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1
Abdel-Rahman, Nabil Mahmoud. "Cold-formed steel compression members with perforations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30065.pdf.
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Cheng, Shanshan. "Fire performance of cold-formed steel sections." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3316.
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Thin-walled cold-formed steel (CFS) has exhibited inherent structural and architectural advantages over other constructional materials, for example, high strength-to-weight ratio, ease of fabrication, economy in transportation and the flexibility of sectional profiles, which make CFS ideal for modern residential and industrial buildings. They have been increasingly used as purlins as the intermediate members in a roof system, or load-bearing components in low- and mid-rise buildings. However, using CFS members in building structures has been facing challenges due to the lack of knowledge to the fire performance of CFS at elevated temperatures and the lack of fire design guidelines. Among all available design specifications of CFS, EN1993-1-2 is the only one which provided design guidelines for CFS at elevated temperatures, which, however, is based on the same theory and material properties of hot-rolled steel. Since the material properties of CFS are found to be considerably different from those of hot-rolled steel, the applicability of hot-rolled steel design guidelines into CFS needs to be verified. Besides, the effect of non-uniform temperature distribution on the failure of CFS members is not properly addressed in literature and has not been specified in the existing design guidelines. Therefore, a better understanding of fire performance of CFS members is of great significance to further explore the potential application of CFS. Since CFS members are always with thin thickness (normally from 0.9 to 8 mm), open cross-section, and great flexural rigidity about one axis at the expense of low flexural rigidity about a perpendicular axis, the members are usually susceptible to various buckling modes which often govern the ultimate failure of CFS members. When CFS members are exposed to a fire, not only the reduced mechanical properties will influence the buckling capacity of CFS members, but also the thermal strains which can lead additional stresses in loaded members. The buckling behaviour of the member can be analysed based on uniformly reduced material properties when the member is unprotected or uniformly protected surrounded by a fire that the temperature distribution within the member is uniform. However if the temperature distribution in a member is not uniform, which usually happens in walls and/or roof panels when CFS members are protected by plaster boards and exposed to fire on one side, the analysis of the member becomes very complicated since the mechanical properties such as Young’s modulus and yield strength and thermal strains vary within the member. This project has the aim of providing better understanding of the buckling performance of CFS channel members under non-uniform temperatures. The primary objective is to investigate the fire performance of plasterboard protected CFS members exposed to fire on one side, in the aspects of pre-buckling stress distribution, elastic buckling behaviour and nonlinear failure models. Heat transfer analyses of one-side protected CFS members have been conducted firstly to investigate the temperature distributions within the cross-section, which have been applied to the analytical study for the prediction of flexural buckling loads of CFS columns at elevated temperatures. A simplified numerical method based on the second order elastic – plastic analysis has also been proposed for the calculation of the flexural buckling load of CFS columns under non-uniform temperature distributions. The effects of temperature distributions and stress-strain relationships on the flexure buckling of CFS columns are discussed. Afterwards a modified finite strip method combined with the classical Fourier series solutions have been presented to investigate the elastic buckling behaviour of CFS members at elevated temperatures, in which the effects of temperatures on both strain and mechanical properties have been considered. The variations of the elastic buckling loads/moments, buckling modes and slenderness of CFS columns/beams with increasing temperatures have been examined. The finite element method is also used to carry out the failure analysis of one-side protected beams at elevated temperatures. The effects of geometric imperfection, stress-strain relationships and temperature distributions on the ultimate moment capacities of CFS beams under uniform and non-uniform temperature distributions are examined. At the end the direct strength method based design methods have been discussed and corresponding recommendations for the designing of CFS beams at elevated temperatures are presented. This thesis has contributed to improve the knowledge of the buckling and failure behaviour of CFS members at elevated temperatures, and the essential data provided in the numerical studies has laid the foundation for further design-oriented studies.
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Tran, Tuan D. "Global optimisation of cold-formed steel sections." Thesis, Aston University, 2007. http://publications.aston.ac.uk/12239/.
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In this thesis, standard algorithms are used to carry out the optimisation of cold-formed steel purlins such as zed, channel and sigma sections, which are assumed to be simply supported and subjected to a gravity load. For zed, channel and sigma section, the local buckling, distortional buckling and lateral-torsional buckling are considered respectively herein. Currently, the local buckling is based on the BS 5950-5:1998 and EN 1993-1-3:2006. The distortional buckling is calculated by the direct strength method employing the elastic distortional buckling which is calculated by three available approaches such as Hancock (1995), Schafer and Pekoz (1998), Yu (2005). In the optimisation program, the lateral-torsional buckling based on BS 5950-5:1998, AISI and analytical model of Li (2004) are investigated. For the optimisation program, the programming codes are written for optimisation of channel, zed and sigma beam. The full study has been coded into a computer-based analysis program (MATLAB).
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Chu, Xiao-ting. "Failure analysis of cold-formed steel sections." Thesis, Aston University, 2004. http://publications.aston.ac.uk/12234/.
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The purlin-sheeting system has been the subject of numerous theoretical and experimental investigations over the past 30 years, but the complexity of the problem has led to great difficulty in developing a sound and general model. The primary aim of the thesis is to investigate the failure behaviours of cold-formed zed and channel sections for use in purlin-sheeting systems. Both the energy method and finite strip method are used to develop an approach to investigate cold-formed zed and channel section beams with partial-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load. The stress analysis of cold-formed zed and channel section beams with partially-lateral restraint from the metal sheeting when subjected to a uniformly distributed transverse load is investigated firstly by using the analytical model based on the energy method in which the restraint actions of the sheeting are modelled by using two springs representing the translational and rotational restraints. The numerical results have showed that the two springs have significantly different influences on the stresses of the beams. The influence of the two springs has also been found to depend on the anti-sag bar and the position of the loading line. A novel method is presented for analysing the elastic local buckling behaviour of cold-formed zed and channel section beams with partial-lateral restraint from metal sheeting when subjected to a uniformly distributed transverse load, which is carried out by inputting the cross sectional stresses with the largest compressive stress into the finite strip analysis. By using the presented novel method, individual influences of warning stress, partially lateral restraints from the sheeting and the dimensions of the cross section and position of the loading line on the buckling behaviour are investigated.
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Mahdavian, Mahsa. "Innovative Cold-Formed Steel Shear Walls with Corrugated Steel Sheathing." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849608/.
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This thesis presents two major sections with the objective of introducing a new cold-formed steel (CFS) shear wall system with corrugated steel sheathings. The work shown herein includes the development of an optimal shear wall system as well as an optimal slit configuration for the CFS corrugated sheathings which result in a CFS shear wall with high ductility, high strength, high stiffness and overall high performance. The conclusion is based on the results of 36 full-scale shear wall tests performed in the structural laboratory of the University of North Texas. A variety of shear walls were the subject of this research to make further discussions and conclusions based on different sheathing materials, slit configurations, wall configurations, sheathing connection methods, wall dimensions, shear wall member thicknesses, and etc. The walls were subject to cyclic (CUREE protocol) lateral loading to study their deformations and structural performances. The optimal sit configuration for CFS shear walls with corrugated steel sheathings was found to be 12×2 in. vertical slits in 6 rows. The failure mode observed in this shear wall system was the connection failure between the sheathing and the framing members. Also, most of the shear walls tested displayed local buckling of the chord framing members located above the hold-down locations. The second section includes details of developing a Finite Element Model (FEM) in ABAQUS software to analyze the lateral response of the new shear wall systems. Different modeling techniques were used to define each element of the CFS shear wall and are reported herein. Material properties from coupon test results are applied. Connection tests are performed to define pinching paths to model fasteners with hysteretic user-defined elements. Element interactions, boundary conditions and loading applications are consistent with full scale tests. CFS members and corrugated sheathings are modeled with shell elements, sheathing-to-frame fasteners are modeled using nonlinear springs (SPRING2 elements) for monotonic models and a general user defined element (user subroutine UEL) for cyclic models. Hold-downs are defined by boundary conditions. A total of three models were developed and validated by comparing ABAQUS results to full scale test results.
