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1
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.
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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.
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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.
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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.
3
Wilkinson, Timothy James. "The Plastic Behaviour of Cold-Formed Rectangular Hollow Sections." Thesis, The University of Sydney, 1999. http://hdl.handle.net/2123/843.
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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.
4
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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Mohan, Meera. "Connections in higher strength Grade C450 cold formed rectangular hollow sections." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24333.
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CIDECT guidelines for hollow steel joints were mainly based on research of ductile steel with yield strength up to 355 MPa. On higher strength, lower ductility steels (C450 and above) emerging, CIDECT in 2009, extended the design guidelines to C450 RHS connections also, with certain restrictions on material, geometry and class of RHS. An overall reduction factor of 0.9 in design strength and a cap on σy at 0.8 σu were also stipulated. Experimental studies were conducted at the University of Sydney to verify the need and justification for the CIDECT restrictions in C450 RHS connections. This thesis complements the experimental studies using numerical methods and some novel techniques including use of an adapted Lemaitre damage model to track fracture, tracking necking in coupon tests by using recorded engineering stress-strain data and filling in gaps in data by methods such as use of FEA and/or crosshead data, grouping variations in material test results suitably and adopting a weighted average method to depict true stress strain that would reflect plastic deformation and damage. The FE models with these features were initially benchmarked against coupon test results, then validated against RHS jointless tests and finally against 12 K gap joint tests. More than 80 parametric variations that might influence the strength and behaviour of these joints were analysed using FEA. The study led to proposals for modifications to chord plastification, punching shear, chord side wall design equations to better predict ultimate loads and fracture modes. Reduced ductility in the steel was dealt with through a modifier function that is not based on yield stress but instead recognises the reduced ultimate strains, damage parameter for fracture and the ultimate stress of the material. Another research achievement is the perfection of a methodology to numerically predict the fracture / failure behavior of RHS joints and to formulate or test, design criteria if required.
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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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Wheeler, A. T. "The behaviour of bolted moment end plate connections in rectangular hollow sections subjected to flexure." Phd thesis, Department of Civil Engineering, 1998. http://hdl.handle.net/2123/8669.
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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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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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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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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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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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Siahaan, Ropalin. "Structural behaviour and design of rivet fastened rectangular hollow flange channel beams." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/106913/1/Ropalin_Siahaan_Thesis.pdf.
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This thesis presents a study into the structural behaviour and design of the innovative rivet fastened Rectangular Hollow Flange Channel Beams (RHFCB). The RHFCB utilizes the inexpensive self-pierce rivet fastening in its fabrication, providing cost effective structural solutions in floor systems. The first part of the thesis focuses on the section moment capacities of the beams subject to local buckling effects while the second part investigates the member moment capacities of intermediate span beams subject to the unique lateral distortional buckling effects. Each part involves experimental investigations, advanced finite element analyses, parametric studies and design recommendations.
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Wanniarachchi, Somadasa. "Flexural behaviour and design of cold-formed steel beams with rectangular hollow flanges." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/29810/1/Somadasa_Wanniarachchi_Thesis.pdf.
