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In this paper, a novel corrugated steel sheet central sheathed cold-formed steel (CCS-CFS) shear wall is proposed. This shear wall can address the problems of low shear strength and ductility in conventional cold-formed steel (CFS) shear walls caused by screw connection failure and eccentric sheet arrangement. A numerical simulation method for the novel shear wall was developed and verified through cyclic loading test results of two full-size shear wall specimens. Parameter analysis was then conducted to investigate the effects of screw spacing, sheet thickness ratio, and aspect ratio on the seismic performance of these shear walls, accompanied by design recommendations. The results indicated that this innovative shear wall configuration can effectively resolve the connection failure between the frame and the sheet. Furthermore, the CCS-CFS shear wall can effectively improve shear strength, energy dissipation capacity, and ductility. The developed numerical simulation method can accurately capture the hysteretic properties and failure modes of shear walls. In addition, it can address the shortcomings in conventional models that neglect the mixed hardening characteristic of steel and metal damage criteria, resulting in inaccurate simulation results and unrealistic buckling modes. The principal failure modes observed in the novel shear wall were identified as the plastic buckling of corrugated steel sheathing and the distortional buckling of the end stud. Reducing the screw spacing has a limited impact on its shear strength. It is recommended that the sheet thickness ratio of the CCS-CFS shear wall should be greater than 2.0, while the aspect ratio can be relaxed to 10:4. [ABSTRACT FROM AUTHOR]

This paper proposes damage index–based limit-state criteria for seismic design of midrise cold-formed steel (CFS) buildings instead of the drift-based ones, and the Park-Ang damage model was used to calculate the damage indexes. Two 5-story CFS buildings with different wall configurations were tested, and a test-validated numerical model was developed. An incremental dynamic analysis was conducted on a typical midrise CFS building to obtain the degradation parameter β of different CFS walls. The damage indexes computed from numerical analyses were compared with the damage indexes estimated from test observations and the proposed damage index–based limit-state criteria. The results showed that the calculated degradation parameter as well as the proposed damage index–based limit-state criteria are effective for seismic damage assessment and damage level classification of midrise CFS buildings according to the validations by shaking-table tests on two CFS buildings. The Park-Ang damage index used in this paper and the proposed limit-state criteria could be used for performance-based seismic design of midrise CFS buildings. [ABSTRACT FROM AUTHOR]

Although cold-formed steel (CFS) framing systems have the potential to support the need for resilient housing, the use of CFS has been restricted due to gaps in understanding its structural behavior and by the limited guidelines provided in design standards. In particular, the contribution from nondesignated lateral systems and portions of the building system not specifically designated by the design engineers has not been substantially investigated through experiments. To address these shortcomings, a two-phased experimental effort was undertaken to assess the impact of gravity walls, finish application, window openings, and their relationship with the designated lateral force–resisting system. The wall-line assemblies tested, which have shear walls placed in-line with gravity walls, adopted chord stud packs with a tie-rod assembly and were either unfinished or finished, and laid out in a symmetrical or unsymmetrical fashion. In addition, both Type I and Type II shear wall and anchorage detailing were investigated. In this paper, the impact of test variables governing the nonstructural detailing of CFS-framed walls has been quantified, and a companion paper presents findings regarding the impact of structural detailing. [ABSTRACT FROM AUTHOR]

The North American construction industry has seen substantial growth in the use of cold-formed steel (CFS) framing for midrise buildings in recent years. In seismic zones, CFS-framed buildings utilize shear walls to provide the primary lateral resistance to earthquake induced loads. Although oriented strand board (OSB) and plywood panels have been traditionally used as the sheathing material for these essential components, more recently, steel sheet sheathing has emerged as a novel strategy due to its strength, ductility, ease of installation, and use of noncombustible material, among other benefits. To address the paucity of data regarding CFS-framed shear wall response within actual wall lines of buildings, a two-phased experimental effort was conducted. Wall-line assemblies were fabricated and tested with shear walls placed in-line with gravity walls. The shear walls chord stud packs include tie-rod assemblies consistent with multi-story detailing. Specimens were either unfinished or finished, and the shear walls were laid out in a symmetrical or unsymmetrical fashion within in the wall line. In addition, both Type I and Type II shear wall and anchorage detailing were investigated. In this paper, the impact of test variables governing the structural detailing of CFS-framed walls are quantified through dynamic and quasi-static tests, and a companion paper presents findings regarding the impact of architectural variations on seismic performance. [ABSTRACT FROM AUTHOR]