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Yu, Guowang. "Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271921/.
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Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This research is aimed at developing modifications on the corrugated sheathing to improve the ductility of the shear wall as well as derive practical response modification factor by establishing correct relationship between ductility factor ? and response modification factor R. Totally 21 monotonic and cyclic full-scale shear wall tests were conducted during the winter break in 2012 by the author in NUCONSTEEL Materials Testing Laboratory in the University of North Texas. The research investigated nineteen 8 ft. × 4 ft. shear walls with 68 mil frames and 27 mil corrugation sheet steel in 11 configurations and two more shear walls sheathed with 6/17-in.OSB and 15/32-in. plywood respectively for comparison. The shear walls, which were in some special cutting arrangement patterns, performed better under lateral load conditions according to the behavior of ductility and shear strength and could be used as lateral system in construction.
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Feng, Ran, and 馮然. "Design of cold-formed stainless steel tubular joints." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41290628.
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Lim, James B. P. "Joint effects in cold-formed steel portal frames." Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368970.
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Kyvelou, Pinelopi. "Structural behaviour of composite cold-formed steel systems." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/50694.
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The topic of this thesis is the investigation of the structural behaviour of cold-formed steel flooring and purlin systems, taking into consideration the beneficial effect of interaction between structural components. Experiments have been conducted on flooring systems comprising cold-formed steel joists and wood-based particle boards, considering the typical screw fixings employed in current practice as well as alternative means of shear connection. The experimental findings showed that mobilisation of composite action within this type of system, through enhancement, beyond that currently used, of the employed shear connection, is feasible, bringing corresponding increases in capacity and stiffness. In order for the influence of the key parameters to be further examined, a finite element model simulating the examined systems has been developed, validated and employed for parametric studies. Analyses confirmed the experimental findings, showing that significant benefits in terms of capacity and stiffness can be achieved, especially for systems comprising thinner steel sections. Based on the obtained experimental and numerical results, a full design method, following the fundamental concepts of current design codes for composite structures, has been devised, providing accurate predictions of moment capacity and flexural stiffness. Finally, a numerical investigation has been performed on continuous two-span roof systems comprising cold-formed steel purlins, accounting for their interaction with the corrugated sheeting. The study showed that moment redistribution is possible within these systems, but usually accompanied by a reduction of the moment capacity of the central support. A previously devised method for the design of continuous purlin systems, making direct use of cross-section capacities at key locations, together with a factor to allow for the fall-off in moment at the central support, has been assessed and advanced.
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Hui, Chi. "Moment redistribution in cold-formed steel purlin systems." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/25533.
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The external envelope of steel framed industrial buildings normally involves the use of purlins and rails spanning between the main hot-rolled frames to support the roofing/cladding. These purlins are typically light-gauge cold-formed steel members of complex shape for which the thinness of the material means that local instabilities will significantly influence their structural behaviour. In this thesis, the finite element (FE) method (ABAQUS) has been used to develop numerical analyses to study the buckling behaviour and degree of moment redistribution in continuous and sleeved cold-formed steel 2-span purlin systems. Five types of nonlinear FE analyses have been validated against reported physical tests: (i) continuous 2-span beams subjected to uniformly distributed load (UDL), (ii) single span beams subjected to a moment gradient, (iii) single span beams subjected to pure bending (iv) sleeved 2-span beams subjected to a UDL and (v) single span sleeved sections subjected to a moment gradient. The FE analyses were used to generate a large portfolio of new results for gravity and uplift loading for continuous and sleeved 2-span arrangements covering a wide range of cross-sections by varying the flange and web dimensions and material thickness. The effects of local and distortional buckling and limited rotational capacities for single span FE models were investigated. The 2-span FE results formed the basis for a simple modification to conventional plastic design that recognises the possibility of a reduction in moment with increasing rotation in the interior support region. The assumption of full moment redistribution for gravity loading was found to be only valid for stocky sections but not for slender sections. For uplift loading in addition to the potential reductions in moment at the interior support, limitations in the span moment due to lateral torsional buckling (LTB) for slender members were also accounted for. Based on the FE results, an α-reduction framework was established to predict the collapse load for continuous and sleeved 2-span systems. It was assumed that the cross-section or LTB resistance was achieved in the span while a reduced cross-section resistance allowing for the post-peak fall in capacity was achieved at the interior support. The accuracy of the proposed design method was compared against elastic and full plastic design cases by considering their ultimate load carrying capacities. Whereas the elastic design method provides overly-conservative results and plastic design overestimates the capacity of slender sections, the proposed design method gave accurate predictions of the failure load with minimal scatter for all cases. The developed α-reduction framework provides a foundation for allowing the use of other purlin sections and interior support connections by inserting alternative cross-sectional moment capacity inputs obtained from several sources such as physical testing, hand calculations from design codes and FE analyses.
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Ganesan, Karthik. "Resistance Factor for Cold-Formed Steel Compression Members." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33694.
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This research investigates if the LRFD strength reduction factor for cold-formed steel compression members can be increased above its current value of Ï c = 0.85, which was established by the LRFD Cold-Formed Steel Design Manual (1991) on the basis of 264 column tests. The resistance factor in the Canadian code for cold-formed steel compression members is also evaluated. A total of 675 concentrically loaded plain and lipped C-section columns, plain and lipped Z-section columns, hat and angle columns, including members with holes, are considered in the study. The predicted strengths are calculated with the AISI-S100-07 Main Specification and the AISI Direct Strength Method. The test-to-predicted strength statistics are employed with the first order second moment reliability approach in AISI-S100-07 Chapter F as well as a higher order method to calculate the resistance factor per cross-section type, ultimate limit state, and considering partially and fully effective columns. The observed trends support a higher resistance factor for columns buckling in a distortional buckling limit state and an expansion of the current DSM prequalified limits. The results also show that DSM predicts the column capacity more accurately than the Main Specification. The test-to-predicted ratios for plain and lipped angle columns exhibit a high coefficient of variation and become more and more conservative as global slenderness increases. It is concluded that fundamental research on the mechanics of angle compression members is needed to improve existing design methods.Master of Science
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Soroori, Rad Behrooz H. "Experiments on Cold-Formed Steel Beams with Holes." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/42698.
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Experimental testing and elastic buckling studies were performed on 68 C-section cold-formed steel joists with unstiffened rectangular web holes. Four Steel Stud Manufacturers Association (SSMA) cross-section types; 800S200-33, 800S200-43, 1000S162-54, and 1200S162-97, were evaluated to explore the influence of holes on local, distortional, and global bucking failure modes. Hole depth was varied in the tests to identify trends in ultimate strength. Ultimate strength was observed to decrease with increasing hole depth for 800S200-33, 1200S162-97 cross-sections. Due to small number of specimen and unidentified behavior of the beams, a more in depth study of the behavior of 800S200-43 and 1000S162-54 beams are necessary. Local buckling of the unstiffened strip above the hole was observed to accompany distortional buckling at the hole for the locally slender 800S200-33 and 1000S162-54 cross-sections. Thin shell finite element eigen-buckling analysis of each joist specimen, including measured cross-section dimensions and tested boundary and loading conditions, were conducted in parallel with the experiments to identify those elastic buckling mode shapes which influence load-deformation response. The distortional and lateral-torsional buckling moments were observed to decrease with increasing hole depth while a contrasting behavior was captured for local buckling modes. A modification to the AISI Direct Strength Method equations for beams with slotted web-holes was compared against the experimental results with predictions lower than tested strength. Initial cross-section imperfections led to inclined webs which decreased the capacity of the beams. The use of a water-jet cutting process was employed successfully to produce accurate holes sizes and locations in each joist specimen and is recommended for researchers and manufacturers as a method for custom fabrication of cold-formed steel members.Master of Science
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Feng, Ran. "Design of cold-formed stainless steel tubular joints." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41290628.