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Until recently, the hot-rolled steel members have been recognized as the most popular and widely used steel group, but in recent times, the use of cold-formed high strength steel members has rapidly increased. However, the structural behavior of light gauge high strength cold-formed steel members characterized by various buckling modes is not yet fully understood. The current cold-formed steel sections such as C- and Z-sections are commonly used because of their simple forming procedures and easy connections, but they suffer from certain buckling modes. It is therefore important that these buckling modes are either delayed or eliminated to increase the ultimate capacity of these members. This research is therefore aimed at developing a new cold-formed steel beam with two torsionally rigid rectangular hollow flanges and a slender web formed using intermittent screw fastening to enhance the flexural capacity while maintaining a minimum fabrication cost. This thesis describes a detailed investigation into the structural behavior of this new Rectangular Hollow Flange Beam (RHFB), subjected to flexural action The first phase of this research included experimental investigations using thirty full scale lateral buckling tests and twenty two section moment capacity tests using specially designed test rigs to simulate the required loading and support conditions. A detailed description of the experimental methods, RHFB failure modes including local, lateral distortional and lateral torsional buckling modes, and moment capacity results is presented. A comparison of experimental results with the predictions from the current design rules and other design methods is also given. The second phase of this research involved a methodical and comprehensive investigation aimed at widening the scope of finite element analysis to investigate the buckling and ultimate failure behaviours of RHFBs subjected to flexural actions. Accurate finite element models simulating the physical conditions of both lateral buckling and section moment capacity tests were developed. Comparison of experimental and finite element analysis results showed that the buckling and ultimate failure behaviour of RHFBs can be simulated well using appropriate finite element models. Finite element models simulating ideal simply supported boundary conditions and a uniform moment loading were also developed in order to use in a detailed parametric study. The parametric study results were used to review the current design rules and to develop new design formulae for RHFBs subjected to local, lateral distortional and lateral torsional buckling effects. Finite element analysis results indicate that the discontinuity due to screw fastening has a noticeable influence only for members in the intermediate slenderness region. Investigations into different combinations of thicknesses in the flange and web indicate that increasing the flange thickness is more effective than web thickness in enhancing the flexural capacity of RHFBs. The current steel design standards, AS 4100 (1998) and AS/NZS 4600 (1996) are found sufficient to predict the section moment capacity of RHFBs. However, the results indicate that the AS/NZS 4600 is more accurate for slender sections whereas AS 4100 is more accurate for compact sections. The finite element analysis results further indicate that the current design rules given in AS/NZS 4600 is adequate in predicting the member moment capacity of RHFBs subject to lateral torsional buckling effects. However, they were inadequate in predicting the capacities of RHFBs subject to lateral distortional buckling effects. This thesis has therefore developed a new design formula to predict the lateral distortional buckling strength of RHFBs. Overall, this thesis has demonstrated that the innovative RHFB sections can perform well as economically and structurally efficient flexural members. Structural engineers and designers should make use of the new design rules and the validated existing design rules to design the most optimum RHFB sections depending on the type of applications. Intermittent screw fastening method has also been shown to be structurally adequate that also minimises the fabrication cost. Product manufacturers and builders should be able to make use of this in their applications.
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Wanniarachchi, Somadasa. "Flexural behaviour and design of cold-formed steel beams with rectangular hollow flanges." Queensland University of Technology, 2005. http://eprints.qut.edu.au/29810/.
Full textAbstract:
Until recently, the hot-rolled steel members have been recognized as the most popular and widely used steel group, but in recent times, the use of cold-formed high strength steel members has rapidly increased. However, the structural behavior of light gauge high strength cold-formed steel members characterized by various buckling modes is not yet fully understood. The current cold-formed steel sections such as C- and Z-sections are commonly used because of their simple forming procedures and easy connections, but they suffer from certain buckling modes. It is therefore important that these buckling modes are either delayed or eliminated to increase the ultimate capacity of these members. This research is therefore aimed at developing a new cold-formed steel beam with two torsionally rigid rectangular hollow flanges and a slender web formed using intermittent screw fastening to enhance the flexural capacity while maintaining a minimum fabrication cost. This thesis describes a detailed investigation into the structural behavior of this new Rectangular Hollow Flange Beam (RHFB), subjected to flexural action The first phase of this research included experimental investigations using thirty full scale lateral buckling tests and twenty two section moment capacity tests using specially designed test rigs to simulate the required loading and support conditions. A detailed description of the experimental methods, RHFB failure modes including local, lateral distortional and lateral torsional buckling modes, and moment capacity results is presented. A comparison of experimental results with the predictions from the current design rules and other design methods is also given. The second