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1
Peacock, Simon. « Mechanical properties of rotary forged sintered steel compacts ». Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319953.
Texte intégral
2
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/.
Texte intégralRésumé :
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.
3
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.
Texte intégralRésumé :
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
4
Jobe, Jeffrey M. « Blast resistant forced entrty [sic] steel stud wall design ». Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5850.
Texte intégralRésumé :
Thesis (M.S.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (January 23, 2007) Includes bibliographical references.
5
Yanagi, Noritsugu. « Analytical Model of Cold-formed Steel Framed Shear Wall with Steel Sheet and Wood-based Sheathing ». Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271920/.
Texte intégralRésumé :
The cold-formed steel framed shear walls with steel sheets and wood-based sheathing are both code approved lateral force resisting system in light-framed construction. In the United States, the current design approach for cold-formed steel shear walls is capacity-based and developed from full-scale tests. The available design provisions provide nominal shear strength for only limited wall configurations. This research focused on the development of analytical models of cold-formed steel framed shear walls with steel sheet and wood-based sheathing to predict the nominal shear strength of the walls at their ultimate capacity level. Effective strip model was developed to predict the nominal shear strength of cold-formed steel framed steel sheet shear walls. The proposed design approach is based on a tension field action of the sheathing, shear capacity of sheathing-to-framing fastener connections, fastener spacing, wall aspect ratio, and material properties. A total of 142 full scale test data was used to verify the proposed design method and the supporting design equations. The proposed design approach shows consistent agreement with the test results and the AISI published nominal strength values. Simplified nominal strength model was developed to predict the nominal shear strength of cold-formed steel framed wood-based panel shear walls. The nominal shear strength is determined based on the shear capacity of individual sheathing-to-framing connections, wall height, and locations of sheathing-to-framing fasteners. The proposed design approach shows a good agreement with 179 full scale shear wall test data. This analytical method requires some efforts in testing of sheathing-to-framing connections to determine their ultimate shear capacity. However, if appropriate sheathing-to-framing connection capacities are provided, the proposed design method provides designers with an analytical tool to determine the nominal strength of the shear walls without conducting full-scale tests.
6
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/.
Texte intégralRésumé :
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.
7
Francka, Ryan Michael. « Screw connections subject to tension pull-out and shear forces ». Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Francka_09007dcc8070fae3.pdf.
Texte intégralRésumé :
Thesis (M.S.)--Missouri University of Science and Technology, 2009.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 23, 2009) Includes bibliographical references (p. 52).
8
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.
Texte intégralRésumé :
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.
9
Lagerqvist, Ove. « Patch loading : resistance of steel girders subjected to concentrated forces ». Doctoral thesis, Luleå, 1995. http://epubl.luth.se/avslutade/0348-8373/159/index.html.
Texte intégral
10
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/.
Texte intégralRésumé :
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.
11
Raoof, Mohammed. « Interwire contact forces and the static, hysteretic and fatigue properties of multi-layer structural strands ». Thesis, University of London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339423.
Texte intégral
12
Niu, Shuang. « Interaction Buckling of Cold-Formed Stainless Steel Beams ». Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11541.
Texte intégralRésumé :
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.
13
Dongsheng, Han, et rising_sun_han@hotmail com. « Robust Control for Offshore Steel Jacket Platforms under Wave-Induced Forces ». Central Queensland University. School of Computing Sciences, 2008. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20080717.104813.
Texte intégralRésumé :
This thesis is concerned with robust control of an offshore steel jacket platform
subject to nonlinear wave-induced forces. Since time delay and uncertainty are
inevitably encountered for an offshore structure and their existence may induce instability, oscillation and poor performance, it is very significant to study on how the
delay and uncertainty affect the offshore structure. In this thesis, a memory robust
control strategy is, for the first time, proposed to reduce the internal oscillations
of the offshore structure under wave-induced forces, so as to ensure the safety and
comfort of the offshore structure.
Firstly, when the system's states are adopted as feedback, memory state feedback
controllers are introduced for the offshore structure. By using Lyapunov-Krasovskii
stability theory, some delay-dependent stability criteria have been established, based
on which, and by combining with some linearization techniques, memory state feedback controllers are designed to control the offshore structure. The simulation results show that such controllers can effectively reduce the internal oscillations of the
offshore structure subject to nonlinear wave-induced forces and uncertainties. On
the other hand, a new Lyapunov-Krasovskii functional is introduced to derive a less
conservative delay-dependent stability criterion. When this criterion is applied to
the offshore structure, an improved memory state feedback controller with a small
gain is obtained to control the system more effectively, which is sufficiently shown
by the simulation.
Secondly, when the system's outputs are adopted as feedback, memory dynamic
output feedback controllers are considered for the offshore structure. By employing
a projection theorem and a cone complementary linearization approach, memory
dynamic output feedback controllers are derived by solving some nonlinear minimization problem subject to some linear matrix inequalities. The simulation results
show that the internal oscillations of the offshore structure subject to nonlinear
wave-induced forces are well attenuated.
Finally, robust H control is fully investigated for the offshore structure. By employing Lyapunov-Krasovskii stability theory, some delay-dependent bounded real
lemmas have been obtained, under which, via a memory state feedback controller or
a dynamic output feedback controller, the resulting closed-loop system is not only
asymptotically stable but also with a prescribed disturbance attenuation level. The
simulation results illustrate the validity of the proposed method.
14
Wang, Bin. « Shape Optimisation of Cold-Formed Steel Cross-Sectional Profiles With or Without Manufacturing and Assembly Constraints ». Thesis, Griffith University, 2017. http://hdl.handle.net/10072/366338.