The cold-formed steel shear wall with steel sheathing has gained increasing popularity due to its excellent shear capacity. To extend the applicability of this system to multi-story residences, aside from experimental investigations on the shear walls, it is essential to conduct a comprehensive study on the seismic performance of buildings. In this paper, numerical simulations were conducted on specimens subjected to monotonic and cyclic loading. Subsequently, seismic analysis of mid-rise building models was also carried out to investigate the influence of the proposed shear wall on building seismic performance. The research findings indicate that this study's modeling method can effectively simulate the shear performance of the proposed shear wall under monotonic and cyclic loading. In addition, the proposed shear wall significantly enhances the structural stiffness and improves the seismic performance of the structure under seismic action. [ABSTRACT FROM AUTHOR]

The objective of this paper is to employ the results from the extensive instrumentation installed on recently tested full-scale cold-formed steel (CFS)-framed buildings to reveal a deeper understanding of the behavior of the building under seismic excitations. In particular, this paper complements a companion paper that focuses on system-level design and response. Here, utilizing strategically located string potentiometers, strain gauges, and accelerometers, the responses of the walls and diaphragms are isolated from the overall building response and studied. The interaction of shear walls along a wall line, as well as across stories is studied through measured data on strains in hold-down anchors, strains on floor-to-floor strap connecting shear-wall chord studs, and displacements across shear-wall sheathing and openings. The behavior of the floor diaphragm is studied through displacements measured perpendicular to the plane of one wall of the building and accelerometers throughout the floor of the building. The results serve to highlight the subsystem-level outcomes that accompany the complex system-level response as CFS-framed buildings undergo seismic excitations. [ABSTRACT FROM AUTHOR]

Complementing a companion paper that summarizes the building global response and physical damage of a midrise cold-formed steel (CFS) framed building during an earthquake and postearthquake fire test program, this paper focuses on understanding the seismic behavior of the shear walls utilized in the building system during this test program. In contrast to shear walls tested in an isolated configuration, the shear walls within the full-scale test building were constructed and tested under real-world kinematic constraints and dynamic loading environments. The shear walls located at various planar and vertical locations of the test building were instrumented with a dense array of analog sensors to monitor the shear wall local responses. In this study, the shear wall local responses are correlated with the global responses of the building to advance understanding regarding the behavioral characteristics of individual shear walls and in particular the interactions of the shear walls as part of the lateral-load-resisting system. Important seismic design parameters are inferred from the measured building response using a parameter optimization strategy. Their implications associated with the seismic design of CFS wall-framed structural systems are discussed in relation to code provisions and design guidelines. [ABSTRACT FROM AUTHOR]

To advance understanding of the multihazard performance of midrise cold-formed steel (CFS) construction, a unique multidisciplinary experimental program was conducted on the Large High-Performance Outdoor Shake Table (LHPOST) at the University of California, San Diego (UCSD). The centerpiece of this project involved earthquake and live fire testing of a full-scale 6-story CFS wall braced building. Initially, the building was subjected to seven earthquake tests of increasing motion intensity, sequentially targeting service, design, and maximum credible earthquake (MCE) demands. Subsequently, live fire tests were conducted on the earthquake-damaged building at two select floors. Finally, for the first time, the test building was subjected to two postfire earthquake tests, including a low-amplitude aftershock and an extreme near-fault target MCE-scaled motion. In addition, low-amplitude white noise and ambient vibration data were collected during construction and seismic testing phases to support identification of the dynamic state of the building system. This paper offers an overview of this unique multihazard test program and presents the system-level structural responses and physical damage features of the test building throughout the earthquake-fire-earthquake test phases, whereas the component-level seismic behavior of the shear walls and seismic design implications of CFS-framed building systems are discussed in a companion paper. [ABSTRACT FROM AUTHOR]