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Huynh, Minh Toan. "Structural Behaviour of Cold-Formed Steel Screwed Connections." Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/22098.
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This thesis presents a study on the behaviour of connections using screws in cold-formed steel structures. The first part of the thesis studies the behaviour of the screw connectors using simple connection tests and Finite Element (FE) modelling. Specimens were assembled by using 2 or 3 screws connecting two cold-reduced sheet steels with various grades and thicknesses. Two types of limit states were investigated: (i) screw shear failure and (ii) bearing and tilting failure. A set of revised design equations for strength of screwed connections in bearing and tilting is proposed. A reliability analysis is performed using the proposed equations, which allow for an improvement in the capacity reduction factor in current design standards. Furthermore, an FE model, which contains fracture characteristics of both the screws and the sheet steels, is developed to give better understanding of the screw behaviour with respect to different limit states. In the second stage of the research, a dual-actuator test apparatus was set up in order to test shear connections from cold-formed steel channels to hollow sections. Each connection contained an angle cleat and two screws. Different amount of shear force and connection rotation to transfer into the connection in each test. Two limit states involving failure of the screws and failure of the sheets were investigated. Finally, an analytical model for the connection is developed using the relation between bearing force and deformation of individual screws from the first stage of the thesis. An FE model is also developed, which demonstrates how to apply actual geometry of the screws into a simulation at a structure scale. It is concluded that a simple connection carrying shear with bearing and tilting failure mode has better strength conserving capability when dealing with high rotation compared with a connection with shear fracture of the screws.
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Niu, Shuang. "Interaction Buckling of Cold-Formed Stainless Steel Beams." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11541.
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The research investigates the interaction between sectional and global buckling of cold-formed stainless steel beams. Two separate experimental programs were carried out. The first program was on I sections, reflecting the local-global interaction buckling behavior, while the second program studied distortional-global interaction buckling in lipped channel beams. Three alloys were included: austenitic S30401(304), ferritic S44330(443) and lean duplex S32101(2101), for which extensive material tests were carried out to determine the material properties. Efforts were made to create a test rig which offered clearly defined support and loading conditions. A detailed finite element (FE) model was developed, incorporating actually measured material properties, imperfections and boundary conditions. The FE model was verified against the experimental results, and then was used in a parametric study to extend the experimental database. Practical ranges of overall and cross-sectional slenderness values were covered in the parametric study, and more concise boundary conditions were used to afford data better suited for further theoretical study. The current Australian, American and European design provisions for cold-formed stainless steel beams were evaluated with the parametric study results. All the design codes were found to be unsafe for I-section beams with intermediate or high local buckling slenderness. For lipped channel sections, the Australian and American design codes were reasonably accurate for a distortional slenderness of unity, but were optimistic for a higher distortional slenderness of 1.5. Contrarily, the European code yielded generally better predictions for the high distortional slenderness sections but was quite conservative for low slenderness sections. New design formulae in the form of the Direct Strength Method were proposed according to the existing strength database.
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N'emedi, Zsolt V. "Development of performance sections for cold-formed steel residential construction." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08222009-040502/.
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Zhou, Feng. "Web crippling of cold-formed stainless steel tubular sections." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37228316.
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Zhang, Jiahui, and 张佳慧. "Cold-formed steel built-up compression members with longitudinal stiffeners." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206457.
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In this study, the structural behaviour of cold-formed steel built-up compression members with longitudinal stiffeners was investigated by experiments and numerical simulation. The influence of different screw spacings on the ultimate strengths of built-up compression members was also investigated. In current design specifications, generally there are no direct and explicit design rules for cold-formed steel built-up sections. Therefore, design rules for built-up open sections and closed sections have been proposed.
The test program was conducted for cold-formed steel built-up sections, which were compressed axially between fixed ends with various column lengths ranged from 300 to 3200 mm. Two identical open sections were connected by self-tapping screws to form a built-up section. The material properties and initial geometric imperfections of the test specimens were measured. The experimental investigation consisted of built-up open sections with edge and web stiffeners, and built-up closed sections with inward or outward web stiffeners. In total, 47 specimens were tested with a screw spacing of 100 mm, and another 25 specimens were tested with screw spacings of 300 and 600 mm.
A further investigation on the structural behaviour of cold-formed steel built-up compression members was performed using finite element analysis (FEA). Firstly, accurate and reliable finite element models (FEMs) were developed and verified against the test results. Secondly, extensive parametric studies of cross-section geometry and the screw spacing were carried out by the verified FEMs. The parametric study contained 442 specimens for built-up open sections, built-up closed sections, and built-up sections with different screw spacings. Therefore, the complex structural behaviour of built-up compression members with edge and web stiffeners, together with different spacings of self-tapping screws were studied thoroughly, as reported in this thesis.
The current direct strength method (DSM) is a favored design method for cold-formed steel columns and beams due to its ease of calculation. However, DSM does not cover the design of cold-formed steel built-up sections. The appropriateness of DSM for cold-formed steel built-up compression members was accessed by both experimental and numerical investigation. It was found that the current DSM is not quite suitable for the design of built-up compression members. Therefore, the current DSM was modified for built-up open and closed sections. The results show that the modified design rules are generally conservative and reliable for the design of built-up compression members. In addition, design recommendations are proposed for built-up sections with different screw spacings. The reliability of the current and modified design rules was evaluated using reliability analysis.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
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Zhou, Feng, and 周鋒. "Web crippling of cold-formed stainless steel tubular sections." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37228316.
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Ye, Jun. "More efficient cold-formed steel elements and bolted connections." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/15276/.
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Modern society is challenged by economic and environmental issues, requiring engineers to develop more efficient structures. Using cold-formed steel (CFS) frame in construction industry can lead to more sustainable design, since it requires less material to carry the same load compared with other materials. However, the application of CFS structural systems is limited to low story buildings due to the inherent weaknesses of premature buckling behaviour of members and the low ductility of connections. Consequently, current design guidelines of CFS systems are very conservative especially in the case of seismic design. Furthermore, there is no generic optimisation framework for the CFS elements, capable of taking into account both manufacturing/construction constraints and post-buckling behaviour. This study aims to better understand, to predict, and to optimise CFS elements based on their strength and post-buckling behaviour. The optimised elements can be then included in full-structure modelling to develop more efficient CFS structural connections with high ductility and energy dissipation capacity, suitable for multi-story buildings in seismic regions. The geometrical dimensions of manufacturable CFS cross-sections were optimised regarding their maximum compressive and bending strength. All the sections were considered to have a fix coil width and thickness while the optimisation was performed based on effective width method suggested in EC3. The optimised solutions were achieved using Particle Swarm Optimisation (PSO) algorithm. The accuracy of the optimisation procedure was assessed using experimentally validated nonlinear Finite Element (FE) analyses accounting for the effect of imperfections To allow for the development of a new ‘folded-flange’ beam cross-section, the effective width method in EC3 was extended to deal with the presence of multiple distortional buckling modes. Improved strength were achieved for CFS elements by using the proposed optimisation framework. A non-linear shape optimisation method was presented for the optimum design of CFS beam sections based on their post-buckling behaviour. A developed PSO algorithm was linked to the ABAQUS finite element programme for inelastic post-buckling analysis and optimisation. The results also demonstrate that the optimised sections develop larger plastic area, which is particularly important in seismic design of moment-resisting frames. An experimental programme was carried out at the University of Sheffield to investigate the design and optimisation, considering interactive buckling in cold-formed steel channels under compression and bending. Both standard and optimised sections were tested. The specimen imperfections were measured using a specially designed set-up with laser displacement. Material tests were also carried out to determine the tensile properties of the flat plate and of the cold-worked corners. A total of 36 columns with three lengths and 6 back-to-back beams were completed. The column specimens were tested under a concentrically applied load and with pin-ended boundary conditions while the beams were tested in a four-point bending configuration. Based on the tests, numerical models were proposed and calibrated and the proposed optimisation framework was verified. A numerical study on the structural behaviour of CFS bolted beam-to-column connections under cyclic loading was presented. An innovative two node element which can take into account the slippage-bearing effects was proposed and implemented using an ABAQUS user defined subroutine. The connection performance in terms of strength, ductility, energy dissipation capacity and damping coefficient were investigated. The effects of bolt configuration, cross-sectional shapes and thicknesses on the connection performance were therefore examined. It is indicated that the proposed numerical model is robust and computationally efficient to simulate the failure modes and moment-rotation response of CFS bolted moment resisting connections.