Texte intégralRésumé :
Cold-formed steel (CFS) members are extensively used in construction industry as the primary and/or secondary load-bearing structural systems. CFS products can be mass manufactured at room temperature and rapidly installed on-site. Compared to the traditional hot-rolled steel and concrete structures, CFS structures have a high capacity-to-weight ratio and present real benefits and opportunities for architects and engineers to achieve a greener structural solution. CFS products are typically formed by bending steel sheets or strips (up to 6 mm thick) using a number of rollers (roll-forming) or die blocks (brake-pressing). The current manufacturing process allows the CFS products to be shaped into any desired (infinite) cross-sectional shapes with consecutive manufacturing bends. However, most of the commonly used CFS cross-sectional shapes are mainly restricted to “Cee”, “Zee” and “Sigma”. To address the issue of local instabilities, the conventional cross-sections have been improved by the inclusion of web and/or flange stiffeners and the optimisation of their dimensions (height, width and thickness). Despite these advances in cross-sectional design, little research has been done to discover new cross-sectional shapes to achieve an optimum solution. A revolutionary innovation in the crosssectional shape of the CFS products is therefore being pushed forward in this research.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
15
Sears, Jeffrey M. « Development of Prediction Methods for the Lateral Anchorage Requirements in Metal Building Roof Systems ». Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32382.
Texte intégralRésumé :
Metal building roof systems with C- or Z-section purlins require restraint to resist lateral forces developed within the roof system under gravity loads. The currently available procedures for predicting these forces have been shown to be inaccurate for sloped roofs and difficult to apply to roof configurations with multiple points of anchorage. A new method has been developed that builds on the previous research and accurately addresses roof slope as well as the use of multiple anchorage devices of finite stiffness. The development of this method relied on a stiffness model, similar to that used by previous researchers, which was updated and calibrated to the results of recently completed tests. The calculation procedure explicitly addresses the location and stiffness of anchorage devices as well as the inherent stiffness of the purlin system to accurately distribute the anchorage forces.Master of Science
16
Döhnert, Sylvia 1970. « Mediating regional development : how metalworking firms forged lasting linkages with steel in Ciudad, Guayana, Venezuela ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/29314.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, February 2003.Includes bibliographical references (v. 2, leaves 263-275).
Ever since the late 1950s, planners have lured large firms to lagging regions with the expectation that they will trigger local industrial activity. According to the literatures on unbalanced growth, growth poles, foreign direct investment, and global commodity chains, large firms can dynamize lagging economies by creating a market for inputs, which then stimulates and fortifies local suppliers. Yet in practice, many national and regional development efforts centered on attracting large firms have not elicited this hoped for, backward linkage effect. This study researches why large firms arriving to lagging regions seldom induce local suppliers, and how they can. Existing studies relate linkage behavior to firm-specific or industry-specific variables. This research differs in looking at the process through which large firms develop links to local suppliers. Specifically, this study traces the evolution of backward linkages in Ciudad Guayana, Venezuela, where more than 100 small and medium metalworking firms developed to supply the large steel firm Siderirgica del Orinoco (SIDOR) with maintenance, parts and equipment. Research of other steel-centered cases in lagging regions reveals that this linkage effect is uncommon. When it happens, local suppliers tend to disappear following their client firm's restructuring. In contrast, Ciudad Guayana's metalworking firms successfully survived SIDOR's 1997 privatization to a foreign multinational, and head regional development efforts there today.
(cont.) Two main findings emerge from this study. First, backward linkages do not occur automatically, for large firms arriving to lagging regions tend to resist local procurement. In Ciudad Guayana, both foreign firms and state-owned enterprises charged with regional development exhibited this resistance towards local suppliers. Second, local suppliers can build customer-supplier relations to these large, potential customers despite their initial resistance. To do so, local suppliers must simultaneously address the demand-side and supply-side difficulties that inhibit localized linkages. Local suppliers must convince potential customers to procure locally, and at the same time facilitate local firms' investment in upgrading. This work requires significant collective action, mediation, and embeddedness on the part of local suppliers' business organizations. Luckily, the case of Ciudad Guayana shows how local suppliers may develop these abilities within the process of building backward linkages itself.
by Sylvia Dohnert.
Ph.D.
17
Zhao, Wen-Bin. « Behaviour and design of cold-formed steel hollow flange sections under axial compression ». Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16909/1/Wen-Bin_Zhao_Thesis.pdf.
Texte intégralRésumé :
The use of cold-formed steel structures is increasing rapidly around the world due to the many advances in construction and manufacturing technologies and relevant standards. However, the structural behaviour of these thin-walled steel structures is characterised by a range of buckling modes such as local buckling, distortional buckling or flexural torsional buckling. These buckling problems generally lead to severe reduction and complicated calculations of their member strengths. Therefore it is important to eliminate or delay these buckling problems and simplify the strength calculations of cold-formed steel members.
The Hollow Flange Beam with two triangular hollow flanges, developed by Palmer Tube Mills Pty Ltd in the mid-1990s, has an innovative section that can delay the above buckling problems efficiently. This structural member is considered to combine the advantages of hot-rolled I-sections and conventional cold-formed sections such as C- and Z-sections (Dempsey, 1990). However, this structural product was discontinued in 1997 due to the complicated manufacturing process and the expensive electric resistance welding method associated with severe residual stresses (Doan and Mahendran, 1996). In this thesis, new fastening methods using spot-weld, screw fastener and self-pierced rivet were considered for the triangular Hollow Flange Beams (HFBs) and the new rectangular hollow flange beams (RHFBs). The structural behaviour of these types of members in axial compression was focused in this research project. The objective of this research was to develop suitable design models for the members with triangular and rectangular hollow flanges using new fastening methods so that their behaviour and ultimate strength can be predicted accurately under axial compression.
In the first stage of this research a large number of finite element analyses (FEA) was conducted to study the behaviour of the electric resistance welded, triangular HFBs (ERW-HFBs) under axial compression. Experimental results from previous researchers were used to verify the finite element model and its results. Appropriate design rules based on the current design codes were recommended. Further, a series of finite element models was developed to simulate the corresponding HFBs fastened using lap-welds (called LW-HFBs) and screw fasteners or spot-welds or self-piercing rivets (called S-HFBs). Since the test specimens of LW-HFBs and S-HFBs were unavailable, the finite element results were verified by comparison with the experimental results of ERW-HFB with reasonable agreement.
