses and initial imperfections on axial compressive resistance of hot-rolled EHS are then incorporated into the lower bound interaction relations. Towards that goal, the thermo-mechanical properties of steel were extracted from the literature. A thermo-mechanical finite element model was developed for prediction of residual stresses in rolled sections. The validity of the model was assessed by comparison against residual stress measurements available in the literature. The model is then applied to predict the residual stresses in hot-rolled EHS.
A series of geometric and material nonlinear finite element analyses is conducted on columns of EHS sections. The analyses include predicted residual stresses and initial out-of-straightness imperfections in order to determine the inelastic buckling capacity of EHS members and generate column curves for EHS sections. The column curves are subsequently compared to those based on Canadian, American and European design codes. Two column curve equations are proposed in a format similar to that of the Canadian Standards for buckling about major and minor axes. The column curves were subsequently combined with the interaction relations developed to provide design rules for EHS members under combined loads.
The last contribution of the thesis provides a formulation of lower bound interaction relations for SEHS subject to combinations of axial force, bi-axial bending moments and torsion. An iterative scheme for solving the parametric form of the interaction relations is developed and a grid of admissible stress resultant combinations is generated. A series of trial functions are fitted to the grid of internal force combinations and two simplified and conservative interaction equations are proposed.
7
Ian, Ferreira. "Designing power line towers using circular hollow sections / Ian Ferreira." Thesis, North-West University, 2013. http://hdl.handle.net/10394/8737.
Full textAbstract:
It has become a challenging exercise to obtain land in order to further develop
the electrical infrastructure in South Africa. The reason for this is that high
voltage transmission towers visually impacts the surroundings and require a
large servitude in order to accommodate these structures. The requirements
for low visible towers with small foundation footprints may be achieved with
double circuit power line towers.
However, the structural loading in tower member's increase drastically
as a result of large conductor bundles, higher reliability, smaller foundation
footprints and a increase in wind loading because of the taller structures.
This limits the further economical use of standard angular hot rolled sections
and requires that alternative cross sections are considered in the design
of power line towers.
The aim of this research is to focus on the practical and cost-e ective
implementation of circular hollow sections (CHS) in power line towers. The
design of a power line system consist of a family of tower structures which
include a large number of structural and non-structural members as well as
many connections resisting various combinations of loads. The outcome of
this research proves that a feasible and practical way exist to implement
circular hollow sections in power line tower design using current design software,
current design standards and current manufacturing techniques for
South African conditions.
It is recommended that connections between tower elements should be
similar to existing connection practices where possible. This will reduce the
requirements for specialized software or connection standards. This will also
facilitate the design of hybrid tubular and angular member towers. Hence a
review of current angular member and connection design practices are given
for the reader. Before the design of a tubular power line tower may be done, various
hollow section connections and stability criteria are reviewed. The CIDECT
manuals provide an excellent resource for hollow section connections for static
and dynamic conditions. It is important to note that it is not the intention
of the author to question or improve on the existing hollow section design
formulae, but rather to show their ease of implementation in the power line
industry.
A tubular tower was designed and fabricated in order to combine the theory
and practical implementation thereof. In the design of this test tower,
the author introduced a novel cross arm design. The new con guration cross
arm has only three main chords compared with the conventional cross arm
with four main chords. It is envisaged that this new cross arm con guration
will reduce overall tower cost as well as construction cost.
An analytical and numerical structural analysis was used to design the
test tower. An isolated analysis was also performed on the tower cross arm in
order to compare and validate the use of less expensive structural software.
The comparison considered a full nite element analysis (ANSYS) compared
with a beam element analysis (Prokon). The results show that there is an
excellent correlation between the two models given that speci c, yet simple
modeling techniques are used to model the tower elements.
In order to conclude the validity of the recommended design approach
and the integrity of the test structure, physical testing was done at the Eskom
tower test facility. The structure was securely xed to the base of the
test bed and strain gauges were tted on several of the tower members. Steel
wire ropes with load cells were tted to the cross arms of the structure and
three typical load cases were evaluated.
Comparing the physical test results with the Prokon model, a 10% variation
between member loads were recorded. The loads in the test tower was
in most cases higher compared with the Prokon model.
In summary, the design process proposed here may successfully be used
to design and manufacture CHS power line towers. The design process uses
current design software, current design standards and current manufacturing
techniques.
Further investigation on full scale structures are required in order to study
the economics of tubular towers versus angular member towers. This study should include fabricators and construction experts in order to comprehend
the impact on the power-line industry. The author suspects that the fabrication
cost of CHS towers will be slightly higher but the construction cost
will be signi cantly less.Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013
8
Roodbaraky, K. "Finite element modelling of tubular cross joints in rectangular hollow sections." Thesis, University of Nottingham, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384702.
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9
Rush, David Ian. "Fire performance of unprotected and protected concrete filled steel hollow structural sections." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8298.
Full textAbstract:
Concrete filled steel hollow structural (CFS) sections are increasingly used to support large compressive loads in buildings, with the concrete infill and the steel tube working together to yield several benefits both at ambient temperature and during a fire. These members are now widely applied in the design of highly optimized multi-storey and high rise buildings where fire resistance ratings of two or more hours may be required. Whilst the response and design of these sections at ambient temperatures is reasonably well understood, their response in fire, and thus their fire resistance design, is less well established. Structural fire resistance design guidance is available but has been developed based on tests of predominantly short, concentrically-loaded, small-diameter columns in braced frames using normal strength concrete. The current prescriptive guidance is limited and the design of CFS columns is thus often based on a detailed performance based approach, which can be time consuming and expensive and which is generally not well supported by a deep understanding of CFS columns’ behaviour in real fires. This thesis aims to understand the fundamental thermal and mechanical factors at play within these sections so as to provide guidance on how to improve their design for fire resistance when applied either as unprotected or protected sections. A meta-analysis of available furnace test data is used to demonstrate that current guidance fails to capture the relevant mechanics and thus poorly predicts fire resistance. It is also demonstrated that the predictive abilities of the available design standards vary with physical characteristics of the CFS section such as shape and size. A factor which has been observed in furnace tests on CFS sections but which is not accounted for in available guidance is the formation of an air gap between the steel tube and the concrete core due to differential expansion; this affects their structural response in fire. The insulating effect of air gap formation has not previously been addressed in literature and an experimental program is presented to systematically assess the effects of a gap on the heat transfer through the section; showing that the presence of even a 1 mm gap is important. To explicitly assess the heat transfer response within both unprotected and fire protected (i.e. insulated) CFS sections, 34 large scale standard furnace tests were performed in partnership with an industry sponsor. Fourteen tests on large scale unloaded unprotected CFS sections are presented to assess current capability to predict the thermal response and to assess the effects of different sectional and material parameters on heating. New best practice thermal modelling guidance is suggested based on comparison between the models and observed temperatures from the tests. Twenty CFS specimens of varying size and shape, protected with different types and thicknesses of intumescent paint fire insulation, were also tested unloaded in a furnace to understand the thermal evolution within protected CFS sections and to develop design guidance to support application of intumescent coatings in performance based fire resistance design of CFS sections. These tests demonstrate that the intumescent coatings were far more effective than expected when applied to CFS sections, and that current methods of designing the coatings’ thickness are overly conservative. The reason for this appears to be that the calculation of effective section factor which is used in the prescription of intumescent coating thicknesses is based on the thermal response of unprotected CFS sections which display fundamentally different heating characteristics from protected sections due to the development of a thermal gradient in the concrete core. It is also demonstrated (by calculation supported by the testing presented herein) that the steel failure temperature (i.e. limiting temperature) of an unprotected CFS column in fire is significantly higher than one which is protected; procedures to determine the limiting temperature of protected sections are suggested. Finally, the residual strength of fire-exposed CFS columns is examined through structural testing of 19 of the 34 fire tested columns along with unheated control specimens. The results provide insights into the residual response of unprotected and protected CFS section exposed to fire, and demonstrate a reasonable ability to calculate their residual structural capacity. The work presented in this thesis has shed light on the ability of available guidance to rationally predict the thermal and structural response to fire of CFS columns, has improved the understanding of the thermal evolution within protected and unprotected CFS sections in fire, has provided best-practice guidance and material input parameters for both thermal and structural modelling of CFS sections, and has improved understanding of the residual capacity of CFS sections after a fire.
10
Buchanan, Craig. "Testing and design of conventional and novel stainless steel hollow structural sections." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/49208.
Full textAbstract:
The topic of this thesis is the testing and design of conventionally formed and additive manufactured stainless steel hollow structural sections. Although design codes currently exist for stainless steel hollow structural elements, the provisions are based on limited structural data and therefore require further evaluation for their suitability, and are not intended to apply to additive manufactured elements. Focussing on conventionally formed circular hollow sections (CHS), the existing design provisions have been carefully reappraised based on a dataset of tests and finite element results generated in this study and existing tests collected from the literature. In total, 37 concentrically loaded column tests, 26 beam-column tests and 10 stub column tests have been undertaken on austenitic, duplex and ferritic stainless steel CHS. The experimental data has been supplemented with over 2400 finite element case studies. The reappraisal highlighted that there is additional capacity to be sought at the cross-section level for pure compression, bending and combined loading, and at the member level for beam-columns, but the current CHS flexural buckling provisions were found to be unconservative for certain global slenderness values. Based on these observations, revised design rules have been proposed. Additive manufactured sections, not currently covered by structural design standards, have also been investigated. An experimental programme consisting of 28 tensile coupon tests, 14 compressive coupon tests and 5 square hollow section (SHS) stub column tests has been undertaken. The initial results indicate general applicability of existing design standards to these new novel sections.
11
Shahanara, Kaniz. "Bond strength of steel hollow sections using carbon fibre reinforced polymer composites." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/62338/1/Kaniz_Shahanara_Thesis.pdf.