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Zhao, Yanxia 1975. "Cyclic performance of cold-formed steel stud shear walls." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29553.
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This thesis contains a summary of previous cold-formed steel stud shear wall test programs in North America, as well as an overview of the seismic requirements for a number of different design standards, i.e. the NBCC, the UBC and the NEHRP guidelines for seismic design. A theoretical method for the prediction of shear capacity based on the first possible failure mode, which follows the adapted American wood design procedure, is presented and the results from this method are compared with peak loads obtained from existing tests. In addition, a preliminary force modification factor for use in seismic design is suggested for use with the NBCC. Finally, future tests of cold-formed steel stud shear walls are proposed and a corresponding test frame is designed. (Abstract shortened by UMI.)
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Zhang, Hanwen. "Connections in cold-formed steel modular building structure systems." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8181/.
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Modular construction has been used for many years. Cold-formed steel with its advantages is commonly utilized in the modules. However, the challenge comes to the connections. Connections generally take substantial part of the expenditures. An easy erection and effective connection method could considerably achieve great cost saving and structural improvement. Current norms and specifications cannot cover the requirements in the design. This research investigated the connections in the cold-formed steel modular panel structure through experimental, analytical and numerical methods. FEMs were developed to predict the behaviours of the purlin-to-sheeting, stud-to-track and joist-to-post connections. A modified calculation method for the rotational stiffness of purlin-to-sheeting connection was proposed. This research also carried out parametric studies to figure out the influence of variables on connection performance. In the investigation, a series of tests about screw and bolt joints under pure and mixed loading scenarios were conducted. The results of the established FE models presented a great accordance with the test outcomes. The connection configurations applied in cold-formed steel panel system with high strength material were introduced in this research. It was proved that the proposed connecting methods can provide great improvement to the structural behaviour under normal and abnormal loading conditions.
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Li, Huan. "Damage and repair evolution of cold formed linepipe steel." Thesis, University of Birmingham, 2010. http://etheses.bham.ac.uk//id/eprint/671/.
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The main aim of this research is to model the internal micro damage accumulated during cold deformation and the degree of reduction of damage that can be achieved by heat treatment of linepipe steel. A set of unified viscoplastic constitutive equations was developed to simulate microstructural evolution and the effect on mechanical properties due to cold deformation followed by annealing. In addition, practical experiments have been performed to validate the constitutive equations. Firstly, the industrial motivation for the project was previewed and damage-modelling techniques were reviewed to identify the research objectives. A group of interrupted uniaxial tensile tests were conducted to study the effect of different annealing times on reducing the degree of damage and improving mechanical properties of a cold formed single phase linepipe steel. From the experimental results, it was observed that healing by subsequent annealing enables a significant improvement in the mechanical properties of the deformed steel that has experienced only light damage, but has no significant effect on heavily damaged steel. Following this, a set of constitutive equations describing accumulation and annihilation of dislocations, grain size evolution, recrystallisation, plasticity induced damage and their effects on viscoplastic flow of materials was developed, for uniaxial stress conditions and by numerical integration experimental results were used to determine material constants for these equations, for the particular steel. Secondly, the constitutive equations were expanded to enable damage nucleation, growth and plastic flow to be predicted for various stress states. The constitutive equations were implemented in a commercial FE solver (ABAQUS) using the VUMAT user-subroutine. The numerical results reproduce the essential features of necking phenomena and provide a physical insight into damage evolution within a tensile testpiece under given necking conditions. Dual phase steel is of greater importance industrially, than a single phase steel, but because of the greater complexity in its microstructure, the development of microstructural constitutive equations for it is very difficult. Thus, in this work, some knowledge of damage initiation in a dual phase steel was obtained by practical investigation of microstructure. It showed that damage is due to ductile cracking characterised by the nucleation of micro-voids near the ferrite-pearlite interface. Using the mesoscopic modelling technique, by simulation, it was possible to determine likely sites for damage initiation.
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Tian, Yisheng. "Optimal design of cold-formed steel sections and panels." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615924.
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Afshan, Sheida. "Structural behaviour of cold-formed stainless steel tubular members." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23660.
Full textAbstract:
This thesis examines the behaviour of cold-formed stainless steel tubular structural members, with an emphasis on ferritic stainless steels. Owing to the high comparative expense of stainless steel relative to traditional carbon steel, this study aims to identify and develop means of utilising the material more efficiently. A comprehensive material test programme was carried out as part of an extensive study into the prediction of strength enhancements in cold-formed structural sections that arise during production. Material tests on a total of 51 flat coupons and 28 corner coupons, extracted from a total of 18 cross-sections formed from a wide range of materials, were performed. A new, simple and universal predictive model for harnessing the cold-formed induced strength enhancements was developed which offers, on average, 19% and 36% strength enhancements for the cross-section flat faces and corner regions, respectively, relative to the strength of the unformed material. Ferritic stainless steels, having no or very low nickel content, offer a more viable alternative for structural applications to the more commonly used austenitic stainless steels, reducing both the level and variability of the initial material cost. There is currently limited information available on the structural performance of this type of stainless steel. Therefore, to overcome this limitation, a series of material, cross-section and member tests have been performed on two ferritic grades - EN 1.4003 and EN 1.4509. The experimental results were used to assess the applicability of the current codified design provisions to ferritic stainless steel structural components. Moreover, the elevated temperature performance of ferritic stainless steels, covering the material response and the flexural buckling behaviour, was investigated through analysis of experimental and numerical results, leading to proposals for suitable design recommendations. Finally, simplifications and refinements to the recently developed continuous strength method (CSM) were made. Comparison of the predicted capacities with over 140 collected test results on stainless steel stub columns and cross-sections in bending shows that the CSM offers improved accuracy and reduced scatter relative to the current design methods. The reliability of the approach has been demonstrated by statistical analyses, enabling its use in structural design standards.
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Li, Xun. "Cold-Formed Steel Member Connections Using BAC Screw Fasteners." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505166/.
Full textAbstract:
In this project, the main research objective is intend to seek criteria for evaluating the capacity of BAC screw fasteners with mixed configuration of waterproof seal washer, sealer tape and different pre-drill holes to determine shear and tension strength values for the screws used in cold-formed steel connections. The thesis presents the design methods and test program conducted to investigate the behavior and strength of the screw connections in shear and tension test. Test results were compared with AISI design provisions to determine if new design equations will be developed for those screws used in BAC cooling tower applications. LRFD resistance factors and ASD safety factors were investigated to the proposed design equations.
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Blum, Hannah Beth. "Long-Span Cold-Formed Steel Double Channel Portal Frames." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16290.