In the second stage of this research, a total of 51 members with rectangular hollow flanges including the RHFBs made from a single plate and 3PRHFBs made from three plates fastened with spot-welds and screws was tested under axial compression. The finite element models based on the tests were then developed that included the new fasteners, contact simulations, geometric imperfections and residual stresses. The improved finite element models were able to simulate local buckling, yielding, global buckling and local/global buckling interaction failure associated with gap opening as agreed well with the corresponding full-scale experimental results. Extensive parametric studies for the RHFBs made from a single plate and the 3PRHFBs made from three plates were undertaken using finite element analyses. The analytical results were compared with the predictions using the current design rules based on AS 4100, AS/NZS 4600 and the new direct strength method. Appropriate design formulae based on the direct strength method for RHFBs and 3PRHFBs were developed. This thesis has thus enabled the accurate prediction of the behaviour and strength of the new compression members with hollow flanges and paved the way for economical and efficient use of these members in the industry.
18
Zhao, Wen-Bin. « Behaviour and design of cold-formed steel hollow flange sections under axial compression ». Queensland University of Technology, 2006. http://eprints.qut.edu.au/16909/.
Texte intégralRésumé :
The use of cold-formed steel structures is increasing rapidly around the world due to the many advances in construction and manufacturing technologies and relevant standards. However, the structural behaviour of these thin-walled steel structures is characterised by a range of buckling modes such as local buckling, distortional buckling or flexural torsional buckling. These buckling problems generally lead to severe reduction and complicated calculations of their member strengths. Therefore it is important to eliminate or delay these buckling problems and simplify the strength calculations of cold-formed steel members.
The Hollow Flange Beam with two triangular hollow flanges, developed by Palmer Tube Mills Pty Ltd in the mid-1990s, has an innovative section that can delay the above buckling problems efficiently. This structural member is considered to combine the advantages of hot-rolled I-sections and conventional cold-formed sections such as C- and Z-sections (Dempsey, 1990). However, this structural product was discontinued in 1997 due to the complicated manufacturing process and the expensive electric resistance welding method associated with severe residual stresses (Doan and Mahendran, 1996). In this thesis, new fastening methods using spot-weld, screw fastener and self-pierced rivet were considered for the triangular Hollow Flange Beams (HFBs) and the new rectangular hollow flange beams (RHFBs). The structural behaviour of these types of members in axial compression was focused in this research project. The objective of this research was to develop suitable design models for the members with triangular and rectangular hollow flanges using new fastening methods so that their behaviour and ultimate strength can be predicted accurately under axial compression.
In the first stage of this research a large number of finite element analyses (FEA) was conducted to study the behaviour of the electric resistance welded, triangular HFBs (ERW-HFBs) under axial compression. Experimental results from previous researchers were used to verify the finite element model and its results. Appropriate design rules based on the current design codes were recommended. Further, a series of finite element models was developed to simulate the corresponding HFBs fastened using lap-welds (called LW-HFBs) and screw fasteners or spot-welds or self-piercing rivets (called S-HFBs). Since the test specimens of LW-HFBs and S-HFBs were unavailable, the finite element results were verified by comparison with the experimental results of ERW-HFB with reasonable agreement.
In the second stage of this research, a total of 51 members with rectangular hollow flanges including the RHFBs made from a single plate and 3PRHFBs made from three plates fastened with spot-welds and screws was tested under axial compression. The finite element models based on the tests were then developed that included the new fasteners, contact simulations, geometric imperfections and residual stresses. The improved finite element models were able to simulate local buckling, yielding, global buckling and local/global buckling interaction failure associated with gap opening as agreed well with the corresponding full-scale experimental results. Extensive parametric studies for the RHFBs made from a single plate and the 3PRHFBs made from three plates were undertaken using finite element analyses. The analytical results were compared with the predictions using the current design rules based on AS 4100, AS/NZS 4600 and the new direct strength method. Appropriate design formulae based on the direct strength method for RHFBs and 3PRHFBs were developed. This thesis has thus enabled the accurate prediction of the behaviour and strength of the new compression members with hollow flanges and paved the way for economical and efficient use of these members in the industry.
19
Kiew, Kwong Hui. « Evaluation of internal forces in cross frames of multi-stringer steel bridges ». The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1203101264.
Texte intégral
20
Johnson, Adam. « A Study on the System Reliability of Cold-Formed Steel Roof Trusses ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984220/.
Texte intégralRésumé :
This thesis presents a research project aimed at advancing the treatment of cold-formed steel (CFS) structural reliability in roof trusses. Structural design today relies almost exclusively on component-level design, so structural safety is assured by limiting the probability of failure of individual components. Reliability of the entire system is typically not assessed, so in a worst-case scenario the system reliability may be less than the component reliability, or in a best-case scenario the system reliability may be much greater than the component reliability. A roof truss itself, is a subsystem with several possible failure modes that are being studied in this test program. These trusses are constructed of CFS members that nest with one another at the truss nodes and are connected by drilling fasteners through the mated surfaces, as well as having steel sheathing fastened to the top chords for lateral bracing. Presented in this paper is a series of full-scale static tests on single cold-formed steel roof trusses with a unique experimental setup. The test specimens were carefully monitored to address multiple failure modes: buckling of the top chord, buckling of the truss webs, and any connection failures. This research includes the experimental results, the computed system reliability of the trusses as well as their relationship between the components reliability.
21
Huynh, Minh Toan. « Structural Behaviour of Cold-Formed Steel Screwed Connections ». Thesis, The University of Sydney, 2020. https://hdl.handle.net/2123/22098.
Texte intégralRésumé :
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.
22
Ganesan, Karthik. « Resistance Factor for Cold-Formed Steel Compression Members ». Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33694.
Texte intégralRésumé :
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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Chen, Yujie. « Nominal Shear Strength and Seismic Detailing of Cold-formed Steel Shear Walls using Steel Sheet Sheathing ». Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc30444/.
Texte intégralRésumé :
In this research, monotonic and cyclic tests on cold-formed steel shear walls sheathed with steel sheets on one side were conducted to (1) verify the published nominal shear strength for 18-mil and 27-mil steel sheets; and (2) investigate the behavior of 6-ft. wide shear walls with multiple steel sheets. In objective 1: this research confirms the discrepancy existed in the published nominal strength of 27-mil sheets discovered by the previous project and verified the published nominal strength of 18 mil sheet for the wind design in AISI S213. The project also finds disagreement on the nominal strength of 18-mil sheets for seismic design, which is 29.0% higher than the published values. The research investigated 6-ft. wide shear wall with four framing and sheathing configurations. Configuration C, which used detailing, could provide the highest shear strength, compared to Configurations A and B. Meanwhile, the shear strength and stiffness of 2-ft. wide and 4-ft. wide wall can be improved by using the seismic detailing.