Full textAbstract:
This research was a step forward in developing bond strength of CFRP strengthened steel hollow sections under tension loads. The studies have revealed the ultimate load carrying capacity of the CFRP strengthened steel hollow sections and the stress distribution for different orientations of the CFRP sheet at different layers. This thesis presents a series of experimental and finite element analysis to determine a good understanding of the bond characteristics of CFRP strengthened steel hollow sections.
12
Barnett, Tobias C. "Assessment of clamping behaviour of a newly developed blind bolt, and an investigation into its performance in the tension region of moment resisting connections using open and hollow sections." Thesis, Nottingham Trent University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366362.
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13
Saket, Hassan Khalil. "The fatigue behaviour of fillet welded joints of plates and square hollow sections." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281213.
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14
Elamin, Ahmed Mohamed Elamin Ahmed. "The face bending behaviour of blind-bolted connections to concrete-filled hollow sections." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/13938/.
Full textAbstract:
Structural Hollow Sections have superior structural performance over open sections and are currently available as circular, elliptical or rectangular sections. However, the practical use of these sections is limited due to complexities involved in their connections. The lack of access to the interior of the section makes it almost impossible to use standard bolted connections. The so-called Blind Bolts are therefore used as fasteners to alleviate these complexities by allowing for bolted rather than, the-not-so-popular, welded connections to hollow sections. Lindapter’s Hollo-Bolt is one of the Blind Bolts used for hollow sections connections. However its established use is currently restricted to transferring tensile forces and vertical shear only. Filling Square Hollow Sections (SHS) with concrete, when utilising Hollo-Bolts, was found to improve the connections’ performance in resisting moments, but there is currently no guidance available for the design of such connections. Many methods are used to model connections behaviour. The so-called component method has emerged to be the most favourite and has been adopted in the Eurocode 3. In this method, the connection is divided into basic components. Each component has a contribution to the structural behaviour of the connection. For Hollo-Bolted moment resisting connections, the behaviour of two of the components, fastener in tension and concrete-filled SHS face in bending, are not available. The application of the component method is therefore not possible. This research aims to devise a model to predict the behaviour of the concrete-filled SHS face in bending. A novel analytical model of the concrete-filled SHS face bending has been proposed in this work. The model has three parts: Initial Stiffness, Yield Force and Post-Yield Stiffness. The Initial Stiffness was formulated by theoretically substituting the face of the concrete-filled SHS with a beam element. The beam is assumed to be loaded by a rigid strip and fixed at its ends. Yield line analysis was used to investigate possible failure mechanisms and associated strengths. The model adopted the mechanism which theoretically led to the critical yield force. The Post-Yield Stiffness was taken as a percentage of the Initial Stiffness in line with other work from the literature. An extensive full-scale experimental programme was undertaken to calibrate the aforementioned analytical model, and to examine the effects of varying parameters on the SHS face bending behaviour. Typical experiments involved one row of two bolts pulled out of concrete-filled SHS. A special dummy bolts were manufactured to the exact size and geometry of open Hollo-Bolts, and were used in the experimental programme to remove the influence of any deformation associated with the real Hollo-Bolts, and thus isolate the face bending behaviour. Non-contact video-based equipment was used to record the SHS face deformation. Three parameters were varied: the SHS face slenderness ratio, the bolts gauge to SHS width ratio and the concrete in-fill compressive strength. A finite element model was also developed to complement the experimental programme. The model was developed using the ANSYS Parametric Design Language (APDL) to allow for easy parametric analysis and knowledge transfer. Dimensions, parameters and materials properties could be easily altered in the fully parametric model script. The outcomes of the experimental programme and the finite element model were used to formulate design charts for two calibration factors: kis for the calculation of Initial Stiffness, kyf for the calculation of Yield Force. A chart was also formulated for the Post-Yield stiffness ratio. The proposed analytical model (semi-analytical after calibration) was compared with the results of experimental programme and finite element modelling. The model was found to capture the behaviour of concrete-filled SHS face bending with sufficient accuracy, lying between 90% prediction lines derived from the experimental results. This is considered sufficient for the proposed model to capture the concrete-filled SHS face bending component for connection design purposes.
15
Zhao, Wen-Bin. "Behaviour and design of cold-formed steel hollow flange sections under axial compression." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16909/1/Wen-Bin_Zhao_Thesis.pdf.
Full textAbstract:
The use of cold-formed steel structures is increasing rapidly around the world due to the many advances in construction and manufacturing technologies and relevant standards. However, the structural behaviour of these thin-walled steel structures is characterised by a range of buckling modes such as local buckling, distortional buckling or flexural torsional buckling. These buckling problems generally lead to severe reduction and complicated calculations of their member strengths. Therefore it is important to eliminate or delay these buckling problems and simplify the strength calculations of cold-formed steel members.
The Hollow Flange Beam with two triangular hollow flanges, developed by Palmer Tube Mills Pty Ltd in the mid-1990s, has an innovative section that can delay the above buckling problems efficiently. This structural member is considered to combine the advantages of hot-rolled I-sections and conventional cold-formed sections such as C- and Z-sections (Dempsey, 1990). However, this structural product was discontinued in 1997 due to the complicated manufacturing process and the expensive electric resistance welding method associated with severe residual stresses (Doan and Mahendran, 1996). In this thesis, new fastening methods using spot-weld, screw fastener and self-pierced rivet were considered for the triangular Hollow Flange Beams (HFBs) and the new rectangular hollow flange beams (RHFBs). The structural behaviour of these types of members in axial compression was focused in this research project. The objective of this research was to develop suitable design models for the members with triangular and rectangular hollow flanges using new fastening methods so that their behaviour and ultimate strength can be predicted accurately under axial compression.
In the first stage of this research a large number of finite element analyses (FEA) was conducted to study the behaviour of the electric resistance welded, triangular HFBs (ERW-HFBs) under axial compression. Experimental results from previous researchers were used to verify the finite element model and its results. Appropriate design rules based on the current design codes were recommended. Further, a series of finite element models was developed to simulate the corresponding HFBs fastened using lap-welds (called LW-HFBs) and screw fasteners or spot-welds or self-piercing rivets (called S-HFBs). Since the test specimens of LW-HFBs and S-HFBs were unavailable, the finite element results were verified by comparison with the experimental results of ERW-HFB with reasonable agreement.
In the second stage of this research, a total of 51 members with rectangular hollow flanges including the RHFBs made from a single plate and 3PRHFBs made from three plates fastened with spot-welds and screws was tested under axial compression. The finite element models based on the tests were then developed that included the new fasteners, contact simulations, geometric imperfections and residual stresses. The improved finite element models were able to simulate local buckling, yielding, global buckling and local/global buckling interaction failure associated with gap opening as agreed well with the corresponding full-scale experimental results. Extensive parametric studies for the RHFBs made from a single plate and the 3PRHFBs made from three plates were undertaken using finite element analyses. The analytical results were compared with the predictions using the current design rules based on AS 4100, AS/NZS 4600 and the new direct strength method. Appropriate design formulae based on the direct strength method for RHFBs and 3PRHFBs were developed. This thesis has thus enabled the accurate prediction of the behaviour and strength of the new compression members with hollow flanges and paved the way for economical and efficient use of these members in the industry.
16
Zhao, Wen-Bin. "Behaviour and design of cold-formed steel hollow flange sections under axial compression." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16909/.
Full textAbstract:
The use of cold-formed steel structures is increasing rapidly around the world due to the many advances in construction and manufacturing technologies and relevant standards. However, the structural behaviour of these thin-walled steel structures is characterised by a range of buckling modes such as local buckling, distortional buckling or flexural torsional buckling. These buckling problems generally lead to severe reduction and complicated calculations of their member strengths. Therefore it is important to eliminate or delay these buckling problems and simplify the strength calculations of cold-formed steel members.
The Hollow Flange Beam with two triangular hollow flanges, developed by Palmer Tube Mills Pty Ltd in the mid-1990s, has an innovative section that can delay the above buckling problems efficiently. This structural member is considered to combine the advantages of hot-rolled I-sections and conventional cold-formed sections such as C- and Z-sections (Dempsey, 1990). However, this structural product was discontinued in 1997 due to the complicated manufacturing process and the expensive electric resistance welding method associated with severe residual stresses (Doan and Mahendran, 1996). In this thesis, new fastening methods using spot-weld, screw fastener and self-pierced rivet were considered for the triangular Hollow Flange Beams (HFBs) and the new rectangular hollow flange beams (RHFBs). The structural behaviour of these types of members in axial compression was focused in this research project. The objective of this research was to develop suitable design models for the members with triangular and rectangular hollow flanges using new fastening methods so that their behaviour and ultimate strength can be predicted accurately under axial compression.
In the first stage of this research a large number of finite element analyses (FEA) was conducted to study the behaviour of the electric resistance welded, triangular HFBs (ERW-HFBs) under axial compression. Experimental results from previous researchers were used to verify the finite element model and its results. Appropriate design rules based on the current design codes were recommended. Further, a series of finite element models was developed to simulate the corresponding HFBs fastened using lap-welds (called LW-HFBs) and screw fasteners or spot-welds or self-piercing rivets (called S-HFBs). Since the test specimens of LW-HFBs and S-HFBs were unavailable, the finite element results were verified by comparison with the experimental results of ERW-HFB with reasonable agreement.
In the second stage of this research, a total of 51 members with rectangular hollow flanges including the RHFBs made from a single plate and 3PRHFBs made from three plates fastened with spot-welds and screws was tested under axial compression. The finite element models based on the tests were then developed that included the new fasteners, contact simulations, geometric imperfections and residual stresses. The improved finite element models were able to simulate local buckling, yielding, global buckling and local/global buckling interaction failure associated with gap opening as agreed well with the corresponding full-scale experimental results. Extensive parametric studies for the RHFBs made from a single plate and the 3PRHFBs made from three plates were undertaken using finite element analyses. The analytical results were compared with the predictions using the current design rules based on AS 4100, AS/NZS 4600 and the new direct strength method. Appropriate design formulae based on the direct strength method for RHFBs and 3PRHFBs were developed. This thesis has thus enabled the accurate prediction of the behaviour and strength of the new compression members with hollow flanges and paved the way for economical and efficient use of these members in the industry.