To overcome the shortcomings of traditional shear walls, structure systems have been proposed and investigated. One such structure system is a steel-reinforced concrete shear wall, which has certain desirable properties such as good load-bearing capacity, stiffness, and seismic performance. This paper proposes an M-section cold-formed thin-walled steel reinforced concrete (MCTSR) shear wall, which uses M-section cold-formed thin-walled steel to function as reinforcements. Six specimens with different permanent formwork types, axial compression ratios, reinforcement diameters, and other parameters were tested under cyclic loading to investigate seismic performance. The results demonstrate that various types of permanent formwork, including cement fibrolite plate, metal lathing, and polystyrene board can meet the requirement of related seismic design codes, construction demand, and assembly requirements, and have no obvious impact on the ultimate load-bearing capacity, lateral stiffness, and stiffness degradation rate. However, it changes the energy dissipation capacity and ductility, which are two important indexes to evaluate seismic performance in engineering practice. The failure mechanism and the influence of axial compression ratio, reinforcement diameter, and space between reinforcements are discussed. The shear-strength equations proposed by various countries' or regions' codes were analyzed, which can be used as a reference for related engineers and designers. Finite-element models for MCTSR shear walls were established for further investigation. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of an innovative configuration for cold-formed steel (CFS) framed shear walls using corrugated steel sheets as sheathing material. The shear wall configuration comprises corrugated steel sheathings placed inside the steel framing and therefore is known as an in-frame or sheet-in shear wall. The innovative shear wall configuration is noncombustible, is equal in thickness to adjacent walls, and avoids the difficulties inherent in the design and installation of the finish materials used in common corrugated steel sheathed shear walls. The test program in this research comprised cyclic testing of five groups of shear walls in which the stud arrangement, sheathing continuity, framing thickness, and wall aspect ratio varied. The results indicate that shear walls with a lower-profiled field stud and continuous sheathing had satisfactory performance with balanced shear strength and ease of assembly. Based on the test data, shear resistances of in-frame or sheet-in shear walls with corrugated steel sheathing under seismic load are recommended as the basis for design. These innovative shear walls exhibited substantially higher shear capacity than code-certified shear walls, and therefore can be used as a substitute for a lateral force–resisting system in midrise CFS light-framed buildings. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental study on the behavior of the cold- formed steel shear wall panel (CFSSWP) with fibrocement panels as sheathing, when it is subjected in-plane shear deformations and flexural deformation under perpendicular monotonically increasing horizontal loads on the longest plane. A full-scale housing section was built with three walls and a ceiling using commonly used construction details in El Salvador. The strength and stiffness of the experimental specimen tested overcame significantly critical demand imposed by the technical design standards in this country. Additionally, a simplified finite element model was defined with the objective to analyze stresses in the components. The results of the numerical model were similar to the experimental model tested. [ABSTRACT FROM AUTHOR]

This study developed a special energy dissipation X-bracing for cold-formed steel (CFS) shear walls to improve the ductility of the corrugated steel sheathing. In previous research, CFS shear walls with corrugated sheathing demonstrated poor ductility under cyclic loading. The paper presents a potential solution by adding a special energy dissipation bracing (EDB) to improve the ductility of the corrugated sheet–sheathed shear walls. The EDB can be tuned according to the CFS shear wall base performance to achieve the highest postpeak deflection capacity, thereby significantly improving the seismic ductility. To prove the concept and analyze the feasibility of the new EDB, a test program of nine full-scale shear walls was conducted. The experimental results showed that with the tuned EDB, the corrugated steel sheet–sheathed shear walls had improved ductility with no considerable reduction in the initial stiffness and shear strength. Installing the proposed EDB can be an efficient approach to enhance the seismic performance of CFS-framed shear walls. Details of the test program and discussion are presented. [ABSTRACT FROM AUTHOR]

Increasing the lateral strength and stiffness of light-frame structures can lead to reduced damage in the event of an earthquake. Because low-rise wood and cold-formed steel-framed buildings often contain many partition walls, their performance can be improved economically by more effective engagement of gypsum-sheathed walls. This paper describes a series of tests of enhanced screw and adhesive connections between gypsum wallboard and wood and cold-formed steel-framing members. Small wall panels constructed with the improved connections were also tested and compared with wallettes built with conventional drywall screws. Test results indicate that while enhanced screws can increase connection and wall strength modestly relative to conventional screws, a much more significant increase in strength and stiffness can be obtained by using construction adhesives. Test results show that supplementing conventional screws with adhesives increased connection strength and stiffness by a factor of four to five. These adhesive-supplemented connections in light-frame wallettes increased strength by approximately two times and stiffness by approximately three times when compared with wallettes with conventional screw connections alone. This paper describes the response and damage progression of gypsum wallboard connections and framed wallettes using the enhanced screw and adhesive connections. [ABSTRACT FROM AUTHOR]

Studies on the constructability of cold-formed steel (CFS) members are lacking. In this context, this paper proposes an integrated panel to replace the studs and steel sheet in the steel-sheathed wall system used in light gauge steel frames. The integrated panel was developed, to not only exhibit better structural performance and constructability than the steel-sheathed wall system, but to also reflect the appropriate details for applications to on-site panel construction. Cyclic loading tests were performed to investigate the seismic performances of three integrated panel specimens and a steel-sheathed panel specimen. The integrated panel specimens exhibited greater deformation capacity, ductility and equivalent damping ratio than the steel-sheathed panel. Although the web slenderness of the integrated member was nearly 400, the nominal strength of the integrated panel was predictable on an AISI standard. However, for stud-reinforced integrated panels, the nominal strength was overestimated by 45%–60%, and a draft equation was proposed to predict the yield strength of these panels. The proposed equation accurately predicted the yield strength of the stud-reinforced integrated panel specimens. The study results can aid in the construction of light gauge steel frames that require reinforcing parts with a high web slenderness ratio. [ABSTRACT FROM AUTHOR]