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Yousof, Mohamad. « Analytical Model for Lateral Deflection in Cold-formed Steel Framed Shear Walls with Steel Sheathing ». Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700013/.
Texte intégralRésumé :
An analytical model for lateral deflection in cold-formed steel shear walls sheathed with steel is developed in this research. The model is based on the four factors: fastener displacement, steel sheet deformation, and hold-down deformation, which are from the effective strip concept and a complexity factor, which accounts for the additional influential factors not considered in the previous three terms. The model uses design equations based on the actual material and mechanical properties of the shear wall. Furthermore, the model accounts for aggressive and conservative designers by predicting deflection at different shear strength degrees.
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Dara, Martin Luther. « Direct Strength Method for Web Crippling of Cold-formed Steel C and Z Sections Subjected to Interior One Flange Loading and End One Flange Loading ». Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822839/.
Texte intégralRésumé :
The main objective of this research is to extend the “Direct strength method” for determining the web crippling strength of cold-formed steel C and Z sections subjected to End one flange loading and Interior one flange loading conditions. Direct strength method is applied for designing the columns and beams earlier. The existing specifications equation for calculating the web crippling strength of cold-formed steels designed by American Institute of Iron and Steel is very old method and it is based on the extensive experimental investigations conducted at different universities. Calculating the web crippling strength of cold-formed steels using direct strength method is a new technique. In the present research the web crippling strength of cold-formed steels were calculated using Direct Strength Method. The experimental data is collected from the tests that were conducted at different universities. The critical buckling strength of the members were calculated using Abaqus. Microsoft excel is used to generate the equations. The safety and resistance factors for the designed equations were calculated using “Load and resistance factor design” and “Allowable strength design” from North American Cold-Formed Steel Specification, 2012 edition book.
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Rasmussen, Kim J. R. « Stability of thin-walled structural members and systems ». Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/18194.
Texte intégralRésumé :
This DEng thesis consists of 83 articles containing research material on the stability of thin-walled structural members and systems with emphasis on metal structures. Metal structures are used widely in the construction industry. They include structural members and frames made from rolled and fabricated steel, cold-formed steel, stainless steel and aluminium. Common to these products is the desire to minimise the cross-sectional area to reduce weight and cost. Structural cross-sections are therefore thin-walled and prone to buckling, and an overriding consideration in the design of metal structures is to account for buckling in determining the strength of sections, members and frames. Specifically, the thesis is concerned with determining the reduction in buckling capacity and strength of structural members and frames caused by cross-sectional buckling and material softening. The thesis presents research under the headings Stainless Steel Structures - Hollow Sections, covering tubular columns, beams and welded connections; Stainless Steel Structures - Open Sections, addressing the effect of distortional buckling and interaction buckling on the design of stainless steel columns and beams; Analysis of Locally Buckled Members and Frames, describing a theory to determine the buckling loads of locally and/or distortionally buckled members and frames; Behaviour and Design of Members and Sections Composed Solely or Predominantly from Unstiffened Elements, outlining analytical, numerical and experimental research to advance the understanding of the behaviour and design of singly symmetric cross-sections made up entirely or predominantly from plate elements, including angle sections, T-sections and plain channel sections; Cold-formed Steel Structural Systems, describing numerical and experimental investigations of steel storage racks including selective and drive-in racking systems; and System-based Design of Steel Structures, developing a general framework for designing steel structural framing systems by advanced analysis, termed the Direct Design Method. The thesis also highlights the implementation of the research outcomes in national and international specifications for the design of steel, cold-formed steel and stainless steel structures.
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Mologni, Omar. « Cable tensile force monitoring in steep slope forest operations ». Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3426820.
Texte intégralRésumé :
The interest in active sustainable management of mountain forests is increasing around the world. Great effort, in particular, is focusing on the identification of efficient, safe, and sustainable steep slope harvesting solutions adapted to different environmental conditions. The main attention is moving toward winch-assist harvesting systems on trafficable terrain and European designed standing skyline mobile tower yarders on non-trafficable terrain. These cable-supported harvesting solutions have similar safety issues related to the use of tensioned wire ropes and the use of natural anchors. This research focused on the analysis of cable tensile force while operating with these harvesting solutions in ordinary harvesting sites and operational conditions.
First, a state-of-the-art about the steep slope cable-supported harvesting solutions and their main safety issues was completed. A particular focus was dedicated to the significant works on cable tensile force monitoring. Following, field studies were successfully carried out to monitor the cable tensile forces on ordinary logging operations. The survey interested eleven mobile tower yarders, observed on twelve different cable lines in the Italian Alps, and three large integrated-winch forwarders, observed on eight trails in the interior of British Columbia (Canada). A similar approach, based on the integration of tensile force monitoring, video recording of the operations, ground profile analysis, and load measurement/estimation, was applied to both the cable-supported systems. The case studies, the methodological approach used for the data collection and analysis, and the results of the monitoring are presented and reported in detail.
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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.
Texte intégralRésumé :
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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Artman, Jeremy J. « The Design and Development of Lightweight Composite Wall, Roof, and Floor Panels for Rigid Wall Shelter ». Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1157596/.