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Al-Mughairi, Ali Saud. "The behaviour of moment resisting connection to concrete filled hollow sections using extended hollobolts." Thesis, University of Nottingham, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523005.
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Gkantou, Michaela. "Response and design of high strength steel structures employing square and rectangular hollow sections." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7522/.
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The application of high strength steels (HSS) in the construction industry can lead to more economic design and profound sustainability benefits. To facilitate their use in modern practice, most international structural design codes have included HSS within their contents. Due to limited test data at the time of publishing, HSS design provisions are largely based on those for mild steel, with some restrictions, due to HSS’s inferior ductility and strain-hardening characteristics. Hence, further investigation on the applicability of such design specifications to HSS is required. To this end, within the present research work the structural performance of high strength steel structures employing square and rectangular hot-finished hollow sections is rigorously investigated. Meticulously generated finite element models of individual structural components are validated against test data and subsequently used for the generation of additional structural performance data through the execution of parametric studies. Implementing the aforementioned methodology, focus is also placed upon the structural performance of HSS trusses, whilst the possibility of applying prestress to them to enhance their behaviour is examined. Based on the obtained results, the suitability of current codified design methods to HSS is assessed and appropriate design recommendations are made.
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Ridley-Ellis, Daniel. "Rectangular hollow sections with circular web openings : fundamental behaviour in torsion, bending and shear." Thesis, University of Nottingham, 2000. http://researchrepository.napier.ac.uk/Output/8229.
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The primary aim of the project was to develop the basis for a set of rules to be used in the design of RHS slim floor edge beams with web openings. However, since the research is fundamental in nature, the findings are also applicable to other situations where it may be advantageous to cut holes in load bearing tubular members of rectangular cross-section. The study considered the influence of the number and size of holes upon resistance and stiffness in bending, shear, and torsion and combined analytical Finite Element modelling with large and small scale pseudo-static (short-time static loading) laboratory testing. In all but one category of tests (see below), good agreement was achieved between experimentally measured quantities (such as capacities, deflections and strains) and the corresponding Finite Element predictions, allowing parametric investigations to be conducted with calibrated analytical models. Preliminary design recommendations are presented based on the results of the parametric study and laboratory tests. The design advice was developed with regard to existing recommendations for the design of perforated I-beams, and was produced in a form that allows integration with modern limit state design codes. Aspects of behaviour requiring further investigation have been identified and categorised. Torsion tests on full scale RHS without web openings yielded some unexpected results. Elastic and plastic capacities measured in the laboratory were significantly lower (12–20%) than those predicted by the Finite Element models and the thick walled torsion theory used as the basis of the British and European design procedures. Attempts were made to determine the cause of this behaviour and a number of possibilities were eliminated. Although the anomalous results have not been fully explained, evidence of similar behaviour in previous full-scale testing was discovered.
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Cai, Chao. "Analytical solutions for residual stresses in cold-formed steel circular hollow sections due to cold rolling." Thesis, University of Macau, 2009. http://umaclib3.umac.mo/record=b2148262.
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Öhman, Kristoffer. "The Crocodile Nose Connection : Design and laboratory tests on a novel connection for structural hollow sections." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-67506.
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The great properties and clear form makes the circular hollow section (CHS) appreciated by architects. When connecting these sections today it is common to use gusset plates. The knifeplate connection where the gusset plate is inserted into a slot made at the end of a circular section, is the most used connection today. This type of connections is not seen as aesthetically pleasingby architects because of its abrupt cut of the CHS. An alternative for the knife-plate connection is the Crocodile nose connection (CN-connection). The benefits of the CN-connection is the absence of the abrupt cut and the protruding gusset plate, which makes it appreciated by architects. In this connection the CHS’s ends are tapered, which creates two semi-elliptical cuts at both sides of the member. On these cuts, appropriate plates arefillet welded. These plates are shaped and bended so that when they are welded in place, the orientation of the extending part is parallel to the member axis. A gap is made between the extending parts so that a gusset plate can be inserted and bolted together with the member. Four different specimens of the CN-connection are tested in order to find the best shape. Two specimens have a stiffener between the plates, at a small distance from the end of the CHS. The difference between the presence of a stiffener and the lack of it, is investigated. The results showed that the specimens with the connecting piece obtained a much higher ultimate load, up to 413 %higher. Two different angles of the CHS’s cut is also investigated in order to see the most appropriate bevelling angle. In this case the results showed that the specimens with the smaller bevelling angle obtained a higher ultimate load, up to 40 % higher. A check of the weld connecting the plates and the CHS is also performed. This check was made with an assumed calculation model. The results showed that the calculation model only was valid for the specimens without the connecting piece. The calculation model must therefore be enhanced, in order to work for all dimensioning cases.De goda egenskaperna och den ideala formen gör det cirkulära tvärsnittet uppskattat av arkitekter. Vid anslutningar av dessa tvärsnitt är det idag vanligt att använda knutplåtar. Kniv-plåtanslutningar där knutplåten förs in i en öppning i änden av det cirkulära tvärsnittet är det mest använda förbandet idag. På grund av rörets abrupta slut i detta förband är det inte estetiskt tilltalande enligt arkitekter. Ett alternativ för kniv-plåt-förbandet är Crocodile Nose-förbandet (CN-förbandet). Fördelarna med CN-förbandet är frånvaron av det abrupta slutet och den utstickande knutplåten, vilket görden uppskattad av arkitekter. I detta förband är det cirkulära tvärsnittets kanter nerfasade, vilket skapar två semielliptiska skärytor på båda sidor av röret. På dessa skärytor svetsas lämpliga plåtar med kälsvetsar. Plåtarna är formade på ett sådant sätt att när de är svetsas på plats är orienteringen av den utstickande delen parallel med rörets axel. Ett mellanrum mellan de utstickande delarna skapas så att knutplåten kan föras in och bultas fast tillsammans med röret. Fyra olika provkroppar av CN-förbandet testas för att hitta den bästa utformningen. Tvåprovkroppar har en avstyvning mellan plåtarna. Skillnaden mellan närvaron av avstyvningen och frånvaron av den är undersökt. Resultaten visade att provkropparna med avstyvningen fick enmarkant högre brottlast, upp till 413 % högre. För att även hitta den optimala vinkeln på skärytan har två olika vinklar undersökts. I detta fall visade resultaten att provkropparna med den mindrevinkeln gav en högre brottlast, upp till 40 % högre. Även en kontroll på svetsen som binder ihopplåtarna med röret är gjord. Denna kontroll gjordes med hjälp av en antagen beräkningsmodell.Resultatet visade att beräkningsmodellen endast är giltig för provkropparna utan avstyvningen.Beräkningsmodellen måste därför utvecklas, så den kan användas för samtliga dimensioneringsfall.
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Lucassen, Mattheüs. "Infuence of the modelling of truss joints made of hollow tube sections in finite element models." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263912.
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Several boom segments form the crane boom. These segments are often truss structures formed out of circular hollow sections, which are welded together forming the truss joints. A adequate modelling of these truss joints is very important for operational strength and life. Due to the large boom sizes, efficient models are used in the finite element method, generally built of beam elements. These models have problems capturing the proper bending moments working in the truss joints. This is caused by a insufficient portrayal of the joint stiffness. In the literature several modelling techniques with beam elements are proposed, which capture the joint stiffness better. These different modelling methods are implemented in a parametric boom section and compared with a shell element FE model. From this comparison the most appropriate modelling method is selected, which improve the portrayal of internal loads and nominal stresses. With these improved nominal stress values, it is investigated to implement a different fatigue assessment. The structural stress can be calculated from the nominal stress in combination with stress concentration factor (SCF) equations. To implement the structural stress method as fatigue assessment, several modelling and extrapolation methods have been compared. Which lead to a method for evaluating the structural stress in a efficient matter. This method is compared with existing SCF K truss joint equations, from which a new set of SCF equations is derived. These equations are constructed from a larger dataset, hold a wider validity range and fit better with the FE models. When applying these SCF equations with the improved beam modelling method in a boom section, the structural stress is not adequately captured. This is caused by unsymmetrical stressed braces in the K truss joints. Both the modelling methods and SCF equations account for uniformly stressed braces forming the truss joints. More research needs to be conducted to this uneven behaviour. If the structural stress method needs to be implemented with efficient FE models, submodels out of shell elements combined with beam elements are recommended. For fatigue evaluation with the nominal stress method, beam models which account for the local joint flexibility give sufficient realistic results.Flera kranarmsegment bildar kranarmen. Dessa segment är ofta fackverk utformade av cirkulära ihåliga profiler, som är sammansvetsade och bildar fackverkslederna. En ordentlig modellering av dessa fackförband är mycket viktig för dess driftsstyrka och livslängd. På grund av storleken används finita elementmetoden, vanligtvis uppbyggt av balkelement. Dessa modeller har problem med att beräkna de korrekta böjmomenten som uppstår i fackverkslederna. Detta orsakas av en otillräcklig beskrivning av ledstyvheten. I litteraturen föreslås flera modelleringstekniker med balkelement som tar hänsyn till ledens styvhet bättre. Dessa olika modelleringsmetoder implementeras i en parametrisk kranarmsektion och jämförs med en FE-modell med skalelement. Med denna jämförelse väljs den mest lämpliga modelleringsmetoden, vilket bör förbättra skildringen av interna belastningar och nominella spänningar. Med dessa förbättrade nominella spänningsvärden, undersöks det att genomföra en annan utmattningsbedömning. Den strukturella spänningen kan beräknas utifrån den nominella spänningen i kombination med spänningskoncentrationsfaktor- (SCF) ekvationerna. För att implementera strukturella spänningsmetoden som utmattningsbedömning, har flera modellerings- och extrapoleringsmetoder jämförts. Detta leder till en metod för att utvärdera den strukturella spänningen effektivt. Denna metod jämförs med befintliga SCF-ekvationer, från vilka en ny uppsättning SCF-ekvationer härleds. Dessa ekvationer är konstruerade från en större datauppsättning, har ett bredare giltighetsområde och passar bättre med FE-modellerna. När man applicerar dessa SCF-ekvationer med den förbättrade balkmodelleringsmetoden i en kranarmsektion, uppsamlas strukturella spänningar inte tillräckligt, detta orsakas av ojämna spänningar i diagonalelementen i fackverkslederna. Både modelleringsmetoderna och SCF-ekvationerna tar hänsyn till jämnt spända diagonalelement som uppstår i fackverkslederna. Mer forskning bör göras över detta ojämna beteende. Om den strukturella spänningsmetoden måste implementeras med effektiva FE-modeller, rekommenderas undermodeller av skalelement kombinerade med balkelement. För utmattningsutvärdering med den nominella spänningsmetoden, ger balkmodeller som tar hänsyn till den lokala ledflexibiliteten tillräckligt realistiska resultat.