Lightweight EPS materials (LEM)-filled cold-formed steel (CFS) shear wall structure is a new type of green, low-carbon and prefabricated rural residence, which has drawn in expanding consideration due to the promotion of the rural revitalization strategy. However, most of the existing research on this type of residence has focused on its behaviours of components, with little attention was paid to its overall response to resist earthquake disasters. During the past two decades, significant advancements have been made in effectively mitigating building collapses and reducing casualties resulting from earthquakes. Thus, the concept of seismic resilience is proposed, and the seismic performance requirements of structural design have been elevated from "safety" to "resilience". To analyze the seismic resilience of LEM-filled CFS residence, this paper proposed a strut and tie- equivalent spring model to establish the simplified analysis model of a single composite wall, and the precision of the model was confirmed by test results, in which the nonlinear characteristic and the supporting effect of fillers was considered. Subsequently, three LEM-filled CFS residences are designed using the direct displacement-based design method. Then the three-D models are established for nonlinear analysis, and the inter-drift ratio (IDR) and residual inter-drift ratio (RIDR) are adopted to estimate the seismic response of the three archetypes. The seismic resilience of the three archetypes are assessed based on FEMA P58. This paper would provide a guidance for the nonlinear analysis and seismic resilience assessment of this type of residences, and promote the application and popularization of this kind of residence. • A simplified equivalent model is proposed to analysis the seismic performance of LEM-infilled CFS shear wall. • Three LEM-filled CFS residences are designed using the DDBD method based on the calculated equivalent viscous damping. • The seismic resilience of the three archetypes are assessed based on FEMA P58. [ABSTRACT FROM AUTHOR]

Offering the advantages of non-combustibility, high shear strength, and high shear stiffness, a cold-formed steel (CFS) shear wall sheathed with corrugated steel sheets (CSS) is a promising shear wall system for low- and mid-rise constructions in high wind and seismic zones. As the primary lateral force-resistant component of CFS structures, the lateral response of CSS sheathed shear wall is primarily determined by the CFS-to-sheathing screwed connections. The connection performance of screws in CFS walls was determined by a combination of shear and tensile forces, with a particular focus on the shear performance parallel to the corrugation direction within the plane. The series of experiments reported in this paper characterize the hysteretic behavior of the screwed connections between CFS studs and sheathing panel under shear loading. Experimental tests were conducted in order to generate the hysteretic responses of CFS-to-CSS screwed connections with varied sheathing panel types, sheathing thicknesses, screw spacings, and edge distances. The results indicated that the test phenomena observed in the screwed connection between CFS and sheathing panel during the entire loading process were generally a combination of several failure modes, which was predominantly influenced by the sheathing thickness, the end distance, and the loading method. The peak load of the specimens under monotonic loading were greater than that under cyclic loading and increased almost linearly with the increase in sheathing thickness. Referring to North American code provisions, a calculation method for the strength of CFS-to-CSS screwed connections was proposed. Finally, based on the experimental data, a hysteretic constitutive model for CFS-to-CSS screwed connection was established. This model serves as preliminary preparation for the refined numerical simulation of corrugated steel sheathed shear wall. • The hysteretic performance of CFS-to-CSS screwed connections was investigated experimentally. • The test phenomena and failure modes of theCFS-to-CSS screwed connections were explored. • A hysteretic constitutive model for CFS-to-CSS screwed connections was established based on test data. [ABSTRACT FROM AUTHOR]

Abstract Recent research showed that shear walls with corrugated steel sheathing demonstrated high strength, high initial stiffness but low ductility under cyclic loading and thus were not favorable for seismic applications. A possible solution by creating openings in the field of the corrugated sheets in order to improve the ductility was newly proposed by the authors. This paper presents an experimental study on the seismic behavior of the cold-formed steel shear walls using corrugated steel sheathings with different slits configurations. A total of 14 full scale shear wall specimens, including seven different slit configurations and one unperforated wall configuration, were tested under lateral cyclic loading. The test results indicate that with proper slit configurations on the sheathing, the corrugated steel sheathed shear wall shows an improved high ductility without significant reduction in shear strength and stiffness. Details of the test program and general results are presented in this paper. Highlights • Comprehensive experimental program on corrugated sheet cold-formed steel shear wall with slits • New sheathing design improves seismic ductility of the cold-formed steel shear wall and avoids unfavorable failure modes. • The new shear wall system is an ideal solution for mid-rise light framed steel building in seismic zone. [ABSTRACT FROM AUTHOR]

The aim of this paper was to present a verified finite element method that represents the full-scale-braced shear walls under seismic loads and to study their ductility. The models account for different types of material and geometric nonlinearities. The screws that connect the cold-formed-steel (CFS) studs, tracks, gusset plates, and braces are considered explicitly in the model. The deformation of the hold-downs under the horizontal load is considered. The finite element program ANSYS (2012) is used to model and analyze the case studies. A parametric study is performed to investigate the response modification factor (R) of the CFS-braced shear walls. The parametric study showed that the North American Specification is about 20% conservative in estimating the (R) factor. [ABSTRACT FROM AUTHOR]