Texte intégralRésumé :
This thesis presents a research effort aimed at developing a stronger, lighter, and more economic shelter using rigid wall panels. Reported herein is insulation research, wall and roof panel design and testing, floor section modeling and strength calculations, and cost and weight calculations. Beginning stages focus on developing solid wall and roof panels using cold-formed steel corrugated sheathing and members, as well as polyurethane spray foam for insulation. This research includes calculating uniform load density, to determine the overall strength of the panel. The next stage focuses on the flexural strength of the wall and roof panels, as well as finalizing the floor design for the shelter. This includes determining maximum flexural strength required to meet the standards set by the project goal. Direct strength method determined the correct thickness of members to use based on the dimension selected for the design. All Phases incorporated different connection methods, with varied stud spacing, to determine the safest design for the new shelters. Previous research has shown that cold-formed steel corrugated sheathing performs better than thicker flat sheathing of various construction materials, with screw and spot weld connections. Full scale shear wall tests on this type of shear wall system have been conducted, and it was found that the corrugated sheathing had rigid board behavior before it failed in shear buckling in sheathing and sometimes simultaneously in screw connection failures. Another aspect of the research is on the insulation of the wall panels. Research was conducted on many different insulation options for the mobile facilities. Specifically, insulation made of lightweight material, is non-combustible, added rigidity to the structure, and has high thermal properties. Closed cell polyurethane spray foam was selected for full-scale testing in this research. Closed cell polyurethane adds extra rigidity, is lighter than common honeycomb insulation, and has a higher R-value. Several polyurethane foam companies were studied for this research, and promising products were identified. The research focuses on the impacts of the polyurethane foam to the structural performance of the wall panels. Both shear and 4-point bending tests were completed to investigate the strength and behavior of the cold-formed steel framed wall panels with polyurethane foam insulation. Comparing the cost and weight of the current shelter, and the new design is reported herein. The material studies, specimen details, and test results are reported in this thesis.
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Wilkinson, Simon James. « An investigation into the behaviour of steel proprietary support structures ». Thesis, Nottingham Trent University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369256.
Texte intégral
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Ashkanalam, Aida. « Design Method of Cold-Formed Steel Framed Shear Wall Sheathed by Structural Concrete Panel ». Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1609092/.
Texte intégralRésumé :
The objective of this research is developing a new method of design for cold-formed steel framed shear wall sheathed by ¾" thick USG structural panel concrete subfloor using a predictive analytical model and comparing the results obtained from the model with those achieved from real testing to verify the analytical model and predicted lateral load-carrying capacity resulted from that. Moreover, investigating the impact of various screw spacings on shear wall design parameter such as ultimate strength, yield strength, elastic stiffness, ductility ratio and amount of energy dissipation is another purpose of this research.
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Liu, Hanwen. « The slip modulus between cold formed steel and timber sheathing based on fastener spacing increment ». Kansas State University, 2018. http://hdl.handle.net/2097/38826.
Texte intégralRésumé :
Master of ScienceDepartment of Civil Engineering
Hani Melhem
The combination of cold formed steel (CFS) with structural wood panels exhibits a degree of partial composite action behavior. In the current design and construction codes, CFS and wood sheathing systems are considered separate, in a non-composite manner, due to the absence of sufficient supporting experimental and research data. The problem with previous research is the lack of information to fully define the composite action between CFS and wood sheathing. The scope of this study is to check fundamental information provided in previous research. The approach adopted to solve the problem follows previous experimental procedures conducted at Kansas State University. The objective of the research is to determine the slip modulus with various fastener spacing. Additional results obtained in this study are compared to previous research results.
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Rowen, Alexander David. « Structural, Thermal, and Corrosion Properties of a Cold-Formed Steel Rigid Wall Relocatable Shelter ». Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703438/.
Texte intégralRésumé :
A prototype rigid wall relocatable shelter was designed and constructed using cold-formed steel (CFS) construction techniques including shear walls with corrugated sheathings. The design of the shelter was to be mechanically sound with adequate thermal performance and resistance to corrosion. Modeling of structural shear walls was performed using ABAQUS and verified with experimental results. At the project's conclusion, a completed full-scale prototype shelter was constructed.
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Lan, Xing. « Seismic Performance Evaluation of Novel Cold-Formed Steel Framed Shear Walls Sheathed with Corrugated Steel Sheets ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011859/.
Texte intégralRésumé :
This thesis presents experiments and numerical analysis of a novel cold-formed steel framed shear wall sheathed with corrugated steel sheets. The objective of this newly designed shear wall is to meet the growing demand of mid-rise buildings and the combustibility requirement in the International Building Code. The strength of the novel shear wall is higher than currently code certified shear wall in AISI S400-15 so that it could be more favorable for mid-rise building in areas that are prone to earthquakes and hurricanes. Full-scale monotonic and cyclic tests were conducted on bearing walls and shear walls under combined lateral and gravity loads. Though the gravity loads had negative effects on the strength and stiffness of the shear wall due to the buckling of the chord framing members, it still shows promise to be used in mid-rise buildings. The objective of numerical analysis is to quantify the seismic performance factors of the newly design shear wall lateral-force resisting system by using the recommended methodology in FEMA P695. Two groups of building archetypes, story varied from two to five, were simulated in OpenSees program. Nonlinear static and dynamic analysis were performed in both horizontal directions of each building archetype. Finally, the results of the performance evaluation verified the seismic performance factors(R=Cd=6.5 and Ω =3.0) were appropriate for the novel shear wall system.
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Seelam, Praveen Kumar Reddy. « Direct Strength Method for Web Crippling of Cold-formed Steel C-sections ». Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271893/.
Texte intégralRésumé :
Web crippling is a form of localized buckling that occurs at points of transverse concentrated loading or supports of thin-walled structural members. The theoretical computation of web crippling strength is quite complex as it involves a large number of factors such as initial imperfections, local yielding at load application and instability of web. The existing design provision in North American specification for cold-formed steel C-sections (AISI S100, 2007) to calculate the web-crippling strength is based on the experimental investigation. The objective of this research is to extend the direct strength method to the web crippling strength of cold-formed steel C-sections. ABAQUS is used as a main tool to apply finite element analysis and is used to do the elastic buckling analysis. The work was carried out on C-sections under interior two flange (ITF) loading, end two flange (ETF) loading cases. Total of 128 (58 ITF, 70 ETF) sections were analyzed. Sections with various heights (3.5 in.to 6 in.) and various lengths (21 in. to 36 in.) were considered. Data is collected from the tests conducted in laboratory and the data from the previous researches is used, to extend the direct strength method to cold formed steel sections. Proposing a new design for both the loading cases and calculation of the resistance factors under (AISI S100, 2007) standards is done.
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McKelvey, Sean Ambrose. « Influence of Surface Finish on Bending Fatigue of Forged Steel Including Heating Method, Hardness, and Shot Cleaning Effects ». University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302110057.
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Silva, Ronisi Cazeli Gomes da. « Fundamentos teóricos e aspectos gerais para projetos de estruturas em aço com perfis conformados a frio ». Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-02052018-092942/.