Full textAbstract:
A comprehensive study on long-span cold-formed steel portal frames composed of back-to-back channel sections is presented. The aim of the study is to determine appropriate design guidelines in order for engineers to safely and efficiently build larger frames. The system analyzed herein is a haunched portal frame with a knee brace connected between the column and rafter. The objectives of the research were achieved through an extensive experimental study as well as numerical investigations. A comprehensive experimental program was completed to determine the strength and behavior of the frames. A total of nine full scale portal frame systems were tested, eight of which had unbraced columns. Variations to the frame layout, including modifications to the knee connection and the addition of sleeve stiffeners, were tested for both vertical and combined wind and vertical loading conditions. Column base rotational stiffness was quantified in the full scale experiments and in separate component tests. An advanced shell finite element model was created and calibrated with measured material and sections properties and column base stiffness, and was validated with the experimental results. A parametric study was completed to determine the effects of various configurations of the knee brace connection, as well as column base stiffness, on frame ultimate load. A larger span model was created to determine the suitability of the frame design for larger spans. A design procedure was developed to determine frame design loads. An energy method approach was employed to calculate the elastic buckling capacity of the column, which considers the elastic torsional restraint provided by the knee connection. A calibrated beam element model was used to determine the internal actions of the frame. A reliability check was completed and it was determined that the developed design method is suitable to design cold-formed steel portal frames.
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Panyanouvong, Mark. "Bearing Strength of Cold Formed Steel Bolted Connections in Trusses." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115135/.
Full textAbstract:
The existing design provision in North American Specification for Cold- Formed Steel Structural Member (AISI S100) for the bearing strength of bolted connections were developed from tests on bolted connected sheets which were restrained by bolt nut and head with or without washers. However, in the cold-formed assemblies, particularly in trusses, the single bolt goes through both sides of the connected sections, making the connected sheets on each side unrestrained. the warping of the unrestrained sheet may reduce the bearing strength of the bolted connection. This research investigates the behavior and strength of bearing failure in bolted connections in cold-formed steel trusses. Tensile tests were conducted on trusses connections with various material thicknesses. It was found that the AISI S100 works well for thick connections but provides unconservative predictions for thin materials. Based on the experimental results, a modified bearing strength method is proposed for calculating the bearing strength of bolted truss connections. the proposed method can be used for any cold-formed steel connections with unrestrained sheet.
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Corner, Sebastien Marc William. "Screw-Fastened Cold-Formed Steel-to-Steel Shear Connection Behavior and Models." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/78073.
Full textAbstract:
This research introduces a proposed model for predicting tilting angle and limit states of single-fastened cold-formed steel-to-steel shear connections. Predictions are validated through an experimental study considering ply configuration and a single Hex #10 -washer head fastener, centered in a 102 mm by 102 mm three boundary window. The fastener tilting angle is captured using an automated, optical non-contact measurement procedure. The results are used to identify cold-formed steel shear connection deformation as load progresses, including tilting, bearing, and combined tilting bearing at the plies and thread tension, shear and bearing fastener failure. Results shows that fastener tilting plays a kinematic affect for the connection. Fastener tilting is predicted in function of ply thickness and fastener pitch. Local ply bending deformation is reported to be the main deformation of the connection during fastener tilting. While fastener bending and shear failure occurred if the fastener does not tilt.Master of Science
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Qiu, Pei. "Stress-strain behaviour of cold-worded materials in cold-formed stainless steel sections." Thesis, University of Macau, 2011. http://umaclib3.umac.mo/record=b2493011.
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Padilla-Llano, David Alberto. "A Framework for Cyclic Simulation of Thin-Walled Cold-Formed Steel Members in Structural Systems." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/52904.
Full textAbstract:
The objective of this research is to create a computationally efficient seismic analysis framework for cold-formed steel (CFS) framed-buildings supported by hysteretic nonlinear models for CFS members and screw-fastened connections. Design of CFS structures subjected to lateral seismic forces traditionally relies on the strength of subassemblies subjected to lateral loading of systems, such as strapped/sheathed shear walls and diaphragms, to provide adequate protection against collapse. Enabling performance-based seismic design of CFS buildings requires computationally efficient and accurate modeling tools that predict the nonlinear cyclic behavior of CFS buildings, the individual CFS components and connections. Such models should capture the energy dissipation and damage due to buckling and cross-sectional deformations in thin-walled CFS components subjected to cyclic loads such as those induced by earthquakes. Likewise, models for screw-fastened CFS connections should capture the energy dissipation and damage due to tilting, bearing, or screw shear when subjected to cyclic loading.
In this dissertation, an analysis framework for CFS structures that captures the nonlinear cyclic behavior of critical components including axial members, flexural members, and screw fastened connections is presented. A modeling approach to simulate thin-walled behavior in CFS members is introduced where parameters were developed using results from an experimental program that investigated the cyclic behavior and energy dissipation in CFS axial members and flexural members. Energy dissipation and cyclic behavior of CFS members were characterized for members experiencing global, distortional and local buckling. Cyclic behavior and energy dissipation in thin steel plates and members was further investigated through finite element analysis in ABAQUS to provide a strategy for modeling steel columns cyclic behavior including local buckling. Model parameters were developed as generalized functions of the hysteretic energy dissipated and slenderness. The capabilities of the analysis framework are demonstrated through simulations of CFS wood sheathed shear wall cyclic responses validated with experimental results from full scale shear wall tests.Ph. D.
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Bell, David J. "Development of a new cold-formed steel roof truss system." Thesis, Queensland University of Technology, 1997. https://eprints.qut.edu.au/36009/1/36009_Bell_1997.pdf.
Full textAbstract:
This thesis reports on a research and development project which was aimed at
developing a new cold-formed steel roof truss system for Textor Metal Industries Pty
Ltd under a National Teaching Company Scheme. It presents details of analysis,
design, and testing methods used in this project and their results. This Master of
Engineering Degree research thesis was undertaken part-time during the project
duration of two years, and includes in part some research details which are
confidential.
The new cold-formed steel roof truss system was designed for non-cyclonic
permissible design winds of 33 mis and 41 mis. The system was developed for a
maximum span of 12m, and a roof pitch of 20°-25° for a concrete tile roof, and 15°-
250 for a metal sheet roof Both the web and chord members are open thin-walled
sections made from 0.8 mm - 1.0 mm G550 Zinc/Alume coated steel, and they were
connected by a new fastening technology known as clinching. The web members were
plain channel stud sections and the chord members were a new stiffened top plate
section.
In order to obtain accurate strength capacities of the thin-walled sections a rigorous
material and geometric non-linear finite element analysis (FEA) was conducted on the
plain channel stud web members undergoing local buckling using the Nastran package
in combination with the elastic finite strip method Contour software. The method was
verified by stub column tests, and considered several material grades and thicknesses.
The FEA results of section capacity were compared with the predictions of the coldformed
steel structures code AS 153 8 for small member lengths (ie approximating
section capacity). The sections demonstrated the significant post-buckling behaviour
expected of these thin-walled open sections. The comparisons of the FEA results with
AS1538 predictions gave unexpected results. For some cases the FEA result was
higher than the AS1538 result, but for others the AS1538 result was higher. It was clear that the difference between the FEA and AS 153 8 results was not consistent, so
the new roof truss system members were designed using AS1538 with an effective
length departure of 0.7L.
AS 1170 .2 Section 3 was used for the determination of wind loads in preference to
AS4055. AS4055 was found to determine wind loads substantially less than
AS 1170.2 Section 3 due to the adoption of a revised risk philosophy which is
concerned with loss to the overall community rather than loss to individual structures.
This was not accepted for this research. Wind parallel to the ridge plus dead load was
the critical load combination for both strength and serviceability design of the trusses.