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Kesawan, Sivakumar. "Fire performance and design of light gauge steel frame wall systems made of hollow flange sections." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/120153/1/Kesawan_Sivakumar_Thesis.pdf.
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Load bearing Light Gauge Steel Frame (LSF) wall system is a cold-formed steel structure made of cold-formed steel studs and lined on both sides by gypsum plasterboards. In recent times its use and demand in the building industry has significantly increased due to their advantages such as light weight, acoustic performance, aesthetic quality of finished wall, ease of fabrication and rapid constructability. Fire Resistant Rating (FRR) of these walls is given more attention due to the increasing number and severity of fire related accidents in residential buildings that have caused significant loss of lives and properties.
LSF walls are commonly made of conventional lipped channel section studs lined with fire resistant gypsum plasterboards on both sides. Recently, greater attention has been given to innovative cold-formed steel sections such as hollow flange sections due to their improved structural efficiency. The reliance on expensive and time consuming full scale fire tests, and the complexity involved in predicting the fire performance of LSF wall studs due to their thin-walled nature and their exposure to non-uniform temperature distributions in fire on one side, have been the main barriers in using different cold-formed steel stud sections in LSF wall systems. This research overcomes this and proposes the new hollow flange section studs as vertical load bearing elements in LSF wall systems based on a thorough investigation into their fire (structural and thermal) performance using full scale fire tests and extensive numerical studies.
Test wall frames made of hollow flange section studs were lined with fire resistant gypsum plasterboards on both sides, and were subjected to increasing temperatures as given by the standard fire curve in AS 1530.4 (SA, 2005) on one side. Both uninsulated and cavity insulated walls were tested with varying load ratios from 0.2 to 0.6. LiteSteel Beam (LSB), a welded hollow flange section, which was available in the industry was used to fabricate the test wall panels. Axial deformations and lateral displacements along with the time-temperature profiles of the steel stud and plasterboard surfaces were measured. Five full scale tests were performed, and the test results were compared with those of LSF walls made of lipped channel section studs, which proved the superior fire performance of LSF walls made of hollow flange section studs. The reasons for the superior fire performance are presented in this thesis. The effects of load ratio and plasterboard joint on the fire performance of LSF walls and temperature distribution across the stud cross-sections were identified.
Improved plasterboard joints were also proposed.
The elevated temperature mechanical properties of cold-formed steels appear to vary significantly as shown by past research. LSBs were manufactured using a combined cold-forming and electric resistance welding process. Elevated temperature mechanical properties of LSB plate elements are unknown. Therefore an experimental study was undertaken to determine the elevated temperature mechanical properties of LSB plate elements. Based on the test results and previous researchers' proposed values, suitable predictive equations were proposed for the elastic modulus and yield strength reduction factors and stress-strain models of LSB web and flange elements.
Uninsulated and insulated 2D finite element models of LSF walls were developed in SAFIR using GiD as a pre- and post processor to predict the thermal performance under fire conditions. A new set of apparent thermal conductivity values was proposed for gypsum plasterboards for this purpose. These models were then validated by comparing the time-temperature profiles of stud and plasterboard surfaces with corresponding experimental results. The developed models were then used to conduct an extensive parametric study. Uninsulated and insulated LSF walls with superior fire performances were also proposed.
Finite element models of tested walls were also developed and analysed under both transient and steady state conditions to predict the structural performance under fire conditions using ABAQUS. In these analyses, the measured elevated temperature properties of LSB plate elements were used to improve their accuracy. Finite element analysis results were compared with fire test results to validate the developed models. Following this, a detailed finite element analysis based study was conducted to investigate the effects of stud dimensions such as web depths and thicknesses, elevated temperature mechanical properties, types of wall configurations, stud section profiles, plasterboards to stud connections and realistic design fire curves on the fire performance of LSF walls. It was also shown that the commonly used critical temperature method is not appropriate in determining the FRR of LSF walls.
Gunalan and Mahendran's (2013) design rules based on AS/NZS 4600 (SA, 2005), and Eurocode 3 Part 1.3 (ECS, 2006) were further improved to predict the structural capacity of hollow flange section studs subjected to non-uniform temperature distributions caused by fire on one side. Two improved methods were proposed and they predicted the FRRs with a reasonable accuracy. Direct Strength Method (DSM) based design rules were then established and they also predicted the FRR of LSF walls made of hollow flange section studs accurately. Finally, spread sheet based design tools were developed based on the proposed design rules.
Overall, this research has developed comprehensive fire performance data of LSF walls made of hollow flange section studs, accurate design rules to predict their fire rating and associated design tools. Thus it has enabled the use of innovative hollow flange sections as studs in LSF wall systems. Structural and fire engineers can now use these tools to undertake complex calculations of determining the structural capacities and fire rating of hollow flange section studs subjected to non-uniform temperature distributions, and successfully design them for safe and efficient use in LSF walls of residential and office buildings.
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Perera, Nilakshi. "Structural behaviour and design of innovative hollow flange steel plate grinders." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/123310/1/Liyanage%20Nilakshi%20Piyahasi_Perera_Thesis.pdf.
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This thesis proposes a new Hollow Flange Steel Plate Girder (HFSPG) by welding industrially available cold-formed Rectangular Hollow Sections (RHS) to a web plate for use in long span construction. Design procedures presented in the national and international design guidelines were reviewed and suitable improvements were made to accurately predict the structural behaviour and capacities of HFSPGs by undertaking detailed experimental and numerical studies into their unique structural behaviour. Local buckling/yielding, global buckling and local-global interaction failures were all considered in this thesis.
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Pitrakkos, Theodoros. "The tensile stiffness of a novel anchored blind-bolt component for moment-resisting connections to concrete-filled hollow sections." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/13937/.
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The use of hollow section columns in steel construction is presently hindered by the lack of adequate connection technologies. Due to access constraints, standard bolting techniques are difficult to achieve, if not impossible without welding. As an alternative to welding, blind-bolting techniques were developed to provide desirable bolted configurations, allowing hollow column frames to be erected in the same way as open profile column frames. But the current blind-bolting techniques are restricted to the construction of simple connections because of their difficulties in achieving sufficient tensile stiffness. More recently, a novel anchored blind-bolt, labelled the Extended Hollo-bolt (EHB), has been developed at the University of Nottingham; as a modification of the standard Hollo-bolt. For the proposed connection technology, its potential in providing moment-resistance has been assessed successfully. However, the existing data related to the performance of this novel connector in tension is insufficient to permit its design. This work investigates the performance of the EHB blind-bolt under tension loading and focuses on determining, and modelling the stiffness of this novel technology in such a way to enable its application within the component method approach. An extensive experimental programme was devised to collect sufficient component characteristic data to enable the development of an EHB component model. This covered data deals with the overall response of the connector and the individual responses of its contributing elements. A total of 51 experimental pull-out tests and 20 pre-load tests have been performed. The force-displacement behaviour of the investigated joint component was determined under monotonic pull-out testing, where remote video gauge techniques have been adopted to capture the full non-linear response of the component, alongside traditional techniques to confirm the reliability of the data. The test matrix varies the grade and size of the component's internal bolt, the strength of concrete, and the depth of its mechanical anchorage. From the pull-out tests it was identified that the EHB component can ultimately develop the full tensile capacity of its internal bolt. This ultimate failure mode is confirmed for the range of parameters that was covered in this study. Increasing concrete strength had the most enhancing effect on the response of the component. A secondary programme was related to the measurement of pre-load that is induced in the internal bolt of the EHB component at its tightening stage; where pre-load was monitored over a five day period. The test matrix varies the grade and size of its internal bolt, and also considers various bolt batches. It was concluded that the relative level of component pre-load to ultimate strength increased only in the case where higher bolt grades were used. To model the tension behaviour of the EHB component, a mechanical model was developed that is based on an assembly of the component's different sources of deformation. The component model employs idealised springs with tetra-linear characteristics for the elongation of Its Internal bolt element, and springs with tri-linear characteristics for the slip of its expanding sleeves and mechanical anchorage elements. By comparing the predictions of the component model with relevant experimental data, the component model has been shown to be capable of describing the EHB component response with reasonable accuracy; capturing its tensile stiffness and its yielding trend. The accuracy of the component model has also been assessed in exclusion of pre-load effects. It was found that if the level of pre-load Is excluded from the assembly process, this can have highly undesirable effects on the predictions of the component's response. The findings of the supplementary pre-load testing programme assisted greatly in the accuracy of the component model by providing the necessary levels of pre-load. The proposed component model has demonstrated that the behaviour of the EHB component can be modelled by the component method approach; by employing Idealised models for the behaviour of its contributing elements. The validated component model is considered to simulate the tension behaviour of the novel anchored blind-bolt with sufficient fidelity that it can be considered as a benchmark for further studies.