Texte intégralRésumé :
Aborda-se os principais aspectos da fundamentação teórica relativos ao dimensionamento de elementos em aço, constituídos por perfis de chapa dobrada, baseados nas prescrições das normas Americana e Canadense. A fundamentação teórica destina-se a justificar os procedimentos referentes ao dimensionamento de perfis de aço conformados a frio, em particular os elementos comprimidos e fletidos, além dos aspectos da flambagem local destes perfis. Aborda-se também uma análise dos métodos de projeto das estruturas metálicas formadas por estes perfis, apresentando-se algumas disposições e alguns aspectos interessantes e essenciais no desenvolvimento de um edifício industrial leve. Tendo em vista a grande utilização dos perfis conformados a frios em terças, desenvolveu-se uma sistemática de cálculo fornecendo os valores dos momentos admissíveis que poderão ser aplicados para um pré-dimensionamento.An analysis of the theoretical basis for the design of cold-formed steel structural members, according to the American and Canadian Standards, is made. The theoretical background is used to justify the procedure to obtain the required geometry of the cold-formed steel structural members particularly the compression and flexural members, also to explain some aspects of the local buckling. Furthermore, an analysis of the design method of steel structures with these profiles is made. Some interesting and essential aspects are presented in what concerns to the development of a light industrial building. Having in mind the intensive use of cold-formed members in purlin structures, a procedure for systematic calculation was developed to determine the allowable bending moment values that can be used on a preliminary design.
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Truong, An Nhien. « Structural Behaviour of Power-Actuated Fasteners in Hybrid Steel Connections ». Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/28746.
Texte intégralRésumé :
This thesis presents research into a novel connecting method using Power-Actuated Fasteners (PAFs) in hybrid steel connections comprised of cold-formed steel (CFS) and hot-rolled steel.
The first experimental program investigated the shear behaviour of PAF connections in three different limit states: (i) bearing, (ii) shear fracture, and (iii) pull-out by shear. The test results validated the design provisions of PAF connections in AS/NZS 4600:2018 and AISI S100-16 with suggested revisions. Numerical investigations using Finite Element Analysis were conducted using ABAQUS. Various aspects of the models (i.e. fracture criteria, mesh sensitivity) were thoroughly examined and discussed.
In the second experimental program, Cross-Tension tests were carried out to investigate the behaviour of PAF connections under tension loading. An analytical model is proposed to evaluate the pull-out strength of the PAF connections. Reliability analyses are carried out to evaluate the capacity reduction factor of the proposed model for LRFD/LSD.
The third experimental program used a dual-actuator test apparatus to test full-scaled PAF connections joining CFS channels to rectangular hollow sections. The test results revealed the detrimental effect of the rotation on the shear capacity in two different limit states: (i) bearing and (ii) pull-out by shear. An analytical model is proposed to capture the shear-rotation relationship of PAF connections subjected to shear-rotation. Design proposals are made with two design examples to illustrate the implementation of the proposed model in the conventional design routine.
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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/.
Texte intégralRésumé :
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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Reynolds, James Bernard. « Advanced analysis and reliability-based design of steel scaffolding systems ». Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11626.
Texte intégralRésumé :
This thesis presents a comprehensive investigation of the advanced analysis, reliability-based design and optimisation of steel support scaffolding systems. Support scaffolding systems are used to provide temporary support to timber formwork systems, reinforcement, concrete, workmen and equipment, during the construction of permanent structures such as buildings and bridges. Stick-type steel scaffolds with cuplok joints are the focus of the thesis. This thesis includes the collection and statistical analysis of shore load effects occurring as a result of construction dead and live loads. A comprehensive series of U-head joint subassembly tests, allowed the top rotational stiffness to be rationally quantified for advanced finite element modelling. Advanced finite element models are calibrated using data compiled in a previous investigation involving eighteen full-scale tests. This calibration exercise also provides statistical data for modelling error. Monte Carlo simulations using advanced analysis are performed to determine the statistical distributions of system strength for a range of geometric configurations of support scaffold systems. The research showed that system strength was governed mainly by jack extension at the top and bottom of the scaffolding system. By incorporating the load statistics and system strength statistics, the thesis determined the reliability of various steel scaffolding systems designed by the fundamental Load-Resistance-Factor-Design (LRFD) equation. The study further proposed a more efficient LRFD equation for steel scaffolding, based on an acceptable target reliability index.
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Vora, Hitesh. « Shear Wall Tests and Finite Element Analysis of Cold-Formed Steel Structural Members ». Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9726/.
Texte intégralRésumé :
The research was focused on the three major structural elements of a typical cold-formed steel building - shear wall, floor joist, and column. Part 1 of the thesis explored wider options in the steel sheet sheathing for shear walls. An experimental research was conducted on 0.030 in and 0.033 in. (2:1 and 4:1 aspect ratios) and 0.027 in. (2:1 aspect ratio) steel sheet shear walls and the results provided nominal shear strengths for the American Iron and Steel Institute Lateral Design Standard. Part 2 of this thesis optimized the web hole profile for a new generation C-joist, and the web crippling strength was analyzed by finite element analysis. The results indicated an average 43% increase of web crippling strength for the new C-joist compared to the normal C-joist without web hole. To improve the structural efficiency of a cold-formed steel column, a new generation sigma (NGS) shaped column section was developed in Part 3 of this thesis. The geometry of NGS was optimized by the elastic and inelastic analysis using finite strip and finite element analysis. The results showed an average increment in axial compression strength for a single NGS section over a C-section was 117% for a 2 ft. long section and 135% for an 8 ft. long section; and for a double NGS section over a C-section was 75% for a 2 ft. long section and 103% for an 8 ft. long section.
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Nwachukwu, Chinedu Maureen. « Utilising forest biomass in iron and steel production : investigating supply chain and competition aspects ». Licentiate thesis, Luleå tekniska universitet, Energivetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-82997.
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Bock, Montero Marina. « Web crippling and local buckling response of stainless steel sections ». Doctoral thesis, Universitat Politècnica de Catalunya, 2015. http://hdl.handle.net/10803/285582.