The trusses were modelled with fixed web member ends and pinned truss supports
using a plane frame analysis program (SpaceGASS). Design actions from this analysis
and strength capacities from AS1538 (including the 0.7L effective length departure)
were used to design the thickness and grade of material required for the plain channel
stud section web members and the stiffened top plate chord sections.
The member connections of the new roof truss system were clinch fasteners
developed by Tox Systems Pty Ltd. A single shear test program of 685 samples was
conducted to determine the behaviour and capacity of these fasteners. Several
multiple fastener tests were also conducted. Design strength results from the test
program were used in the design of the clinch connections of the new roof truss
system.
A series of five full scale roof truss tests were conducted on an 8m span truss with a
metal sheet roof and a 22. 5° roof pitch to validate the analysis and design assumptions
used in the development of the new truss system. The single and three truss tests
investigated the ultimate and serviceability behaviour of the trusses and the system
effect of multiple trusses due to the presence of roof and ceiling components. A
pneumatic loading system was used to simulate the critical wind load combination of
wind parallel to the ridge and dead load. Both downward pressure wind and upward
suction were simulated, but the upward suction wind case was taken to failure as this
was critical. The test program verified the design and analysis assumptions used in this research
and demonstrated the capacity of the new roof truss system to sustain the design
loads. A comparison of alternative analysis assumptions was performed and showed
that modelling the truss with pinned web member ends and/or pin/roller truss supports
gave predictions which were not in agreement with the test results. The assumptions
of fixed web member ends and pinned truss supports agreed well with the test results,
and hence validated these assumptions used in the design of the trusses.
The trusses in the new roof truss system were designed using the results of the
analysis in combination with the member design in accordance with AS1538
(including the O. 7L effective length departure) and the fastener design in accordance
with the test program. The full scale testing program confirmed that this analysis and
design method was suitable for the trusses. The test truss performed adequately under
both ultimate and serviceability loads. Comparison of test results with analysis and
design showed that the member failure loads were in good agreement with
predictions, and that the mode of failure of the members was also in good agreement
with the predictions. On this basis the same process of analysis and design was used
for the other trusses.
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Young, B. (Ben). "The behaviour and design of cold-formed channel columns." Thesis, Faculty of Engineering, 1997. http://hdl.handle.net/2123/13673.
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Soltani, Maryam. "Image-based analysis of steel sheathed cold-formed steel shear wall buckling behavior." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Find full textAbstract:
The high lateral force resisting feature of the cold-formed steel structure, make it an attractive design choice in seismic zones. The shear strength of these systems controls by two critical factors, the characteristic of the sheathed and the sheathing-to-frame connections. There are many challenges associated with testing different configurations of these thin-wall structures (size, layout, sheathed material). Despite the huge growth of such constructions, the design procedure and the numerical calculation developed by the American Iron and Steel Institute provision AISI S240 (2015) and AISI S400 (2015), didn’t provide a proper standard for the various possible design of the CFS shear walls. This thesis proposes a study aiming to expose the gap across the theory to the practical issue by comparing the equation-based analysis and the image-based analysis of the shear strength of the shear walls.
Two large-scale CFS shear walls infilled with gravity wall were tested under the quasi-static reversed cyclic protocol at the laboratory of the University of California San Diego. These innovative specimens were built with the thicker framing members than the listed ones in the AISI standard and assembled in the specific framing layout. The sheathing-to-frame connections and sheathing parameters like screw spacing, screw size, and thickness of the sheet was the same in both walls.
The shear strength of these walls computed through the effective Strip width method in the provisions of the AISI S400 (2015) by selecting the minimum value between the shear capacity of the connections which bar the shear force in the tension field and the shear strength of the sheathed. Surprisingly the calculated result was one-third of the test results.
This experiment shows how imperfect is the provided equation-based shear strength method by the AISI standard design for CFS Structures.
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Clayton, Scott. "Repetitive member factor study for cold-formed steel framing systems." Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4199.
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Uygar, Celaletdin. "Seismic Design Of Cold Formed Steel Structures In Residential Applications." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607294/index.pdf.
Full textAbstract:
iv
ABSTRACT
SEISMIC DESIGN OF COLD FORMED STEEL STRUCTURES IN
RESIDENTIAL APPLICATIONS
Uygar, Celaletdin
M.Sc., Department of Civil Engineering
Supervisor: Prof. Dr. Çetin Yilmaz May 2005, 82 pages In this study, lateral load bearing capacities of cold formed steel framed wall panels are investigated. For this purpose lateral load bearing alternatives are analyzed numerically by computer models and results are compared with already done experimental studies and approved codes. In residential cold formed steel construction, walls are generally covered with cladding material like oriented strand board (OSB) or plywood on the exterior wall surface and these sheathed light gauge steel walls behave as shear walls with significant capacity. Oriented strand board is used in analytical models since OSB claddings are most commonly used in residential applications. The strength of shear walls depends on different parameters like screw spacing, strength of sheathing, size of fasteners used and aspect ratio. SAP2000 software is used for structural analysis of walls and joint force outputs are collected by Microsoft Excel. The yield strength of shear walls at which first screw connection reaches its shear capacity is calculated and load carrying capacity per meter length is found. The nonlinear analysis is also done by modeling the screw connections between OSB and frame as non-linear link and the nominal shear capacities of walls are calculated for different screw spacing combinations. The results are consistent with the values in shear wall design Guide and International Building Code 2003. The other lateral load bearing method is flat strap X-bracing on wall surfaces. Various parameters like wall frame section thickness, flat strap area, aspect ratio and bracing number are investigated and results are evaluated. The shear walls in which X-bracing and OSB sheathing used together are also analyzed and the results are compared with separate analyses.
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Comeau, Gilles. "Inelastic performance of welded cold-formed steel strap braced walls." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21917.
Full textAbstract:
As cold-formed steel construction grows in North America the void in our building codes must be filled. The NBCC and the CSA S136 Standard currently have no seismic provisions for cold-formed steel construction. Recently, the AISI has made available an updated version of AISI S-213 which includes adaptations for use with Canadian codes. This standard gives guidance on the design and construction of cold-formed steel systems to be used for lateral load resistance and prescribes the use of a capacity approach for seismic design. Seismic force modification factors to be used in conjunction with the NBCC are recommended for two CBF categories; one for limited ductility (Rd = 2.0, Ro = 1.3), examined herein, and one for conventional construction (Rd = 1.25, Ro = 1.3). A building height limit of 20m for the limited ductility system is also recommended. The main objective of this research was the verification of the capacity based design approach, the Rd and Ro values and the building height limit as found in AISI S-213 for limited ductility CBFs. In order to achieve this, the lateral load carrying behaviour of weld-connected cold-formed steel strap braced walls was examined by means of laboratory testing (30 wall specimens). The wall aspect ratio was varied from 1:1 to 1:4 to look at its effect on stiffness and overall performance. Each of the wall specimens was tested using both a monotonic and the CUREE reversed cyclic protocols. Further to these laboratory experiments, non-linear dynamic time history analysis of a multi-storey structure, designed using the Canadian specific AISI S-213 provisions and the NBCC, was carried out. ATC-63, a newly available method for determining the validity of R values, was used to check the AISI S-213 design parameters. Input earthquake records (both synthetic and recorded) were scaled to the UHS for Vancouver, site class C. Walls with aspect ratios of 1:1 and 1:2 showed the ability to sustain lateral loading well into the inelasticLa croissance des constructions en structure d'acier laminé à froid dans l'Amérique du Nord nécessite le colmatage des carences pertinentes dans les codes nationaux du bâtiment. En effet, le Code National du Bâtiment du Canada (CNB) et la norme CSA S136 de l'Association Canadienne de Normalisation ne contiennent aucune directive portant sur la conception de structures en acier laminé à froid sous les charges sismiques. Récemment, l'American Iron and Steel Institute (AISI) a publié une mise-à-jour de la norme Américaine AISI S-213 accommodant des ajustements aux codes Canadien. Cette norme comprend des recommandations visant la conception et la construction de structures en acier laminé à froid pour résister des charges latérales, et exige l'adoption d'une approche de conception sismique basée sur la capacité de la structure. Des facteurs de modification de force, utilisés en concordance avec le CNB, sont prescrits pour deux catégories de cadres à contreventement concentriques (CC): la première catégorie, traitée ci-dessous, est liée à un système de ductilité limitée (Rd = 2.0, Ro = 1.3), alors que la deuxième est relative à la construction traditionnelle (Rd = 1.25, Ro = 1.3). En plus, la hauteur des systèmes à ductilité limitée est plafonnée à 20 mètres. L'objectif principal de la présente recherche est la vérification des méthodes de conception basées sur la capacité du système, les valeurs de Rd et de Ro, et la limite des hauteurs des bâtiments comme proposées par la norme AISI S-213 pour un système à ductilité limitée. Afin de viser ce but, le comportement de 30 murs porteurs assujettis aux charges latérales est testé au laboratoire. Le rapport proportionnel des murs testés est varié entre 1 : 1 et 1 : 4 pour examiner son effet sur la rigidité et le comportement global des murs sous les charges d'essais. Chacune des murs est testée en utilisant un protocole de chargement monotone et le
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Joseph, P. V. "The compressive behaviour of thin-walled cold-formed steel columns." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382225.