phase of this research involved a methodical and comprehensive investigation aimed at widening the scope of finite element analysis to investigate the buckling and ultimate failure behaviours of RHFBs subjected to flexural actions. Accurate finite element models simulating the physical conditions of both lateral buckling and section moment capacity tests were developed. Comparison of experimental and finite element analysis results showed that the buckling and ultimate failure behaviour of RHFBs can be simulated well using appropriate finite element models. Finite element models simulating ideal simply supported boundary conditions and a uniform moment loading were also developed in order to use in a detailed parametric study. The parametric study results were used to review the current design rules and to develop new design formulae for RHFBs subjected to local, lateral distortional and lateral torsional buckling effects. Finite element analysis results indicate that the discontinuity due to screw fastening has a noticeable influence only for members in the intermediate slenderness region. Investigations into different combinations of thicknesses in the flange and web indicate that increasing the flange thickness is more effective than web thickness in enhancing the flexural capacity of RHFBs. The current steel design standards, AS 4100 (1998) and AS/NZS 4600 (1996) are found sufficient to predict the section moment capacity of RHFBs. However, the results indicate that the AS/NZS 4600 is more accurate for slender sections whereas AS 4100 is more accurate for compact sections. The finite element analysis results further indicate that the current design rules given in AS/NZS 4600 is adequate in predicting the member moment capacity of RHFBs subject to lateral torsional buckling effects. However, they were inadequate in predicting the capacities of RHFBs subject to lateral distortional buckling effects. This thesis has therefore developed a new design formula to predict the lateral distortional buckling strength of RHFBs. Overall, this thesis has demonstrated that the innovative RHFB sections can perform well as economically and structurally efficient flexural members. Structural engineers and designers should make use of the new design rules and the validated existing design rules to design the most optimum RHFB sections depending on the type of applications. Intermittent screw fastening method has also been shown to be structurally adequate that also minimises the fabrication cost. Product manufacturers and builders should be able to make use of this in their applications.
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Johnson, Graham Roy. "Experimental and numerical investigation into impact bending collapse of rectangular hollow sections." 2001. http://hdl.handle.net/2100/1102.
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University of Technology, Sydney, 2001.This thesis describes a program of research into the plastic moment - rotation (M-8) response of rectangular hollow section (RHS) steel tubes subjected to impact bending loads. The context for this research was the use of RHS in buses and vehicle rollover protection structures (ROPS) where the "plastic hinges" that form in the RHS members act as energy absorbing "crumple zones". In the design of such structures for crash worthiness, there is a need to understand the response of the plastic hinges to impact loading and this research has assessed the following methods used to determine the moment - rotation characteristics of plastic hinges under impact bending loads: * physical impact tests; * finite element modelling; and * the use of "dynamic magnifiers" to scale the results of quasi-static tests and analyses. In dynamic tests, the specimen's inertia complicates the measurement of plastic hinge properties. These complications were addressed by the design and development of a novel pendulum bend rig and instrumentation and the meticulous processing of test data. The test rig and procedures were successfully used to measure the bending collapse of 50x50x2 grade C350LO RHS specimens to a hinge rotation of 35°. Comparisons between the measured impact and quasi-static responses enabled the influence of the loading rate on plastic hinge response to be quantified. It is shown that the difference between the impact and static responses is essentially due to the RHS material's strain rate sensitivity. This influence of strain rate on the mechanical properties of the RHS material was characterised by a programme of uni-axial tensile tests at strain rates ranging from 10 -4 to 10 s -1. Detailed finite element analyses of the local buckling response were conducted using HKS ABAQUS-Standard. Excellent agreement between the predicted and measured impact M-8 responses of the local buckle was obtained using a "pseudo-dynamic" analysis procedure. This procedure correctly accounted for the effect of material strain rate sensitivity within a static analysis by controlling the loading rate. A critical assessment was made of the quasi-static scaling approach to predicting component impact response. The limitations of predicting impact moment and energy responses using a single scaling factor were demonstrated. It is shown that the most reliable results are obtained using a scaling factor derived experimentally. A theoretical approach proposed in the literature to predict RHS plastic hinge impact response is shown to overestimate the impact response of the RHS tested in this study. An alternative theoretical scaling factor is proposed that gave an improved prediction of RHS impact response.
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Daneshvar, Sara. "Effects of design details on stress concentrations in welded rectangular hollow section connections." Thesis, 2021. http://hdl.handle.net/1828/12785.
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For fatigue design of welded hollow structural sections connections, the “hot spot stress method” in CIDECT Design Guide 8 is widely used. This method forms the basis of various national and international design standards. This thesis sought to address some contemporary design issues where the existing approaches cannot be directly applied. Modified design approaches were proposed for various practical design details.