Texte intégralRésumé :
This thesis examines the response of stainless steel members when subjected to transverse and normal forces triggering the instability phenomena called web crippling and local buckling, respectively. Currently, the part of Eurocode dealing with stainless steel, EN 1993-1-4 (2006) misses design provisions for web crippling and the applicability of some of its aspects is yet to be fully verified especially for application to ferritic stainless steel.
The first part of the thesis laid in the development of design equations for the treatment of web crippling in stainless steel sections which are currently designed following specifications given in EN 1993-1-3 (2006) for cold-formed carbon steel. Two design approaches were derived covering austenitic and ferritic stainless steels: an empiric equation, in line with the current provisions for web crippling design given in EN 1993-1-3 (2006); and an alternative semi-empiric design method based on strength curves which enables a better understanding of the phenomenon and showed to significantly improve web crippling predictions.
For the second part of the thesis, the applicability of the local buckling design provisions given in EN 1993-1-4 (2006) to ferritic stainless steel was examined giving focus to the slenderness limits and the effective width equations. The results showed that EN 1993-1-4 (2006) can safely be applied to ferritic stainless steel, though the code is rather conservative in comparison with other methods. Finally, a modification of the effective width equation incorporating element interaction effects was proposed which allows an improvement of cross-section capacity predictions and enables to amend the effective width method to the same level of alternative design approaches but promoting the use of the concepts currently considered in Eurocode.Esta tesis estudia la respuesta estructural de elementos de acero inoxidable sometidos a fuerzas transversales i normales que desencadenan los fenómenos de inestabilidad llamados web crippling y local buckling, respectivamente. Actualmente, la parte de Eurocódigo que contempla los aceros inoxidables, el EN 1993-1-4 (2006) carece de ecuaciones de diseño para web crippling y la aplicabilidad de algunas de sus especificaciones necesita ser validada especialmente para los aceros inoxidables ferríticos. La primera parte de esta tesis se focaliza en el desarrollo de ecuaciones de diseño para el tratamiento del web crippling en secciones de acero inoxidable que actualmente se diseñan siguiendo las especificaciones dadas en EN 1993-1-3 (2006) para acero al carbono conformado en frío. Dos métodos de diseño para los aceros inoxidables austeníticos y ferríticos: una ecuación empírica en línea con la actual dada en EN 1993-1-3 (2006); y un método de diseño semi-empírico basado en curvas de resistencia que permite entender mejor el fenómeno y muestra una mejora importante de las predicciones a web crippling. Para la segunda parte de la tesis, se ha estudiado la aplicabilidad de las actuales especificaciones para el diseño a local buckling dadas en EN 1993-1-4 (2006) a los aceros inoxidables ferríticos focalizándose en los límites de esbeltez y las ecuaciones de ancho eficaz. Los resultados mostraron que EN 1993-1-4 (2006) puede ser aplicado a los aceros inoxidables ferríticos, aunque el código es bastante conservador en comparación con otros métodos de diseño. Finalmente, se propuso una modificación de la ecuación del ancho eficaz que incorpora la interacción entre los elementos de la misma sección y que permite, además de mejorar las predicciones de la resistencia seccional, llevar el método del ancho eficaz hasta el mismo nivel que otros métodos de diseño pero ensalzando el uso de los conceptos actualmente considerados en Eurocódigo
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Dewaidi, Mohaned Ali. « Design Method for Cold-Formed Steel Shear Wall Sheathed with Polymer Composite Panel ». Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1707373/.
Texte intégralRésumé :
In order to predict the strength of shear wall with cold-formed steel framing members, analytical models were reviewed. Multiple analytical models were studied, as well as twenty-one connection tests were performed. The connection tests consist of 50-ksi cold-formed steel framing track, different fastening configurations, and different sheathing thicknesses (1/8" and 1/2"). No.12 screw resulted in the highest peak load of all fastening configurations, while the rivet connection had the lowest peak load. In addition, failure modes were observed after conducting the connection tests including shear in fastening, screw pullout, and bearing in the sheathing. However, only the rivet and No.10 screw fastening configurations were used in the prediction analysis of the shear wall by the elastic model. Six shear wall tests were conducted on both panels (1/2"and 1/8" thickness). After doing the comparison between the experimental and the elastic model, the percentage difference for the 1/8" and the 1/2" polymer composite panels (3''along the edge and 6''along the chord stud), was very small. It was 6.2% for the 1/8" and 2.96% for the 1/2" panels. This means the analytical model can predict the shear wall peak load. However, the percentage difference was slightly higher being 7.4% for the 1/2" polymer composite panels with 6" along the perimeter with the 12" at the chord stud. After comparing the experimental values to the predicted value of shear walls, it was concluded that this model is the most appropriate analytical method for predicting the shear wall capacity framed with cold-formed steel sheathed with polymer composite panels. Many of these configurations were used in a prototype shelter that was constructed and built at the structural testing laboratory at the University of North Texas.
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Reynolds, Kevin Brandt. « Evaluation of the flexural strength of cold-formed steel studs with embossed flanges ». Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1504.
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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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Derrick, Nathan Lynn. « Shear and Bending Strength of Cold-Formed Steel Solid Wall Panels Using Corrugated Steel Sheets for Mobile Shelters ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062814/.
Texte intégralRésumé :
The objective of this thesis is to determine if the single sided resistance spot weld (RSW) can be used as a feasible connection method for cold formed steel (CFS) shear walls subject to lateral force of either seismic or wind loads on mobile shelters. The research consisted of three phases which include: a design as a 3D BIM model, connection tests of the resistance spot weld, and full-scale testing of the designed solid wall panels. The shear wall testing was conducted on specimens with both resistance spot weld and self-drilling screws and the results from tests gave a direct comparison of these connections when the solid wall panel was subjected to in-plane shear forces. The full-scale tests also included 4-point bending tests which was designed to investigate the wall panel's resistance to the lateral loads applied perpendicularly to the surface. The research discovered that the singled sided resistance spot weld achieved similar performance as the self-drilling screws in the applications of CFS wall panels for mobile shelters. The proposed single sided resistance spot weld has advantages of low cost, no added weight, fast fabrication, and it is a feasible connection method for CFS wall panels.
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Gunawan, Leonardus. « Numerical models to simulate the thermal performance of LSF wall panels ». Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/49856/1/Leonardus_Gunawan_Thesis.pdf.