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Davies, Russell John. "The behaviour of press-joining in cold-formed steel structures." Thesis, University of Edinburgh, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534541.
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Sabbagh, Alireza Bagheri. "Cold-formed steel elements for earthquake resistant moment frame buildings." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548557.
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Liu, Qiang. "Structural analysis and design of cold formed steel sigma purlins." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3364/.
Full textAbstract:
Cold formed steel (CFS) sigma sections are commonly used as purlins in the construction of modern industrial and residential buildings due to their excellent strength-to-weight ratio. This thesis reports investigations on the structural behaviour of CFS sigma purlins in three different parts of modern roof systems. In the first investigation, the pre-buckling, buckling, post-buckling and post-failure behaviour of continuous CFS sigma purlins near internal supports was studied by experimental and numerical methods. In the second investigation, the moment-rotation response as well as the moment resistance of the sleeve connection of sigma purlins was studied by laboratory tests. Engineering models were developed to predict the behaviour of this connection and a good correlation was observed with the experimental data. In the third investigation, the flexural stiffness and moment resistance of CFS sigma purlins fastened to roof sheeting with large screw spacing was studied experimentally. The purlin-sheeting assemblies were subjected to both downward and uplift loadings, from which different behavioural aspects such as flexural stiffness, failure modes and ultimate load were examined. Test results are utilized to develop design proposals for sigma purlins that codes or standards have not yet covered.
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Monroy, Barbara L. "Deflection gap study for cold-formed steel curtain wall systems." Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2350.
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Setiyono, Ir Harkali. "Web crippling of cold-formed plain channel steel section beams." Thesis, University of Strathclyde, 1994. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27069.
Full textAbstract:
The web crippling strength of cold-formed plain channel steel section beams was investigated theoretically and experimentally in this research program. The web crippling strength in this thesis is termed the ultimate web crippling load and this was theoretically analysed using two different design specifications and a plastic mechanism approach. The two design specifications used in this research program were BS 5950 Part 5:1987 and European Recommendations For The Design of Light Gauge Steel Members, 1987. In the plastic mechanism approach, a plastic mechanism model of web crippling failure was developed and analysed using a method of yield line analysis. This approach has resulted in analytical expressions and these are specially used to analyse the ultimate web crippling load of the plain channel section beams subjected to combined actions of web crippling and bending. Besides the theoretical investigations, experimental investigations were also carried out for many plain channel section beam specimens of various dimensions. In the experimental investigations, test loads applied to the specimens were varied according to the loading conditions specified by AISI 1986 and they were transfered onto the specimens through various load bearing lengths. The experimental results were used to study the influence of various factors on the ultimate web crippling loads and to verify the theoretical results. The accuracy of theoretical results was statistically analysed and their deviations from the experimental results were limited within the acceptable scatter valus ± 20%. Some examples of the web crippling behaviour of the specimens characterized by their experimental load-deflection curves were also presented and, especially for the specimens under combined actions of web crippling and bending, their experimental load-deflection curves were compared to the theoretical collapse curves obtained from the plastic mechanism approach. Finally, the results of the experiments and the verification of each theory used in this research program are discussed and concluded in the last three chapters of this thesis. experiments a nd the verification of each theory used in this research program are discussed and concluded in the last three chapters of this thesis.
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Mahenthirarasa, Rokilan. "Cold-formed steel compression members exposed to extreme temperature environments." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/226125/1/Rokilan_Mahenthirarasa_Thesis.pdf.
Full textAbstract:
This thesis investigated the behaviour of cold-formed steel compression members under extreme temperature environments using experimental and numerical studies. It proposed both new and improved design models for (1) the elevated and sub-zero temperature mechanical properties of cold-formed steels and (2) the compression capacities of cold-formed steel members exposed to uniform and non-uniform elevated temperatures and uniform sub-zero temperatures. The proposed design models are likely to be adopted by the Australian and American cold-formed steel structures standards, while the new knowledge will enable increased applications of cold-formed steel members in the building industry.
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Yong, Pei Ming. "Collapse Behaviour of Cold-Formed Steel Structure at Elevated Temperatures." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/75245.
Full textAbstract:
This thesis describes a full-scale fire test and finite-element (FE) modelling carried out on a cold-formed steel structure. The structure was collapsed with an inwards asymmetrical collapse mechanism. The FE model was validated against the full-scale fire test results where the comparison shows that the FE results were in good correlation with the full-scale fire test results. The results presented in this thesis can contribute to practical design guidance for fire safety engineering.
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Darcy, Greg. "Structural behaviour of an innovative cold-formed steel building system." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16589/1/Greg_Darcy_Thesis.pdf.
Full textAbstract:
Cold-formed steel structures have been in service for many years and are used as shelters for both domestic and industrial purposes. To produce an economical product, manufacturers have typically based their designs on the simple portal frame concept. As there is almost a direct relationship between overall cost and the weight of steel in a portal frame structure, it is of great importance to provide a structure with the minimum amount of steel whilst providing structural adequacy.
Portal frame sheds have been refined continuously for many years, with only minimal amounts of savings in steel. Therefore, to provide even greater savings in steel, an innovative building system is required. Modern Garages Australia (MGA) is one of the leading cold-formed steel shed manufacturers in Queensland. MGA has recently developed such an innovative building system that has significant economic savings when compared with portal frame structures.
The MGA building system has two key differences to that of the conventional portal frame system. These differences are that the MGA system has no conventional frames or framing system, and it has no purlins or girts. This results in the MGA system being completely fabricated from thin cladding, which significantly reduces the quantity of steel. However, the key problem with this building system is that the load paths and structural behaviour are unknown, and therefore the structure cannot be analysed using conventional methods. Therefore, the objectives of this research were to first investigate the structural behaviour of this new building system and its adequacy for an ultimate design wind speed of 41 m/s using full scale testing. The next objectives were to use finite element analysis to optimise the original MGA building system so that it is adequate for an ultimate design wind speed of 41 m/s, and to develop a new improved cold-formed steel building system that has greater structural efficiency than the original MGA building system.