For galvanizing of welded tubular steel trusses, sufficiently large holes to allow for quick filling, venting and drainage must be specified. These holes, quite often specified at the hot spot stress locations, will inevitably affect connection fatigue behaviour. In Chapter 1, six rectangular hollow section (RHS) connections were tested under branch axial loading. The stress concentration factors (SCFs) obtained from the experimental investigation were compared with those calculated using the formulae in CIDECT Design Guide 8. It was shown that the predictions based on the current formulae were unsafe. Hence, finite element (FE) models were developed and validated by comparison with the experimental data. A subsequent parametric study was conducted, including 192 FE models with different hole locations and non-dimensional parameters [branch-to-chord width (β), branch-to-chord thickness (τ), and chord slenderness (2γ) ratios]. SCF formulae for RHS connections with vent/drain holes at different locations were established based on the experimental and FE data. In Chapter 2, by modifying the 192 parametric models in Chapter 1, FE analysis was performed to examine the existing SCF formulae in CIDECT Design Guide 8 for RHS T-connections under branch in-plane bending. The parametric study showed that the existing SCF formulae can lead to unsafe predictions. Critical hot spot stress locations were thus identified. The effects of both branch in-plane bending and chord loading were studied. New design formulae that take the vent and drain holes into account were proposed.
The design rules in CIDECT Design Guide 8 assumes sufficient chord continuity on both sides of connection. Therefore, the existing formulae cannot be directly applied to RHS-to-RHS connections situated near a truss/girder end. Chapter 3 sought to develop new approach for calculation of SCFs in such connections. 256 FE models of RHS-to-RHS X-connections, with varied chord end distance-to-width (e/b0) and non-dimensional parameters were modelled and analyzed. The analysis was performed under quasi-static axial compression force(s) applied to the branch(es) and validated by comparison of strain concentration factors (SNCFs) to SNCFs obtained from full-sized connection tests. For all 256 connections, SCFs were determined at five critical hot spots on the side of the connection near the open chord end. The SCFs were found to vary as a function of e/b0, 2γ and β. Existing formulae in CIDECT Design Guide 8 to predict SCFs in directly welded RHS-to-RHS axially loaded X-connections were shown to be conservative when applied to a connection near an open chord end. SCF reduction factors (ψ), and a parametric formula to estimate ψ based on e/b0, 2γ and β, were derived. For RHS-to-RHS connections situated near a truss/girder end, reinforcement using a chord-end cap plate is common; however, for fatigue design, formulae in current design guidelines [for calculation of SCFs] cater to: (i) unreinforced connections, with (ii) sufficient chord continuity beyond the connection on both sides. Chapter 4 sought to develop definitive design guidelines for such connections. The parametric models in Chapter 3 were modified to simulate such connections. Existing SCF formulae in CIDECT Design Guide 8 were shown to be inaccurate if applied to cap plate-reinforced end connections. SCF correction factors (ψ), and parametric formulae to estimate ψ based on e/b0, β, τ and 2γ, were derived. The same methodology was used in Chapter 5 to study the SCFs in square bird-beak (SBB) and diamond bird-beak (DBB) tubular steel X-connections situated at the end of a truss or girder. A comprehensive parametric study, including 256 SBB and 256 DBB connection models, covering wide ranges of chord end distance-to-width (e/b0) and non-dimensional parameters, was performed. Two sets of correction factor (ψ) formulae for consideration of the chord end distance effect were derived, for SBB and DBB X-connections, respectively.Graduate
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Mikheeva, Margarita. "Numerical analysis of compressed components of beam-to-rectangular hollow section column moment resistant steel joints." Master's thesis, 2017. http://hdl.handle.net/10316/83228.