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Alzghoul, Ahmad, and Burim Hyseni. "Övergång till högre stålhållfastheter - konsekvensanalys." Thesis, Högskolan i Halmstad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35844.
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Tao, Yunxiang. "Advanced numerical analysis and fire testing of cold-formed steel hollow section stud walls." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/226716/1/Yunxiang_Tao_Thesis.pdf.
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This research investigated the behaviour of light gauge steel frame walls made of cold-formed steel hollow section studs under both ambient and fire conditions using full scale experimental and advanced numerical studies. It developed and improved new structural and fire design rules for hollow section stud walls that can be included in the Australian steel structures standard. Importantly, it showed that such wall systems have superior fire resistance than conventional wall systems used currently. Overall, this research has sufficiently improved the knowledge of light steel walls made of hollow section studs in fire, enabling structurally efficient and safer designs.
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Kim, Jimmy. "Development of modular building systems made of innovative steel sections and wall configurations." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/127327/1/Jimmy_Kim_Thesis.pdf.
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This study has presented a thorough review on steel Modular Building Systems including the execution of case studies on real-world MBS projects to establish an understanding of the current development and shortcomings of this emerging technology for which innovative solutions are later introduced. The review determined that the major limitations of this technology included lack of structurally-efficient designs, poor control of construction tolerances, impractical to construct designs and lack of measures to address fire-resisting performance. Several innovative design concepts were incorporated into a complete MBS module and proposed to address these shortcomings.
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Andersson, Sebastian. "Varmformade eller kallformade konstruktionsrör ur ett lönsamhetsperspektiv : Undersökning av ekonomisk differens i valet mellan VKR och KKR." Thesis, Mittuniversitetet, Avdelningen för ekoteknik och hållbart byggande, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-25151.
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I Sverige kan VKR (varmformade konstruktionsrör) vara 15-23 % dyrare än KKR (kallformade konstruktionsrör) av samma tvärsnittsstorlek. Trots detta lägre pris på KKR har det uppskattats att i Svensk stålbyggnation används endast 5 % KKR, av det totala användandet av VKR och KKR. I detta examensarbete har det först undersökts vilka skillnader i egenskaper som finns mellan VKR och KKR. Därefter beräknas prisdifferensen mellan de två profiltyperna när de utsätts för en centrisk tryckkraft under likadana förhållanden. Målet är att ta reda på vilket som är det mest ekonomiskt lönsamma alternativet i valet mellan VKR och KKR. Tryckkraftskapaciteten med hänsyn till knäckning för alla profilstorlekar i Tibnor konstruktionstabeller har beräknats för varje möjlig kombination av tio olika längder mellan 1 till 10 m, tio olika laster mellan 100 till 1000 kN och två olika upplagsförhållanden, ledad i båda ändarna eller fast inspänd i båda ändarna. De KKR‑ respektive VKR-profiler med lägst pris, som håller för lasten, har jämförts och prisdifferensen mellan dessa redovisas genom att ange hur många procent dyrare, eller billigare, VKR är i jämförelse med KKR. I 80 % av mätningarna vid ledad infästning i båda ändarna blev KKR det mest ekonomiskt lönsamma alternativet. Samma siffra blev 86 % för fast inspänd i båda ändarna. Den genomsnittliga prisdifferensen hamnade på 10-11 % med ett spridningsmått på 8-12 %. Detta leder till slutsatsen att ett användande av enbart KKR kan resultera i besparingar på ca 10‑11 % i stålkostnader, jämfört med att enbart använda VKR. Utifrån prisdifferensernas variation dras därefter slutsatsen att det inte finns några tendenser på att VKR eller KKR är mer lönsam än den andra inom något specifikt längd- eller lastintervall. Rekommendationen är att i första hand optimera och använda den profiltyp som är mest lönsam för rådande förhållanden. Om en optimering inte är möjlig blir istället rekommendationen att använda KKR.In Sweden, hot formed rectangular hollow sections (HFRHS) can be 15-23 % more expensive than cold formed rectangular hollow sections (CFRHS) of the same section size. Although the price on CFRHS is lower, estimations reveals that - from the total use of HFRHS and CFRHS in Swedish steel buildings - CFRHS is only utilized by less than 5 % compared to 95 % HFRHS. This study began by examining the differences between these two types of steel. The price difference between the two processed metal types was then calculated when both of them were subjected to a centric compressive force under the same conditions. The purpose was to compare prices and find out which one is the most economically feasible, offering a more profitable choice between HFRHS or CFRHS. The design buckling resistance of all the section sizes in Tibnor konstruktionstabeller was calculated for every possible combination out of ten different lengths between 1 m and 10 m, ten different loadings between 100 kN and 1000 kN and two different support conditions being pinned at both ends and fixed at both ends. The sections sizes of CFRHS and HFRHS that withstood the loading and held the lowest prices were compared by calculating the price difference as percentage increment or decrement between the two types of hollow sections. In 80 % of the cases, when pinned at both ends, CFRHS showed to be the most economically feasible alternative. When fixed at both ends the same number was 86 %. The average price difference was 10-11 %, showing an absolute deviation of approximately 8‑12 %. These findings conclude that using only CFRHS can result in savings of 10‑11 % from reduced costs of steel, compared to only using HFRHS. From the observed variation of the price differences another conclusion is drawn that there aren’t any tendencies showing HFRHS or CFRHS to be more economically feasible than the other in a specific interval of length or loading. The recommendation is to optimize and use the type of steel that is the most economically feasible under the current circumstances. If an optimization isn’t possible then the recommendation is to use CFRHS.
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Abraham, Jeevan George. "A deflection, buckling and stress investigation into telescopic cantilever beams." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/7380.
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The telescoping cantilever beam structure is applied in many different engineering sectors to achieve weight/space optimisation for structural integrity. There has been limited theory and analysis in the public domain of the stresses and deflections involved when applying a load to such a structure. This thesis proposes (a) The Tip Reaction Model, which adapts classical mechanics to predict deflection of a two and a three section steel telescoping cantilever beam; (b) An equation to determine the Critical buckling loads for a given configuration of the two section steel telescoping cantilever beam assembly derived from first principles, in particular the energy methods; and finally (c) the derivation of a design optimization methodology, to tackle localised buckling induced by shear, torsion and a combination of both, in the individual, constituent, hollow rectangular beam sections of the telescopic assembly. Bending stress and shear stress is numerically calculated for the same structure whilst subjected to inline and offset loading. An FEA model of the structure is solved to verify the previous deflection, stress and buckling predictions made numerically. Finally an experimental setup is conducted where deflections and stresses are measured whilst a two section assembly is subjected to various loading and boundary conditions. The results between the predicted theory, FEA and experimental setup are compared and discussed. The overall conclusion is that there is good correlation between the three sets of data.
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Souza, Mauricio Guilherme Quilez. "Automação e integração CAD/CAE no projeto de estruturas metalicas, utilizando perfis tubulares." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257809.
Full textAbstract:
Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-09T16:24:16Z (GMT). No. of bitstreams: 1 Souza_MauricioGuilhermeQuilez_M.pdf: 5444391 bytes, checksum: f64376df9364d46cfcb18e6ba06eff3a (MD5) Previous issue date: 2006
Resumo: Este trabalho tem como objetivo o desenvolvimento de códigos de computador que têm a finalidade de automatizar as etapas principais de um projeto de estruturas metálicas através das linguagens AutoLISP e Delphi5. Os projetos de estruturas metálicas em estudo são os de coberturas com treliças planas constituídas de barras com perfis tubulares laminados sem costuras e seus contraventamentos. Estes perfis tubulares, ainda pouco utilizados em estruturas planas no Brasil, vêm sendo disseminados através do uso de programas que ajudam os engenheiros a utilizá-los adequadamente em seus projetos tendo em vista que resultam em estruturas mais leves e de fácil fabricação. Desta forma, houve a necessidade de desenvolver um sistema CAD/CAE, para automatizar a geração das geometrias das estruturas planas, além das representações gráficas do sistema geral tridimensional de contraventamentos da estrutura - CAD; exportar os dados para um programa integrado que realiza um processo otimizado de toda a análise estrutural e dimensionamento - CAE e, finalmente, retornar os dados processados para o ambiente CAD, para realizar o detalhamento automático das ligações da estrutura treliçada analisada. Todos os procedimentos adotados para automação dos projetos seguem recomendações de normas técnicas brasileiras principalmente a NBR8800/1986
Abstract: This work has as objective to show a software that have the goal to automate the main stages of a steel structural design, using AutoLISP and Delphi5 languages. The steel structural designs in case are the roofs formed by plane trusses made by hollow sections frames. These hollow steel sections, which are not highly used in plane structures in Brazil, are being disseminated by the use of softwares that help civil engineers to use them correctly in their designs, in view of that they result in less weighted and easy manufactured structures. So, there is the necessity to develop a CAD/CAE system, that will automate the generation of the geometries from plane structures and the graphical designs from the three-dimentional general system - CAD; also, we have the necessity to export the data to an integrated computer program that executes an optimized process from the entire structural analysis and design - CAE; and, finaly, to return the proceeded data back to CAD environment, to draw the automatic details from the connections of the analyzed structure. All the procedures and methods used to automate the design follows the specifications of Brazilian Design Codes, mainly the NBR-8800/1986
Mestrado
Estruturas
Mestre em Engenharia Civil
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Sepúlveda, Bárbara Daniela Giorgini 1986. "Influência das ligações no dimensionamento das estruturas tubulares circulares de aço treliçadas." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258631.