This thesis presents the details of the innovative MGA building system, full scale test setup, testing program, finite element analysis of the MGA building system and the results. Details and results from the optimisation of the MGA building system, and the development of a new improved cold-formed steel building system are also presented. The full scale experimental investigation considered the required loadings of cross wind, longitudinal wind and live load test cases and simulated them on the test structure accurately using an innovative load simulation system. The wind loads were calculated for a 41 m/s ultimate design wind speed. Full scale test program included both non-destructive and destructive tests.
The finite element analyses contained in this thesis have considered cross wind, longitudinal wind and live load cases, as well as the destructive load case of the MGA building system. A number of different model types were created and their results were compared with the experimental results. In general, two main model types were created. The first type consisted of a 'strip' of the MGA building system (Strip model) and the second modelled the full structure (Full model). Both of these model types were further divided into models which contained no contact surfaces and those which contained contact surfaces to simulate the interfaces between the various components such as the brackets and cladding.
The experimental test results showed that the MGA test structure is not suitable for an ultimate design wind speed of 41 m/s. This conclusion is a result of a number of observed failures that occurred during the extensive testing program. These failures included local buckling, crushing failures, and distortional buckling of the cladding panels. Extremely large deflections were also observed. It was calculated that for the MGA building system to be adequate for the design wind speed of 41 m/s, a cladding thickness of 0.8 mm was required. This also agreed well with the finite element analysis results which concluded that a cladding thickness of 0.8 mm was required.
In order to avoid the increased use of steel in the building system, a new improved cold-formed steel building system was developed and its details are provided in this thesis. A finite element model of this new improved cold-formed steel building system was created and the results showed that the new building system was able to achieve a load step equivalent to an ultimate design wind speed of 50.4 m/s and was approximately 250% stiffer than the original MGA building system, without any increase in the overall weight of the building system. It is recommended that this new improved cold-formed steel building system be further developed with the aid of finite element modelling and be tested using a similar full scale testing program that was used for the original MGA building system.
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Darcy, Greg. "Structural behaviour of an innovative cold-formed steel building system." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16589/.
Full textAbstract:
Cold-formed steel structures have been in service for many years and are used as shelters for both domestic and industrial purposes. To produce an economical product, manufacturers have typically based their designs on the simple portal frame concept. As there is almost a direct relationship between overall cost and the weight of steel in a portal frame structure, it is of great importance to provide a structure with the minimum amount of steel whilst providing structural adequacy. Portal frame sheds have been refined continuously for many years, with only minimal amounts of savings in steel. Therefore, to provide even greater savings in steel, an innovative building system is required. Modern Garages Australia (MGA) is one of the leading cold-formed steel shed manufacturers in Queensland. MGA has recently developed such an innovative building system that has significant economic savings when compared with portal frame structures. The MGA building system has two key differences to that of the conventional portal frame system. These differences are that the MGA system has no conventional frames or framing system, and it has no purlins or girts. This results in the MGA system being completely fabricated from thin cladding, which significantly reduces the quantity of steel. However, the key problem with this building system is that the load paths and structural behaviour are unknown, and therefore the structure cannot be analysed using conventional methods. Therefore, the objectives of this research were to first investigate the structural behaviour of this new building system and its adequacy for an ultimate design wind speed of 41 m/s using full scale testing. The next objectives were to use finite element analysis to optimise the original MGA building system so that it is adequate for an ultimate design wind speed of 41 m/s, and to develop a new improved cold-formed steel building system that has greater structural efficiency than the original MGA building system. This thesis presents the details of the innovative MGA building system, full scale test setup, testing program, finite element analysis of the MGA building system and the results. Details and results from the optimisation of the MGA building system, and the development of a new improved cold-formed steel building system are also presented. The full scale experimental investigation considered the required loadings of cross wind, longitudinal wind and live load test cases and simulated them on the test structure accurately using an innovative load simulation system. The wind loads were calculated for a 41 m/s ultimate design wind speed. Full scale test program included both non-destructive and destructive tests. The finite element analyses contained in this thesis have considered cross wind, longitudinal wind and live load cases, as well as the destructive load case of the MGA building system. A number of different model types were created and their results were compared with the experimental results. In general, two main model types were created. The first type consisted of a 'strip' of the MGA building system (Strip model) and the second modelled the full structure (Full model). Both of these model types were further divided into models which contained no contact surfaces and those which contained contact surfaces to simulate the interfaces between the various components such as the brackets and cladding. The experimental test results showed that the MGA test structure is not suitable for an ultimate design wind speed of 41 m/s. This conclusion is a result of a number of observed failures that occurred during the extensive testing program. These failures included local buckling, crushing failures, and distortional buckling of the cladding panels. Extremely large deflections were also observed. It was calculated that for the MGA building system to be adequate for the design wind speed of 41 m/s, a cladding thickness of 0.8 mm was required. This also agreed well with the finite element analysis results which concluded that a cladding thickness of 0.8 mm was required. In order to avoid the increased use of steel in the building system, a new improved cold-formed steel building system was developed and its details are provided in this thesis. A finite element model of this new improved cold-formed steel building system was created and the results showed that the new building system was able to achieve a load step equivalent to an ultimate design wind speed of 50.4 m/s and was approximately 250% stiffer than the original MGA building system, without any increase in the overall weight of the building system. It is recommended that this new improved cold-formed steel building system be further developed with the aid of finite element modelling and be tested using a similar full scale testing program that was used for the original MGA building system.
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Balasubramaniam, Janarthanan. "Structural behaviour and design of cold-formed steel floor systems." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/112811/1/Janarthanan_Balasubramaniam_Thesis.pdf.
Full textAbstract:
This thesis investigated the complex structural behaviour of unlipped channel section bearers used in cold-formed steel floor systems. Using both experimental and numerical studies, web critical failure modes of a range of unlipped channels fastened to their supports were first investigated, followed by the failures caused by combined actions of web crippling, bending and torsion with increasing spans and the effects of connection stiffness on the behaviour. New design methods were then developed to predict the ultimate capacities of unlipped channels under isolated and combined actions. This research will thus enhance the safety and cost-efficiency of cold-formed steel floor systems.
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Rinchen. "Long-span cold-formed steel single C-section portal frames." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18882.
Full textAbstract:
This thesis presents a comprehensive study of long-span cold-formed steel single C-section portal frames. The study includes the formulation of a nonlinear beam finite element for thin-walled sections, a series of full-scale frame tests and component tests, finite element modelling and advanced analysis followed by the formulation of design guidelines. The study was aimed at exploring the structural behaviour through experiment and numerical analysis towards developing provisions for the design of cold-formed steel portal frames using Advanced Analysis. A nonlinear thin-walled beam element for general open cross-sections was formulated, incorporating warping effect and non-coincident location of the shear centre and the centroid. It was successfully implemented in the geometric nonlinear analysis framework of the OpenSees finite element software. Towards investigating the behaviour and determining the ultimate strength, six full-scale tests on cold-formed steel single C-section portal frames were conducted. Separate tests were performed on frame connections, point-fastener connections and coupons to obtain the material parameters required for numerical modelling. Advanced shell finite element models of the full-scale frames and frame connections were created and validated against experimental results. The bolts and screws used for the connections between components were represented by point-based deformable fasteners. The force-deformation characteristics of the deformable fasteners were incorporated and successfully implemented in the Advanced Analysis. The strength of cold-formed steel single C-section portal frames determined by the Direct Strength Method and the Direct Design Method were compared. To account for inherent uncertainties in the strength of CFS portal frames, system resistance factors were derived. It was concluded that the Direct Design Method using Advanced Analysis is the likely future method for the design of cold-formed steel portal frames.
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Jefferson, David. "The elasto-plastic localised buckling behaviour of cold-formed sections." Thesis, Oxford Brookes University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328301.
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