An innovative cold-formed steel center-sheathed shear walls (CFSCSSWs) was proposed in this paper to improve the horizontal load-carrying capacity of conventional cold-formed steel walls. However, the fire behavior of this wall configuration was particularly worthy of attention because it was designed to be used in multi-story buildings, and there is still a lack of in-depth exploration of the fire performance and high-temperature horizontal load-bearing capacity of CFSCSSWs under combined loads. In this study, a compression test was first carried out to obtain the vertical load-carrying capacity of a full-scale CFSCSSW, followed by a fire test on a similar CFSCSSW subjected to combined vertical and horizontal loads to investigate the fire behavior of walls. Then, a finite element model was established and validated by test results to investigate the influence of various critical factors, including vertical and horizontal load ratios, height-width ratio, and sheathing thickness, on the fire behavior of the CFSCSSW. The results showed that the vertical load ratio presented a larger influence on the fire behavior of CFSCSSWs compared to the horizontal load ratio. The increasing aspect ratio can slightly improve the fire resistance of the wall under the same load ratio. The wall with a 0.8 mm thick sheathing exhibits better fire behavior under the same load ratio. A high-temperature horizontal load-carrying capacity calculation method for CFSCSSWs was proposed, and its good accuracy was found. • Load capacity of cold-formed steel center-sheathed shear wall was investigated experimentally and numerically. • Parametric analysis was conducted to investigate the influence of key parameters on the fire behavior of the wall. • A method for predicting high-temperature horizontal load capacity of the wall was proposed. [ABSTRACT FROM AUTHOR]

Conventional cold-formed steel wall systems suffer from low lateral loading-carrying capacities and stiffnesses, which represent the main barrier to their use in multi-story buildings. To address it, a cold-formed steel center-sheathed shear wall (CFSCSSW) system with higher lateral load-carrying capacity and better lateral structural performance is proposed. This paper presents experimental, numerical, and analytical studies on the behavior of the proposed CFSCSSW subjected to combined vertical and horizontal loads. Firstly, a full-scale test was conducted, with the test setup, loading procedures and measuring instrument reported in detail. The obtained test results, including the load-carrying capacity, failure mode and strains, were fully analyzed. Then, finite element modeling was conducted to simulate the experimental observations, and parametric studies were carried out to investigate the influences of different geometric and loading parameters on the behavior of CFSCSSWs. Finally, a three-strip model with a variable position on end studs (TSM-VPC) was proposed for CFSCSSWs and shown to accurately simulate the direction of the tensile field within the sheathing and also resulted in high accuracy in calculating the load-carrying capacities, followed by a design example. ● An innovative cold-formed steel center-sheathed shear wall (CFSCSSW) system is proposed. ● A full-scale test on CFSCSSW under combined loading is conducted, with test results fully analysed. ● The influences of key geometric and loading parameters are investigated through parametric studies. ● A three-strip model is proposed for calculating the load-carrying capacity of CFSCSSW. [ABSTRACT FROM AUTHOR]

The paper presents an experimental investigation of light-gauged cold-formed steel shear wall using corrugated steel sheets with circular holes. Corrugated steel sheathing has been shown to significantly increase the strength of the cold-formed steel shear walls but the ductility of the wall was not suitable for seismic applications. One possible solution involves creating openings in the corrugated sheets to improve the ductility. The test program included a total of 10 full-scale shear wall tests which had three different circular opening configurations and two nonperforated sheathing configurations. The research discovered that by having circular holes in the corrugated sheathing, the tested cold-formed steel shear walls could fail in sheathing ruptures instead of screw failures. The shear walls did gain ductility due to the new failure mode; however, the stiffness and strength of the shear walls were significantly reduced. It is therefore not recommended by the authors to use circular holes in corrugated sheets for the investigated cold-formed steel shear walls to gain ductility. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) framed shear walls with steel sheathing are promising lateral-force-resisting members of mid-rise buildings in seismic regions. Previous studies have demonstrated that steel sheathed CFS framed shear walls have high shear capacity but some shortcomings, such as the low ductility caused by the premature damage of the frame and the shear buckling of the sheathing. This paper presents an experimental study on a novel type of CFS framed shear wall with slitted steel sheathing (CFS-SSWs), which uses longitudinal slits to change the failure mode of the sheathing so that the ductility of the wall can be improved; Meanwhile, stiffeners are utilized to enhance the out-of-plane stability of the slitted sheathing and the integrity of the wall. Six full-scale CFS-SSW specimens were tested under monotonic and cyclic lateral loading. Three types of stiffening approaches (Type I, Type II and Type III) were adopted for the walls. Test results were analysed to investigate lateral performances of walls under different stiffener arrangements, including failure modes, load-displacement hysteresis curves, backbone curves, stiffness and strength degradation, and energy dissipation capacity. The measured strengths of the walls in the tests were assessed using theoretical indexes. It is found that peak loads and energy dissipation capacity of stiffened walls are noticeably higher than those of the unstiffened wall. Type II and Type III are effective stiffening approaches that could mitigate the buckling of the slitted sheathing and enable the links between the slits to reach the full plastic strength. By connecting the stiffeners and studs through stiffener connectors, Type III has the most significant enhancement on the stiffness, strength and ductility of the wall. • A novel type of cold-formed steel framed shear wall, i.e., CFS-SSW, is presented. • Six full-scale CFS-SSW specimens are tested to investigate their lateral behavior. • The stiffened walls show improved performances compared to the unstiffened wall. • Type II and III are effective stiffening methods that can mitigate the buckling. • Type III has the most significant enhancement on the performances of the wall. [ABSTRACT FROM AUTHOR]