Full textAbstract:
Dissertação de Mestrado em Construção Metálica e Mista apresentada à Faculdade de Ciências e TecnologiaHollow sections appear to be very attractive from the architectural and structural point of view. They exhibit high aesthetic performance along with significant resistance to compression, bending and torsion. Additionally, hollow sections show higher durability and corrosion resistance comparing to opened sections.However, connecting to hollow sections is a demanding procedure. The absence of the access to the interior void of hollow sections leads to the necessity of developing appropriate types of joints which would allow to balance design, fabrication, erection and operation stages with the overall project cost.The range of possible connections of beams to hollow sections is already invented. Nevertheless, there is always a challenge to develop connection types with improved characteristics. The present thesis is a part of the wider research of beam-to-rectangular hollow section column moment resistant joint subjected mainly to the action of the bending moment. The main research project is divided into three parts, investigation of compressed components of the joint, tension components of the joint and the global joint. Each part contains experimental tests, numerical modeling and analytical characterization of the joint behaviour. The goal of the thesis is to investigate the behaviour of compressed components of the joint by numerical modeling. Numerical results are further validated by comparison to experimental data. Numerical simulations are carried out by DS Simulia Abaqus software. The thesis includes numerical analysis of four models corresponding to experimental specimens which represent compressed components of the joint. After the calibration of obtained results the parametric study is implemented for 104 numerical models more. The parametric study aims to investigate the behaviour of the components for the extended range of geometrical variation.The result of the present thesis is the information about resistance and stiffness of the compressed components of the joint based on the force - displacement response which is obtained for the total number of 108 numerical models.
Hollow sections appear to be very attractive from the architectural and structural point of view. They exhibit high aesthetic performance along with significant resistance to compression, bending and torsion. Additionally, hollow sections show higher durability and corrosion resistance comparing to opened sections.However, connecting to hollow sections is a demanding procedure. The absence of the access to the interior void of hollow sections leads to the necessity of developing appropriate types of joints which would allow to balance design, fabrication, erection and operation stages with the overall project cost.The range of possible connections of beams to hollow sections is already invented. Nevertheless, there is always a challenge to develop connection types with improved characteristics. The present thesis is a part of the wider research of beam-to-rectangular hollow section column moment resistant joint subjected mainly to the action of the bending moment. The main research project is divided into three parts, investigation of compressed components of the joint, tension components of the joint and the global joint. Each part contains experimental tests, numerical modeling and analytical characterization of the joint behaviour. The goal of the thesis is to investigate the behaviour of compressed components of the joint by numerical modeling. Numerical results are further validated by comparison to experimental data. Numerical simulations are carried out by DS Simulia Abaqus software. The thesis includes numerical analysis of four models corresponding to experimental specimens which represent compressed components of the joint. After the calibration of obtained results the parametric study is implemented for 104 numerical models more. The parametric study aims to investigate the behaviour of the components for the extended range of geometrical variation.The result of the present thesis is the information about resistance and stiffness of the compressed components of the joint based on the force - displacement response which is obtained for the total number of 108 numerical models.
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Aguilera, JOSE Jr. "Strengthening T-Joints of Rectangular Hollow Steel Sections Using Through-Wall Bolts and Externally Bonded FRP Plates." Thesis, 2012. http://hdl.handle.net/1974/7542.
Full textAbstract:
T-joints are common in beam-column connections of steel frames, vierendeel girders and at mid-span of N-trusses. Strengthening the members of these structures increases the demand on the joints, which may require joint strengthening. This thesis examines different strengthening techniques of T-joints of RHS members. In Phase I, the effectiveness of through-wall steel bolts is examined. This is accomplished by controlling the web outward buckling of the chord under the brace axial load. The study examined the effect of the number and pattern of bolts, as well as the web height-to-wall thickness (h/t) ratio of the chord, on strengthening effectiveness. Rectangular 203x76x(3.09, 4.5, and 5.92) mm chord members were tested. The 8 mm diameter steel bolts varied from a single bolt to 15 bolts of various distributions. The joint strength increased by 3.1%, 6.2%, and 29% for chords with (h/t) of 34, 45, and 65, respectively. The number and distribution of bolts had little effect on their effectiveness.
In Phase II, similar T-joint specimens were strengthened using adhesively bonded GFRP plates, 9.5 mm thick, of different configurations, and 2 mm thick high-modulus CFRP plates of equivalent stiffness. It was shown that strength gain increases significantly, from 9% to 38%, as (h/t) ratio of the HSS chord increases from 34 to 65. In thin-walled HSS (h/t = 65), retrofitting provided significant gains in strength but not in ductility. In thick-walled HSS (h/t = 34), retrofitting provided little strength gain, but enhanced ductility, especially with properly bonded plates extending on the brace. Generally, plates fractured under local bending or delaminated within plate layers while bond was fully intact.