Full textAbstract:
Orientador: João Alberto Venegas RequenaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Este artigo apresenta o estudo da influência das ligações no comportamento das estruturas treliçadas compostas por perfis tubulares de aço. As ligações em treliças de aço são normalmente projetadas para união de barras por meio de chapas que garantam a transmissão e equilíbrio das forças. No caso em particular de treliças que utilizam perfis tubulares de aço as ligações são projetadas sem chapas. As barras são unidas diretamente por meio de soldas nos contatos dos perfis que são cortados geometricamente exatos para o ajuste da ligação. Este procedimento aumenta a produtividade de fabricação além de dar um aspecto visual melhor para a estrutura. Dependendo da geometria da ligação podem ocorrer excentricidades dos eixos provocando a introdução de momentos fletores, que quando não puderem ser evitados, devem ser levados em consideração não só no cálculo da ligação como também na determinação dos esforços da treliça. Outro aspecto importante é a análise do colapso da ligação que pode ocorrer quando uma barra é associada à outra de forma inadequada na ligação direta, sendo variados os tipos de falhas. Portanto, será analisada a influência das ligações no comportamento da estrutura a partir de gráficos baseado no estudo das equações de força resistente das ligações tubulares circulares. Este estudo gráfico permitiu a criação do processo de cálculo, denominado Processo Simplificado, que orientam para as combinações de perfis que atendam as exigências geométricas e de força resistente das ligações durante o dimensionamento de barras. O processo é baseado em de tabelas de cálculo desenvolvidas para a orientação de um bom projeto de estrutura treliçada considerando ou evitando estas influências sem onerar o projeto final
Abstract: This paper presents the study of connections influence in the behavior of hollow sections truss structures. Joints in steel trusses are usually designed considering sheets that will ensure the transmission and balance of forces. In particular case of trusses using hollow sections steel connections are designed without plates. The beams are directly welded to steel sections which are geometrically cut to fit the joint. This increases manufacturing productivity in addition to give the structure a better visual appearance. Axes eccentricities can occur depending on connection geometry resulting in introduction of bending moments. When this eccentricity cannot be avoided, it has to be taken into account in joint design and also in determining truss efforts. Another important aspect is analysis joint collapse which can occur when a beam is improperly associated to another beam, which can produce many kinds of fails. Therefore, graphics analyses were studied based on circular hollow sections joint strength equations that show the influence of joints on structures. The Simplified Process, created after graphics studies, shows the valid combinations of circular hollow sections geometry and strength during beam structure design verification. This process is based on tables developed to orient a good truss project considering or avoiding this influences without raising budget on final design
Mestrado
Estruturas e Geotécnica
Mestra em Engenharia Civil
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Sheehan, Therese. "Cyclic behaviour of hollow and concrete-filled circular hollow section braces." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57941/.
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Presented in this thesis is an investigation on the response of hot-finished and cold formed, hollow and concrete-filled circular hollow section braces in earthquakeresisting concentrically braced frames. The role of these braces is to act as structural ‘fuses’ in the frame, dissipating the seismic energy by undergoing plastic deformations. Circular hollow sections offer aesthetic and structural advantages over conventional rectangular hollow sections owing to the uniformity of the section geometry. Distinct behaviour is observed between cold formed and hot-finished tubes, since the cold formed sections retain a higher degree of residual stresses from manufacturing. Braces subjected to cyclic loading fail after the occurrences of global and local buckling, but the performance can be enhanced by employing concrete infill. The concrete-filled steel tube is an optimum combination of the two materials, resulting in an efficient, economic and practical structural member. Experiments were performed in which cyclic axial loading was applied to hollow and composite braces of each section type. Hot-finished specimens exhibited superior ductility to cold formed members. Concrete infill enhanced the tensile resistance for members of all lengths, the compressive resistance of shorter members and the number of cycles to failure. Finite element models were subsequently developed with ABAQUS® software, using the inbuilt nonlinear isotropic/kinematic hardening model and the damaged plasticity model to define the steel and concrete characteristics. Reliable simulations were achieved for the hollow braces but further work is required for the composite braces. Both local and global slenderness values influenced the specimen response. Expressions were proposed to predict the displacement ductility and energy dissipation capability of hollow braces in terms of these parameters. The findings suggest that distinct guidelines could be developed for introduction into Eurocode 8 for each steel section type, and that the benefits of concrete infill could be taken into account in dissipative design.
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Messaoud, Saidani Ingenieur d' etat. "Joint flexibility in rectangular hollow section trusses." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398886.
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Kosteski, Nikola. "Branch plate-to-rectangular hollow structural section connections." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ63606.pdf.
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Law, Kwan Ho. "Instabilities in structural steel elliptical hollow section members." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6205.
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Elliptical hollow sections (EHS) have been recently added to the family of hollow steel sections available to the construction industry. Their merits include different flexural rigidities about the two principal axes offering efficient bending resistance about the major axis and an aesthetically pleasant appearance. A number of recent practical applications have emerged, which are outlined in this thesis. Previous research on elliptical hollow sections has mainly focused on the cross-section level with a set of design rules for cross-section classification and shear resistance being proposed. The current study reviews the existing cross-section classification limits for both circular and elliptical tubular sections and investigates member instability of EHS in bending (lateral torsional buckling) and under combined axial compression and bending. Reliability analyses to establish a set of reliable design rules for elliptical hollow sections in the Eurocodes and other international structural design codes have been also performed. The key components of this research include laboratory testing, numerical modelling, and development of statistically verified design guidance. A series of experimental studies were undertaken to investigate the buckling response of elliptical hollow section members in bending and under combined axial load and bending. In total, 8 beams, 6 columns and 27 beam-columns were tested; the test results were then used to calibrate finite element models. Parametric studies were performed utilizing the validated numerical models. Based on the experimental and numerical findings, reliability analyses were undertaken to verify design rules for elliptical hollow sections. It is envisaged that these design rules will be incorporated into future revisions of Eurocode 3.
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Espinós, Capilla Ana. "Numerical analysis of the fire resistance of circular and elliptical slender concrete filled tubular columns." Doctoral thesis, Editorial Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/17579.
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El empleo de pilares tubulares de acero rellenos de honnigón (CFT) ha crecido en las
últimas décadas, debido a su excelente comportamiento estructural, que aprovecha el efecto
combinado del acero y honnigón trabajando juntos. Esta asociación ofrece una serie de
ventajas que hacen de las columnas CFT una solución interesante: su alta capacidad portante
o su eficiente tecnología constructiva pueden citarse entre sus beneficios ampliamente
conocidos, que se completan con una elevada resistencia al fuego sin necesidad de protección
externa.
Tradicionalmente, se han venido utilizando secciones huecas circulares, cuadradas y
rectangulares para formar estas columnas compuestas. Adicionalmente, la sección elíptica ha
sido recientemente introducida dentro de la gama de secciones de acero huecas disponib les
comercialmente. Su atractivo estético y su reducida intrusión visual, junto con sus ventajas
estructurales asociadas a secciones con diferentes propiedades en sus ejes fuerte y débil,
hacen a las secciones elípticas de gran interés para los diseñadores. En esta tesis se estudian
pi lares CFT de sección tanto circular como elíptica.
Pese a que el comportamiento de los pilares CFT a temperatura ambiente ha quedado
bien establecido en los últimos años, en situación de incendio la degradación de las
propiedades del material da lugar a un comportamiento extremadamente no lineal de estas
columnas compuestas, lo que hace dificil predecir su fallo. El estado del arte en el campo del
comportamiento frente al fuego de columnas CFT se revisa en esta tesis, mostrando que es
necesario profundizar en su investigación para una comprensión completa del funcionamiento
de tales columnas en situación de incendio. En el caso de las secciones elípticas, este trabajo
constituye una investigación novedosa.
El comportamiento frente al fuego de los pilares CFT se estudia en esta tesis por
medio de un modelo realista tridimensional de elementos finitos. Los valores adoptados de los
parámetros delEspinós Capilla, A. (2012). Numerical analysis of the fire resistance of circular and elliptical slender concrete filled tubular columns [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/17579
Palancia
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Philiastides, Antony. "Fully overlapped rolled hollow section welded joints in trusses." Thesis, University of Nottingham, 1988. http://eprints.nottingham.ac.uk/12416/.
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The designer of lattice trusses has been traditionally encouraged to avoid extra joint bending moments by ensuring 'noding' of member centre lines. This can however cause problems in the design of RHS trusses with small (economical) branch members by causing large gaps at joints with undesirable flexibility for slender chord walls. 100% overlap joints overcome this problem while still maintaining economic single cut branch ends. The research programme set out first to highlight the difference in behaviour of trusses with large gap noding and completely overlapping joints. Two similar trusses - one gap, the other lap - with matched sections were tested to failure. It was concluded that the gap joint truss (branch/chord width ratio = 0.4) was much less efficient than the corresponding 100% overlap truss despite the large eccentricities. The collapse load of the latter was some 35% greater, while the stiffness properties were better, and remained linear for a substantial proportion of the loading. On the other hand the gap joint truss soon became non-linear, with large overall deflections. Local connecting chord wall deflections were quite small in the lap joints while appreciable deflections occurred at gap joints under service loads. Elastic frame analyses were carried out for all the six test trusses (one gap and five lap). For the overlap trusses, axial forces and bending moments could be predicted fairly accurately but a non-linear analysis was required for the gap jointed truss even at fairly modest loads. The effects of ß ratio, chord slenderness and branch angle were all examined within the parameter range tested. The advantages of truss continuity moments as well as plastic redistribution of moments have been observed to reduce the occurrence of the local chord buckling mode of failure (L7), compared with previous isolated joint tests. Results obtained from tests on isolated joints can give good agreement with those obtained from truss tests, both with respect to strength and failure mode. However, as the isolated joint testing cannot always reproduce the support conditions in a truss, the failure modes (and hence strengths) can differ. The current CIDECT design strength equations and recommendations for gap and overlap joints are largely based on the results of isolated joint testing. The suitability of the CIDECT strength equations and recommendations for designing RHS lattice trusses has been reviewed. Consequently, for the 100% overlap joint trusses a simple design method has been presented in conjunction with practical design recommendations. The problems associated with the analysis and design of the gap joint truss are described in detail.
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Frazier, Alicia. "Accuracy and precision of a sectioned hollow model." Oklahoma City : [s.n.], 2008.