• Shell FE-based modelling protocol for CFS sheathed shear walls has been developed. • UELs were implemented for modelling the sheathing-to-CFS screws shear behaviour. • Thirty-eight sheathed CFS shear walls were simulated under monotonic lateral load. • Effect of construction details on lateral behaviour of CFS walls was investigated. • Results showed conservatism in CFS walls design as per AISI S400-15 and SCI ED002. This paper investigates the effect of modular construction details on laterally-loaded cold-formed steel (CFS) framed shear walls sheathed with wood- and cement-based panels by means of finite-element (FE) analyses. Shell FE-based models have been developed in ABAQUS with the aim of accurately capturing the behaviour, strength and stiffness as well as the corresponding failure modes of CFS framed shear walls subjected to monotonic lateral load (i.e. , wind). User-defined element subroutines were adopted for precise modelling of sheathing-to-CFS screws shear behaviour. The proposed modelling protocol is validated using experimental test results, where an acceptable concordance (4% difference) has been achieved. Subsequently, the effect of modular construction details, which go beyond the scope of the current lateral design provisions (AISI S400), on the lateral behaviour of CFS framed shear walls is assessed. In particular, this paper investigates the impact of: (i) floor and ceiling ledger beams on the interior face of the shear wall, (ii) sheathing boards having different sizes from the overall shear wall and thus the presence of both vertical and horizontal seams, (iii) cement particle boards at the bottom stripe of the shear wall and (iv) different screw spacing in the top and bottom stripes from the middle part of the shear wall. The key parameters, which have most affected the lateral behaviour, were identified, and based on that, rules have been established for optimizing the screws pattern and sheathings layout efficacy in the above-described lateral load resisting system. The obtained results shed light on the capability of the developed modelling protocol to be used as a virtual test bench, particularly in offsite mass production and manufacture (DfMA), for the development of a new CFS framed wall system for lateral stability of lightweight modular houses. [ABSTRACT FROM AUTHOR]

This paper focuses on the deficiencies of Chinese standard GB/T 38591–2020, and combines the mechanical characteristics, post-earthquake damage characteristics, and repair methods of mid-rise cold-formed steel (CFS) structures to define the damage grade of structural components and revise various index parameters in the "Standard". Based on the calculation results of 120 sets of 6-story CFS composite shear wall structures, the multi-parameter seismic resilience evaluation index and grading criteria applicable to mid-rise CFS structures are fitted, and the index values (R values) for dividing the 5 resilience grades are 0.5, 1.0, 1.25, and 1.7, respectively. By considering different building usage functions and seismic effects, the 5-story CFS structure shaking table test models and the irregular eccentric CFS structure numerical model are used to jointly verify the reasonableness and universality of the seismic resilience evaluation index and grade classification criteria. The multi-parameter resilience evaluation index system lays the foundation for the study of seismic resilience of mid-rise CFS buildings and provides new ideas for establishing quantitative resilience evaluation indexes for different building systems. • The grading criteria and index parameters of CFS structural components are defined. • An Index Calculation Method applied to mid-rise CFS structures is established. • A muti-parameter resilience evaluation index for mid-rise CFS structures is proposed. • A comprehensive and reasonable seismic resilience grading criteria is established. • The universality of an index is verified by shaking table tests and numerical models. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation followed by numerical modeling for cold-formed steel (CFS) shear wall sheathed by fiber-cement board (FCB) under monotonic lateral load. Afterwards a numerical parametric study was performed taking into consideration various factors affecting the system ductility. The response modification factor was estimated using Equal Energy Elastic-Plastic rule. The results showed that the screw connections between the FCB and the steel framing members are of significant impact on the nonlinear behavior of the system. Also, the X-strap bracing increases the lateral load capacity and the values of response reduction factors (R) of the sheathed CFS shear walls. • The recommended screw spacing is between 100 and 200 mm. • Using noggin members improves the capacity of the shear wall. • The X-strap bracing significantly improves the lateral resistance of the shear wall. • Fiber cement board sheathing enhances the shear stiffness of the shear wall. • Average response reduction factor for this system of shear wall is equal to three. [ABSTRACT FROM AUTHOR]