In Phase III, selected configurations of the two retrofitting methods were used in additional T-joints with chord (h/t) ratio of 65, to study their effectiveness in presence of axial compression load in the chord. Two sustained load levels were induced in the chord, representing 45% and 80% of its full axial capacity. The transverse brace load was then gradually increased to failure. The through-wall steel bolts increased the joint capacity by 13% to 25%, depending on the chord’s axial load level, while the bonded GFRP plate increased the capacity by 38 to 46%.Thesis (Master, Civil Engineering) -- Queen's University, 2012-09-28 12:40:44.479
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Tsai, Wan-yun, and 蔡宛昀. "Development of a frame system containing rectangular hollow section columns." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26yzv9.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
100
Rectangular hollow section columns, manufactured by roll forming, are more economical than box columns. This can enhance the competitiveness of the steel buildings. If the rectangular hollow section columns are used in low to mid-rise buildings, the environmental protection concepts can be implemented. In this study, a internal diaphragm system and an external diaphragm-horizontal haunch system are proposed. And the seismic behavior of the two systems was evaluated through cyclic loading test of five beam - column sub-assemblage specimens. Experimental results show that: (1) Internal diaphragm system is feasible. (2) The external diaphragm-horizontal haunch system is also feasible. (3) Compared with internal diaphragm system, the external diaphragm-horizontal haunch system uses 44% less material and less welds. (4) Local buckling is retarded when the length of the horizontal haunch is smaller. (5) The cold forming process produces residual stresses at the corner of the rectangular hollow section. As a result, the commonly used welding procedure may cause premature crack at the corner of the column section. A suitable welding procedure should be established in the future research to prevent premature crack problem.
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Lin, Shu-Hao, and 林書豪. "Flexural Ductile Behavior of Larger BCR Rectangular Hollow Section Columns." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/48888449144913192600.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
103
In recent years, the production equipment of rectangular hollow section column substantially to increase, the size of rectangular hollow section column can also be significantly increased and are more economical than box column. Therefore, this can be already used in the high-rise steel buildings. But the cold forming process resulting in decreased ductility of rectangular hollow section column, so the toughness of the rectangular hollow section column should be test by structural testing. Rectangular hollow section column using an internal diaphragm system or an external diaphragm system and box column using the general internal diaphragm system made five beam-column sub-assemblage specimens to test their flexural ductile behavior. Experimental results showed that: (1) The external diaphragm system specimen, column and the corner of an external diaphragm system welds than the internal diaphragm system specimen, column and the upper flange of the beam welds even earlier cracks.(2) Rectangular hollow section column and beams joints, the straight line of rectangular hollow section column welding into the heat should be controlled in less than 40 kJ / cm, a corner of rectangular hollow section column welding into the heat should be controlled in less than 30 kJ / cm.(3) For the internal diaphragm system specimen, corner of diaphragm have notching, behavior of column plate by diaphragm supporting so poor and likely to cause local buckling deformation when the column is subjected to lateral force. The opposite of the external diaphragm system specimen, the column around the external diaphragm covering, column local buckling deformation will occur later.(4) Rectangular hollow section column made of cold-rolled forming, causing its strength than box columns.(5) Surround of box column full welding is easily to crack caused by buckling deformation. The opposite of surround of rectangular hollow section column isn’t to crack caused by buckling deformation.(6) For same column section, the real b/t (width to thickness ratio) of box column is larger than the real b/t of rectangular hollow section column. Therefore, when we choose rectangular hollow section column section, we need to understand the real b/t of rectangular hollow section column calculated and the real b/t of box column in different ways to calculate.
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Ma, Zhengyuan. "Mechanical properties of heat-treated and hot-dip galvanized rectangular hollow section material." Thesis, 2018. https://dspace.library.uvic.ca//handle/1828/10411.