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Schumacher, Ann. "Fatigue behaviour of welded circular hollow section joints in bridges /." Lausanne : EPFL, 2003. http://library.epfl.ch/theses/?nr=2727.
Full textAbstract:
Thèse sc. techniques Lausanne EPFL, 2003 ; no 2727.Thèse no 2727(2003) présentée à la Faculté Environnement naturel, architectural et construit, Section de génie civil, Ecole Polytechnique Fédérale de Lausanne, pour l'obtention du grade de Docteur ès sciences techniques. Literaturverz.
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Kelly, Robert. "The influence of member orientation on hollow section joint strength." Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/13287/.
Full textAbstract:
The influence of the member orientation on the strength of joints formed with square hollow sections is examined. The bird beak joint system is a relatively new truss arrangement for square hollow sections, where the chord and the brace have each been rotated by 45° about their own centreline axes. Based on previous experimental testing it has been suggested that this joint system leads to a stronger joint arrangement. Finite element analysis has been used to study the strength and behaviour of such bird beak joints and to compare them to similar joints in CHS and the traditional RHS configuration to test this claim. A comprehensive study has been undertaken for bird beak X -joints and T -joints and comparisons are made with similar traditional joints in RHS and CHS as the parameters of the width ratio ß, the chord slenderness ratio 2y and the chord length ratio a are varied. Displaced shape and contoured stress plots are included to aid understanding of the failure mechanisms. The finite element work on K -joints allows comparisons of the strength and stiffness of bird beak K -joints with those formed in the traditional RHS configuration as the boundary conditions (at the ends of the members), the brace angle and loading conditions are varied. A limited amount of experimental work has been carried out in the laboratories at Nottingham University, with some assistance from the author, involving the physical testing of bird beak joints so that the finite element models can be validated. This work is reported and examined critically. The conclusions focus on the claims that the bird beak joints are stronger and how they differ from the traditional form of joints. Equations are presented to extend the design information available for a practical parameter range.
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Misiūnaitė, Ieva. "Santvarų nelakštinių mazgų skaičiavimo ir konstravimo ypatumai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080625_075537-12233.
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Baigiamajame magistro darbe nagrinėjami santvarinių konstrukcijų iš kvadratinių vamzdžių tiesioginio jungimo mazgų skaičiavimo ir konstravimo ypatumai. Analizuojama konstrukcinių elementų elgsena mazge ir jos sąlygojamas jungties irties pobūdis. Nagrinėjamos takumo linijos teorijos taikymo galimybės sudarant analitinius modelius. Pateikiami analitiniai modeliai, taikomi mazgų ašinės laikomosios galios skaičiavimo algoritmams sudaryti, pateikiamiems projektavimo norminiuose dokumentuose. Aprašomas mazgą sudarančių konstrukcinių elementų projektavimas pagal STR 2.05.08:2005 ir EN 1993-1-1 reikalavimus, bei mazgų ašinės laikomosios galios nustatymas pagal STR 2.05.08:2005 8-tą priedą, bei EN 1993-1-8.
Darbe atlikta skaitinė projektavimo normose pateikiamų santvarinių konstrukcijų tiesioginio jungimo mazgų ašinės laikomosios galios nustatymo lyginamoji analizė. Suprojektuota santvarinė konstrukcija, kurios skaičiuojamoji schema parinkta tokia, kad būtų išanalizuoti visi projektavimo normose pateikiami tiesioginio jungimo mazgų tipai. Įrąžoms konstrukciniuose elementuose nustatyti pasinaudota kompiuterine skaičiavimo programa Staad.pro. Konstrukcinių elementų elgsenos mazge analizei pasinaudota kompiuterine programa CosmosWorks. Ištirta pagrindinių skaičiavimo algoritmuose pateikiamų rodiklių įtaka mazgo laikomąjai galiai. Norint parinkti santvaros konstrukcinius elementus ir nustatyti mazgų skaičiuotinę ašinę laikomąją galią bei atlikti skaitinę analizę buvo pasinaudota... [toliau žr. visą tekstą]This master thesis considers design and estimation of truss joints between square hollow sections. Behaviuor of joints and its failure modes analyzed. The posibility to apply the yield line theory for analytical models considered. Analytical models used for determining the design capacity of the joint formulae in design guids presented. Truss members design following STR 2.05.08:2005 and EN 1993-1-1 and joint design capacity calculation following STR 2.05.08:2008 8-th annex and EN 1993-1-8 presented. It was made numerical convergence analysis between diferent design guidilines for estimating design capacity of the joint in this study. Truss structure designed, including all most commonly known joint types. Truss member loiding estimated using structural design and analysis software Staad.Pro. The behaviuor of the joint designed using finite element analysis software Cosmos.Works. Also the influence of governing joint parameters for the design capacity equations analysed. For truss structure design, capacity of the joint calculations and numerical analysis the calculation program was made using Microsoft Office Exel software.
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Khador, Majd. "Cyclic behaviour of external diaphragm joint between steel I-section beam and circular hollow section column." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/66903/.
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Tubular columns own many structural and architectural advantages that, in certain cases, make them more favourable than open-section columns in steel moment-resisting frames. These advantages are sometimes underexploited due to the relative lack of design guidance on their moment joints to open-section beams, in particular on semi-rigid joints with special detailing for seismic actions. Different configurations of I-beam to tubular column joints have been investigated in the past, including through, internal and external diaphragm joints. This project investigates experimentally the cyclic behaviour of an external diaphragm joint between a steel I-beam and a circular hollow section column. The proposed joint includes two diaphragm plates (DPs) welded to the outer circumference of the column and bolted to the I-beam flanges with two tapered cover plates (TCPs). A web stub is welded to the column face and bolted to the I-beam web. Full-scale laboratory experiments were conducted to investigate the hysteretic response and energy dissipative performance of the proposed joint under cyclic loading. TCPs were integrated in the joint to act as replaceable sacrificial components that dissipate most of the energy whilst the rest of the joint components remain elastic to minimise the post-seismic repair. The test specimens were identical except their TCPs that had the same geometry but differed in steel grade, size of bolt-holes, use of stiffeners or bolt preloading force. The use of higher grades of steel for the TCPs and stiffening them imposed higher strain demands in the beam and DPs and dissipated less energy than the joints with lower grades and unstiffened TCPs, respectively. The results confirmed that the main energy dissipation fuse in these joints was yielding in the TCPs while the other components remained elastic. Connection slippage created a second fuse for energy dissipation when the bolt preloading force was properly controlled, and the rotation of the plastic hinge region exceeded the minimum threshold of 25mrad for medium ductility class structures.
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Scullion, Tom. "Performance of elliptical steel hollow section columns, subjected to hydrocarbon fire." Thesis, University of Ulster, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.593881.
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The elliptical hollow section (EHS) is the most recent addition to the steel hollow section (SHS) family, providing an alternative hollow section solution, for architects and structural design engineers. However, despite the extensive interest in their use on the basis of both architectural attraction and structural efficiency, a complete absence of fire resistance data and design guidance is restraining applications. This experimental and numerical analysis investigation has studied, for the first time, the structural performance of steel columns with elliptical hollow section, when subjected to extreme temperatures, represented by the hydrocarbon fire curve. A total of 12 unfilled, unprotected pin-ended elliptical hollow section steel columns were tested in a two part experimental programme. Two different sections were tested, 250 x 125 x 8.0 mm and 200 x 100 x 8.0 mm with slenderness Az = 40.1 and Az = 50.8, namely EHS-A and EHS-B respectively. The first stage tested six columns, three of each slenderness, unrestrained and under three different loading levels (al. = 0.3, 0.45, 0.6). These f irst tests demonstrated the unique local and overall buckling failure modes of the EHS co lumns under compressive loads and elevated temperatures, while recording invaluable load-displacement data, paralleled with steel temperature profiles. The second stage of the experimental program applied axial restraint against the EHS columns thermal expansion. As columns are rarely used in isolation, the application of an axial restraint represents a more rea listic column boundary condition found in construction. This study il lustrates that the additional axial forces present when restraint is applied, will accelerate the failure rates of the EHS columns. The recorded experimental data and the fin ite element method (FEM) was utilised to quantitatively express the performance of the EHS columns. The calibrated model demonstrated that a very good numerical approximation solution was obtained, on careful consideration to the thermal expansion coefficient and geometric imperfection of the column. Using the FEM model, a comprehensive parametric analysis was performed, which provided a platform to aid in the development of the critical buckling stress equation and validation of design guidance. A proposed theoretical formula for stub columns in compression under elevated temperatures is also presented. The thesis concludes that the current Eurocode method for determining the critical temperature of steel hollow sections is deemed safe for unprotected elliptical hollow section steel columns under uniform compression.
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Abd, Rahman Norashidah. "Fatigue behaviour and reliability of Extended Hollobolt to concrete filled hollow section." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12909/.
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The need to provide mechanical connection from one side for the Hollow section connection has arisen in a number of fields and has resulted in the development of several types of so-called blind fasteners. An experimental blind bolt called the Extended Hollobolt is giving a good behaviour performance in terms of stiffness, strength and ductility. The strength performance of this system has been investigated under both monotonic and cyclic loading. However, the performance of such connections under fatigue loading is still unknown. The aim of this study was to investigate the behaviour of blind bolt connection to concrete filled hollow section under repeated load. Further aim was to determine the reliability of the Extended Hollobolt to concrete filled hollow section. The study involved conducting an experimental programme and carrying out fatigue life and reliability analysis. The experiment programme tested 52 specimens of bolts connected to concrete filled hollow sections where 36 tests involved Extended Hollobolt, 10 standard Hollobolt and 6 standard bolts (M16). The test specimens were subjected to tensile fatigue load characteristics with varying stress ranges. Mathematical methods are used to analyse the fatigue test data using the normal, lognormal and Weibull distributions. Normal and lognormal distributions are more suitable. Therefore, statistical analysis procedure proposed by Eurocode for the statistical analysis is valid for fatigue test data. Statistical analysis was conducted to establish S-N curves and to predict the fatigue life of the proposed blind bolt. This was then compared to the normative regulation in Eurocode 3. The failure mode of the Extended Hollobolt under repeated loading was found to be similar with standard bolt, which is a very positive outcome. Statistical analysis of fatigue test data showed that the fatigue life of Extended Hollobolt is higher than the theoretical design S-N curve which is recommended by Eurocode 3 part 1-9 for the standard bolt. However, the actual fatigue life for the standard bolt appears to be higher than the proposed blind bolt. A design model for predicting the fatigue life using S-N curve for the Extended Hollobolt is proposed. A reliability analysis using FORM (First Order Reliability Method) analysis shows that Extended Hollobolt is reliable in connections to concrete filled hollow sections where the safety index is 4.2.