Abstract The objective of this paper is to investigate the moment-rotation behavior of floor-to-wall connections used in ledger-framed cold-formed steel building construction with full-scale experiments. Recently completed research employing full-scale shake table tests on a two-story ledger-framed cold-formed steel framed building utilizing oriented strand board (OSB) sheathed shear walls and floors exhibited beneficial lateral system response that exceeded predictions. One hypothesis is that the stiffness of the floor-to-wall connections, and the repetitive nature of this connection, provided beneficial semi-rigid frame response that augmented the designed shear walls. Monotonic and cyclic full-scale connections were tested and reported here to examine the connection strength and stiffness, so that this hypothesis may be explored further in the future. The test matrix is designed to evaluate the presence of OSB floor sheathing, applied moment/shear ratio of the joist, joist-to-ledger clip angle location (inside or outside of the joist section), presence of top and bottom screws connecting the joist and ledger flanges, and location of the joist relative to the studs. The results indicate how the connection details and loading conditions drive the moment-rotation response; in addition, several limit states not checked in current design were also observed. Current design for this connection assumes a pure shear condition governed by screw shear capacity. However, ledger-to-stud screw pull-out, ledger flange buckling, and stud web crippling limit states are all observed in the testing. Design methods to support strength predictions consistent with the observed limit states are developed and assessed. The testing provides needed characterization of cold-formed steel floor-to-wall performance and is augmented by improved design methods for this detail. Highlights • Stiffness and failure modes in floor-to-wall connections for CFS framing provided. • Floor-to-wall connections in CFS framing may be subject to unexpected limit states. • Joists in CFS framing can potentially cripple studs at large rotation. • Ledger flange buckling is a favorable limit state in CFS floor-to-wall connections. • Design methods are provided to predict floor-to-wall CFS connection behavior. [ABSTRACT FROM AUTHOR]

This paper presents the results of an exploratory study performed to examine the potential of using bolted connections between perforated infill panels and the boundary elements of steel plate shear walls. Perforated infill panels have the advantage over solid infills in that these panels can be detailed to minimize the forces imposed to the panel connections and surrounding boundary members. Furthermore, addition of perforations will accommodate the use of thicker perforated infill panels where solid infill thinner panels may not be practical. For such applications, bolted connections can be used to improve the replaceability of the web panels after a strong earthquake to facilitate rapid repairability. Hence, the combination of bolted connections with perforated infill panels could lead to an overall effective design solution for steel plate shear walls. This paper presents the results of a shake table test program on one-third scale three-story specimens as a proof of concept on the use of bolted perforated infill panels. The experimental results are compared to those obtained with conventional solid infill panels welded to the boundary elements. The results demonstrated that perforated SPSWs with slip-resistant bolted infill panels of thin cold-formed steel can provide a hysteretic behavior and seismic performance comparable to SPSWs having with conventional solid infill panels with welded connections. • Perforated infill plates with bolted perimeter connections are a viable solution for seismic SPSWs. • Bolted perforated SPSWs can provide hysteretic seismic performance comparable to solid SPSWs. • Performance of slip-resistant bolted connections demonstrated by shake table experiments. [ABSTRACT FROM AUTHOR]

Cold-formed steel shear walls are commonly used in the housing industry. Generally, the wall stud connections play an important role in the seismic performance of these structures as they should be capable to dissipate the induced energy via the plastic deformation of the shear wall components. The riveted connection between the studs and the tracks is one of the most important components that dictates the behaviour and strength of such panels. In this paper, details of an experimental study on the behaviour and strength of two types of rivets which are applied in riveted wall stud connections under tension and compression monotonic loading are presented. Twenty-four full-scale specimens were taken into account. Two dominant failure modes are identified: rivet head failure and buckling failure of the section away from the connection in tension and compression tests, respectively. The results show that the second rivet type (type O) possesses a higher capacity in both tension and compression; and therefore is recommended to use by CFS designers. In addition, the design capacities of the connections were calculated based on some design codes and compared with the experimental results. It is shown that the codes are too conservative and can be improved considerably. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present finite element modeling protocols and validation studies for the seismic response of a two-story cold-formed steel-framed building with oriented strand board sheathed shear walls. Recently, shake table testing of this building was completed by the authors. The building provides an archetype for modern details of cold-formed steel construction, and provides benchmarks for the seismic response of the building system, subsystem, and components. The seismic response of buildings framed from cold-formed steel has seen little study in comparison with efforts on isolated members and shear walls. Validated building-scale models are needed to expand our understanding of the seismic response of these systems. Finite element models corresponding to the archetype building during its various test phases are developed in OpenSees and detailed herein. For cold-formed steel framed buildings accurate seismic models require consideration of components beyond the isolated shear walls, e.g. the stiffness and capacity of the gravity framing is included in the model. Such decisions require model refinement beyond what is typically performed and details for completing this effort accurately and efficiently are described herein. In addition, nonstructural components, including exterior sheathing of the gravity framing, interior gypsum sheathing for the shear walls and gravity framing, and interior partition walls, are included in the building model based on nonlinear surrogate models that utilize experimental characterization of member-fastener-sheathing response. Comparisons between the developed models and testing for natural period, story drift, accelerations, and foundation hold-down forces validate the model. Performance of the tested archetype building is better than predicted by design or typical engineering assumptions. The model developed herein provides insights into how the building achieves its beneficial performance and will be used to further quantify the lateral resistance of each subsystem and the extent of their coupling. In addition, the protocols used to develop the model herein provide a first examination of the necessary modeling characteristics for wider archetype studies of cold-formed steel-framed buildings and the development and substantiation of seismic response modification coefficients. [ABSTRACT FROM AUTHOR]