Texte intégralRésumé :
Fire safety of buildings has been recognised as very important by the building industry and the community at large. Gypsum plasterboards are widely used to protect light gauge steel frame (LSF) walls all over the world. Gypsum contains free and chemically bound water in its crystal structure. Plasterboard also contains gypsum (CaSO4.2H2O) and calcium carbonate (CaCO3). The dehydration of gypsum and the decomposition of calcium carbonate absorb heat, and thus are able to protect LSF walls from fires. Kolarkar and Mahendran (2008) developed an innovative composite wall panel system, where the insulation was sandwiched between two plasterboards to improve the thermal and structural performance of LSF wall panels under fire conditions. In order to understand the performance of gypsum plasterboards and LSF wall panels under standard fire conditions, many experiments were conducted in the Fire Research Laboratory of Queensland University of Technology (Kolarkar, 2010). Fire tests were conducted on single, double and triple layers of Type X gypsum plasterboards and load bearing LSF wall panels under standard fire conditions. However, suitable numerical models have not been developed to investigate the thermal performance of LSF walls using the innovative composite panels under standard fire conditions. Continued reliance on expensive and time consuming fire tests is not acceptable. Therefore this research developed suitable numerical models to investigate the thermal performance of both plasterboard assemblies and load bearing LSF wall panels. SAFIR, a finite element program, was used to investigate the thermal performance of gypsum plasterboard assemblies and LSF wall panels under standard fire conditions. Appropriate values of important thermal properties were proposed for plasterboards and insulations based on laboratory tests, literature review and comparisons of finite element analysis results of small scale plasterboard assemblies from this research and corresponding experimental results from Kolarkar (2010). The important thermal properties (thermal conductivity, specific heat capacity and density) of gypsum plasterboard and insulation materials were proposed as functions of temperature and used in the numerical models of load bearing LSF wall panels. Using these thermal properties, the developed finite element models were able to accurately predict the time temperature profiles of plasterboard assemblies while they predicted them reasonably well for load bearing LSF wall systems despite the many complexities that are present in these LSF wall systems under fires. This thesis presents the details of the finite element models of plasterboard assemblies and load bearing LSF wall panels including those with the composite panels developed by Kolarkar and Mahendran (2008). It examines and compares the thermal performance of composite panels developed based on different insulating materials of varying densities and thicknesses based on 11 small scale tests, and makes suitable recommendations for improved fire performance of stud wall panels protected by these composite panels. It also presents the thermal performance data of LSF wall systems and demonstrates the superior performance of LSF wall systems using the composite panels. Using the developed finite element of models of LSF walls, this thesis has proposed new LSF wall systems with increased fire rating. The developed finite element models are particularly useful in comparing the thermal performance of different wall panel systems without time consuming and expensive fire tests.
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Neubert, Michael Christopher. « Estimation of Required Restraint Forces in Z-Purlin Supported, Sloped Roofs Under Gravity Loads ». Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/44512.
Texte intégralRésumé :
The current specification provisions for the prediction of lateral restraint forces in Z-purlin supported roof systems under gravity loads are in Section D3.1 of the 1996 AISI Cold-Formed Specification. The design equations contained in these provisions are empirical and based on statistical analysis. They were developed using elastic stiffness models of flat roofs and were verified by experimental testing. The provisions need refinement, because the treatment of roof slope and system effects is incorrect. Also, the current design provisions are based upon an assumed panel stiffness value, ignoring the significant difference in required restraint force that occurs when panel stiffness is varied.
Therefore, a new restraint force design procedure, having a stronger reliance on engineering principles, is proposed. This new treatment of the static forces in Z-purlin roofs led to a more accurate method of addressing roof slope. Elastic stiffness models, with varying roof slope, panel stiffness, and cross-sectional properties, were used to develop the proposed procedure. The basis of the procedure is to determine the lateral restraint force required for a single purlin system and then extend this result to systems with multiple restrained purlin lines. Roof slope is incorporated into the calculation of the single purlin restraint force, which includes eccentric gravity loads and forces induced by Z-purlin asymmetry. The procedure includes a system effect factor to account for the observed nonlinear increase in restraint force with the number of restrained purlins. An adjustment factor varies the predicted restraint force depending on the shear stiffness of the roof panel. The proposed procedure applies to five bracing configurations: support, third-point, midspan, quarter point, and third-point plus support restraints.Master of Science
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Martin, Geoff. « Investigation of the slip modulus between cold-formed steel and plywood sheathing ». Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/17568.
Texte intégralRésumé :
Master of ScienceDepartment of Architectural Engineering and Construction Sciences
Kimberly Waggle Kramer
Bill Zhang
Cold-formed steel members quickly are becoming a popular material for both commercial and residential construction around the world. Their high strength to weight ratio makes them a viable alternative to timber framing. In most cases cold-formed steel is used as a repetitive member in floor, wall, or roof assemblies. Structural sheathing is used in conjunction with the framing members in order to transfer loads between individual members. This sheathing is connected mechanically to the cold-formed steel through a variety of methods. The most common method uses screws spaced at close intervals, usually between 6 to 12 inches on center. When such assemblies are constructed, load is transferred from the sheathing through the connectors into the cold-formed steel, forming a composite assembly in which load is transferred and shared between two materials, providing a higher strength and stiffness over individual members themselves. The amount of load that can be transferred is dependent on the amount of slip that occurs when the assembly is loaded. This slip value describes the amount of composite action that takes place in the assembly. The amount of slip can be described by a value called the slip modulus. The composite, or effective, bending stiffness can be calculated using the slip modulus. In current design of cold-formed steel composite assemblies this composite action is not being taken into account due to a lack of research and understanding of the composite stiffness present in these assemblies. Taking composite action into account can lead to decreased member sizes or increased spacing of members, thereby economizing design. Furthermore, improved understanding of the effective stiffness can lead to more accurate design for vibrations in floor systems. This thesis tests cold-formed steel plywood composite members in an effort to verify previously established slip modulus values for varying steel thicknesses and establishes new values for varying fastener spacings. The slip modulus values obtained are used to calculate effective bending stiffness values in an effort to prove that composite action should be utilized in design of cold-formed steel composite assemblies.