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Omair, Moayad R. "The behaviour of welded T-end plate connections to rectangular hollow section (RHS)." Thesis, Coventry University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313163.
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Dexter, E. M. "Effects of overlap on behaviour and strength of steel circular hollow section joints." Thesis, Swansea University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636443.
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In response to frequent calls during the last few years for research into overlapped joints in steel circular hollow sections, this thesis addresses the static strength and behaviour of axially loaded overlapped K joints. A review of previous research and design guidance indicates the dearth of reliable, representative data and a general lack of knowledge of the behaviour of these joints, which are widely recognised as being potentially more cost effective than typical canned or stiffened gap joints. Preliminary, non-linear, numerical analyses, including thorough calibration of the Finite Element modelling strategy, are followed by a substantial parametric study investigating the effects of variation of the principal geometrical parameters on the behaviour and capacity of both overlapped and, for comparison, small-gap K joints. The results are compared with the design guidance of CIDECT (1991), which, for the overlapped joints, fails to predict all the interactive effects of the geometry variations and, consequently, is excessively conservative for some geometries. A new strength equation for overlapped K joint capacity is therefore proposed, based on the results of the numerical study. The equation has limited use in practice at present because of the limited scope of the parametric study. Nevertheless, it provides a robust platform onto which the results of future selective research (the requirement of which are discussed) may be added. Some important findings within the field of strength of tubular joints also emerge, namely: a) the effects of different boundary conditions on isolated joint tests - for replicating frame effects and the consequences for database screening, b) the reliability of the on- and offshore codes for gap K joint capacity, and c) the effects of chord can length on gap K joint capacity.
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Ozyurt, Emre. "Behaviour of welded tubular structures in fire." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/behaviour-of-welded-tubular-structures-in-fire(15601ab3-8f6c-4e64-ba1a-6201e66e9e16).html.
Full textAbstract:
This thesis presents the results of a research project to develop methods to carry out fire safety design of welded steel tubular trusses at elevated temperatures due to fire exposure. It deals with three subjects: resistance of welded tubular joints at elevated temperatures, effects of large truss deflection in fire on member design and effects of localised heating. The objectives of the project are achieved through numerical finite element modelling at elevated temperatures using the commercial Finite Element software ABAQUS v6.10-1 (2011). Validation of the simulation model for joints is based on comparison against the test results of Nguyen et al. (2010) and Kurobane et al. (1986). Validation of the simulation model for trusses is through checking against the test results of Edwards (2004) and Liu et al. (2010).For welded tubular joints, extensive numerical simulations have been conducted on T-, Y-, X-, N- and non-overlapped K-joints subjected to brace axial compression or tension, considering a wide range of geometrical parameters. Uniform temperature distribution was assumed for both the chord and brace members. Results of the numerical simulations indicate for gap K- and N-joints (two brace members, one in tension and the other in compression) and for T-, Y- and X-joints with the brace member under axial tensile load (one brace member only, in tension), it is suitable to use the same ambient temperature calculation equation as in the CIDECT (2010) or EN 1993-1-8 (CEN, 2005a) design guides and simply replace the ambient temperature strength of steel with the elevated temperature value. However, for T-, Y- and X-joints under brace compression load (one brace member only, in compression), the effect of large chord deformation should be considered. Large chord deformation changes the chord geometry and invalidates the assumed yield line mechanism at ambient temperature. For approximation, the results of this research indicate that it is acceptable to modify the ambient temperature joint strength by a reduction factor for the elastic modulus of steel at elevated temperatures. In the current fire safety design method for steel truss, a member based approach is used. In this approach, the truss member forces are calculated at ambient temperature based on linear elastic analysis. These forces are then used to calculate the truss member limiting temperatures. An extensive parametric study has been carried out to investigate whether this method is appropriate. The parametric study encompasses different design parameters over a wide range of values, including truss type, joint type, truss span-to-depth ratio, critical member slenderness, applied load ratio, number of brace members, initial imperfection and thermal elongation. The results of this research show that due to a truss undergoing large displacements at elevated temperatures, some truss members (compression brace members near the truss centre) experience large increases in member forces. Therefore, using the ambient temperature member force, as in the current truss fire safety design method, may overestimate the truss member critical temperature by 100 °C. A method has been proposed to analytically calculate the increase in brace compressive force due to large truss deformation. In this method, the maximum truss displacement is assumed to be span/30. A comparison of the results calculated using the proposed method against the truss parametric study results has shown good agreement with the two sets of results, with the calculation results generally being slightly on the safe side. When different members of a truss are heated to different temperatures due to localised fire exposure, the brace members in compression experience increased compression due to restrained thermal expansion. To calculate the critical temperature of a brace member in a localised heated truss, it is necessary to consider this effect of restrained thermal expansion. It is also necessary to consider the beneficial effects of the adjacent members being heated, which tends to reduce the increase in compressive force in the critical member under consideration. Again, an extensive set of parametric studies have been conducted, for different load ratio, slenderness and axial restraint ratio. The results of this parametric study suggest that to calculate the critical temperature of a brace member, it is not necessary to consider the effects of the third or further adjacent members being heated. For the remainder of the heated members, this thesis has proposed a linear elastic, static analysis method at ambient temperature to calculate the additional compressive force (some negative, indicating tension) in the critical member caused by the heated members (including the critical member itself and the adjacent members). The additional compressive force is then used to calculate the limiting temperature of the critical member. For this purpose, the approximate analytical equation of Wang et al. (2010) has been demonstrated to be suitable.
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Kong, Hye-Eun. "Design of One-Story Hollow Structural Section (HSS) Columns Subjected to Large Seismic Drift." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/94024.
Full textAbstract:
During an earthquake, columns in a one-story building must support vertical gravity loads while undergoing large lateral drifts associated with deflections of the vertical seismic force resisting system and deflections of the flexible roof diaphragm. Analyzing the behavior of these gravity columns is complex since not only is there an interaction between compression and bending, but also the boundary conditions are not perfectly pinned or fixed. In this research, the behavior of steel columns that are square hollow structural sections (HSS) is investigated for stability using three design methods: elastic design, plastic hinge design, and pinned base design. First, for elastic design, the compression and flexural strength of the HSS columns are calculated according to the AISC specifications, and the story drift ratio that causes the interaction equation to be violated for varying axial force demands is examined. Then, a simplified design procedure is proposed; this procedure includes a modified interaction equation applicable to HSS column design based on a parameter, Pnh/Mn, and a set of design charts are provided. Second, a plastic hinge design is grounded in the concept that a stable plastic hinge makes the column continue to resist the gravity load while undergoing large drifts. Based on the available test data and the analytical results from finite element models, three limits on the width to thickness ratios are developed for steel square HSS columns. Lastly, for pinned base design, the detailing of a column base connection is schematically described. Using FE modeling, it is shown that it is possible to create rotational stiffness below a limit such that negligible moment develops at the column base. All the design methods are demonstrated with a design exampleMaster of Science
One-story buildings are one of the most economical types of structures built for industrial, commercial, or recreational use. During an earthquake, columns in a one-story building must support vertical gravity loads while undergoing large lateral displacements, referred to as story drift. Vertical loads cause compression forces, and lateral drifts produce bending moments. The interaction between these forces makes it more complex to analyze the behavior of these gravity columns. Moreover, since the column base is not perfectly fixed to the ground, there are many boundary conditions applicable to the column base depending on the fixity condition. For these reasons, the design for columns subjected to lateral drifts while supporting axial compressive forces has been a growing interest of researchers in the field. However, many researchers have focused more on wide-flange section (I-shape) steel columns rather than on tube section columns, known as hollow structural section (HSS) steel columns. In this research, the behavior of steel square tube section columns is investigated for stability using three design methods: elastic design, plastic hinge design, and pinned base design. First, for elastic design, the compression and flexural strength of the HSS columns are calculated according to current code equations, and the story drift that causes failure for varying axial force demands is examined. Then, a simplified design procedure is proposed including design charts. Second, a plastic hinge design is grounded in the concept that controlled yielding at the column base makes the column continue to resist the gravity load while undergoing large drifts. Based on the available test data and results from computational models, three limits on the width to thickness ratios of the tubes are developed. Lastly, for pinned base design, concepts for detailing a column base connection with negligible bending resistance is schematically described. Using a computational model, it is shown that the column base can be detailed to be sufficiently flexible to allow rotation. All the design methods are demonstrated with a design example.
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Balarupan, Manuvidhya. "Structural behaviour and design of cold-formed steel hollow section columns under simulated fire conditions." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/91533/1/Manuvidhya_Balarupan_Thesis.pdf.
Full textAbstract:
This thesis presented a comprehensive study on the fire performance of load-bearing high-strength and cold-formed steel hollow section columns using experimental and numerical investigations. Accurate design tools have been developed to predict the ambient and elevated temperature structural capacities and fire resistance ratings of these columns. These developed design methods can be used to decide where bare steel columns can be used, and to design any required fire protection. Overall this research has significantly improved the knowledge and understanding of the structural fire performance of cold-formed steel hollow section columns, and thus enabling considerable improvements to the fire safety of steel buildings.