Full textAbstract:
Hot-dip galvanizing is widely used for corrosion protection of steel structures. However, there has been a plethora of recent reports on premature cracking in galvanized steel structures, which have resulted in some early decommissions or even hazardous collapses. This research focuses on cold-formed Rectangular Hollow Sections (RHS). A total of 108 tensile coupons were tested to investigate the effects of galvanizing as well as different pre-galvanizing treatments on the material properties around the cross sections of the specimens. For the first time, this thesis reports a comprehensive measurement of residual stresses in different directions at the member ends which are directly relevant to the cracking issue. The results were also compared to the residual stresses far away from the member ends, which are relevant to structural stability research. In all, the research provides a better understanding of the characteristics and structural performance of galvanized RHS to facilitate its application. The recommendations can help engineers, fabricators, and galvanizers mitigate the risk of cracking in RHS during galvanizing.Graduate
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Tayyebi, Kamran. "Behaviour and design of direct-formed hollow structural section members." Thesis, 2021. http://hdl.handle.net/1828/13096.
Full textAbstract:
In North America, cold-formed square and rectangular hollow sections (collectively referred to as RHS hereinafter) of commonly specified cross-sectional dimensions are produced using either the indirect-forming approach or the direct-forming approach. The indirect-forming approach, as the conventional approach of the two, consists of three steps: (i) roll-forming the coil material progressively into a circular hollow section; (ii) closing the section using electric resistance welding (ERW); and (iii) reshaping the circular section into the final square or rectangular shape. On the other hand, the direct-forming approach, as the new approach of the two, roll-forms the coil material directly into the final square or rectangular shape.
RHS with similar cross-sectional dimensions but different production histories (i.e., different cold-forming approaches and post-production treatments) are expected to have significantly different material and residual stress properties. However, RHS design provisions in the existing North American steel design standards (AISC 360-16 and CSA S16-19) are in general developed based on research on indirect-formed RHS and currently do not differentiate RHS cold-formed by different approaches. Based on the research presented in Chapter 1 of this thesis, comparing to indirect-formed RHS, direct-formed RHS in general contain lower levels of residual stresses around cross sections, since the flat faces are not severely cold worked during production. This in turn affects member behaviours under compressive and flexural loadings. The test results presented in Chapters 2 and 4 show that direct-formed RHS have superior stub column and beam behaviours, comparing to their indirect-formed counterparts. In particular, the stub column and beam testing programs, covering a wide range of cross-section dimensions and two strength grades (nominal yield stresses of 350 and 690 MPa), show that the slenderness limits in the existing North American steel design standards are excessively conservative for direct-formed RHS, resulting in unnecessary penalty and member strength underestimation. As a result, the existing design formulae are not suitable for direct-formed RHS. In response to this, subsequent finite element (FE) parametric investigations are performed and presented in Chapters 3 and 5. Modified stub column and beam design recommendations for direct-formed regular- and high-strength RHS are proposed.
The effects of post-cold-forming hot-dip galvanizing on material properties, residual stresses, stub column behaviours and beam behaviours of direct-formed regular- and high-strength RHS are also studied in Chapters 1-5 of this thesis. Similar to the application of the heat treatment per ASTM A1085 Supplement S1 or the Class H finish per CSA G40.20/G40.21, post-cold-forming galvanizing improves the stub column (Chapter 2) and beam (Chapter 4) behaviours of direct-formed RHS via effective reduction of residual stresses (Chapter 1). Based on subsequent FE parametric investigations, modified stub column and beam design recommendations catering to galvanized direct-formed RHS are proposed in Chapters 3 and 5.Graduate
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McFadden, Matthew. "Effective Weld Properties for RHS-to-RHS Moment T-connections." Thesis, 2012. http://hdl.handle.net/1807/33446.
Full textAbstract:
An experimental program was developed to test various unreinforced RHS-to-RHS 90° T-connections subject to branch in-plane bending moment with the objective of determining the effectiveness of the welded joint. Twelve unique test specimens were designed to be weld-critical and the results from the full-scale tests revealed that the current equation for the effective elastic section modulus for in-plane bending, S_ip, given in Table K4.1 of ANSI/AISC 360 (2010) is conservative. A modification to the current requirements that limit the effective width of the transverse weld elements is proposed, resulting in a safe and more economical weld design method for RHS-to-RHS T-, Y- and X- connections subject to branch axial load or bending moment. It is also concluded that the fillet weld directional strength enhancement factor, (1.00 + 0.50sin1.5Ө), should not be used for strength calculations of welded joints to square and rectangular hollow structural sections.