This paper presents the probabilistic seismic performance and risk assessment of cold-formed steel (CFS) sheathed shear wall panel (SWP) structures adopting conventional steel moment-resisting frame (MRF) systems as a benchmark with the aim of exploring the viability of using CFS-SWP as a new structural solution in seismic prone regions. A set of 12 building structures of both systems, with 2-, 4- and 5-storey, have been designed for two seismic intensity levels. To simulate their nonlinear behaviour, the structures were modelled adopting recently developed deteriorating hysteresis models. Based on probabilistic seismic hazard analyses (PSHA), a site-specific selection of ground motion records for Incremental Dynamic Analyses (IDA) has been carried out adopting the Conditional Mean Spectrum (CMS) as a more realistic target response spectrum. Subsequently, the seismic risk was evaluated over the structure lifetime ( i.e. , 50 years) in terms of the annual probability of exceeding the Damage Limitation, No-Local Collapse and Near Collapse limit states. The importance and usefulness of the risk metrics are highlighted and adopted as an indicator to explore the behavioural features of both structural systems. Overall, the assessment procedure showed that both systems present an acceptable seismic performance and therefore the CFS-SWP can be seen as a reliable structural solution to achieve performance-based objectives in seismic regions. [ABSTRACT FROM AUTHOR]

• An innovative CFS shear wall with improved lateral load capacity was proposed and studied. • Parametric analysis was conducted to further investigate the fire behavior of the wall. • An optimal sheathing thickness was recommended in this paper. Cold-formed steel center-sheathed shear wall (CFSCSSW) is an innovative shear wall applied to multi-story cold-formed steel buildings. In this study, six tests were carried out on CFSCSSWs, including one room temperature test to obtain load-bearing capacity and five fire tests to investigate the influence of the vertical load ratio, lateral load ratio, interior stud and aspect ratio on the fire behavior of the CFSCSSWs. Subsequently, finite element models were developed to investigate the influence of various combinations of vertical and lateral loads and the sheathing thickness on the fire behavior of the wall. The research results showed that the temperature distribution along the thickness of the wall section is quite non-uniform and the maximum difference reaches 65% from the hot flange to the cold flange. The effect of the vertical load ratio on the fire resistance of the wall is greater than that of the lateral load ratio. The interior stud plays a positive role in improving the fire resistance of the wall. The aspect ratio has little influence on the fire resistance of the wall. The failure model of the wall mainly depends on vertical or lateral loads as well as the aspect ratio. With the increase in the vertical load ratio, the failure location of the wall moves down. Based on the parametric studies, a sheathing thickness of 0.8 mm was recommended for CFSCSSWs. [ABSTRACT FROM AUTHOR]

The seismic deflection amplification factor for a series of archetype buildings utilizing cold-formed steel–framed shear walls was investigated. A total of 118 archetype buildings were considered, of which 83 employed cold-formed steel–framed shear walls with steel sheet sheathing, and 35 employed wood structural panel sheathing. Using nonlinear equivalent single-degree-of-freedom (SDOF) models, nonlinear time-history analyses for the 118 archetype buildings subjected to the 44 FEMA P-695 earthquakes were conducted. In these SDOF models, the actual response of shear walls obtained from experimental studies was used to define the nonlinear material parameters. The AISI S400 deflection expression was evaluated using experimental data, and numerically predicted deflection amplification factors were calculated and compared against that recommended in current practice. The results show that current practice may overestimate expected deflections. To address this issue, and to simplify design, a linearization of the AISI S400 deflection expression is recommended. With appropriate choice of the force level, the linearized AISI S400 deflection expression leads to acceptable drift predictions with the currently employed deflection amplification factor. [ABSTRACT FROM AUTHOR]

The cold-formed steel-framed shear wall sheathed with steel sheet is widely used as a lateral force-resisting system for light-framed construction. However, the boundary conditions of the screw joint are not clear when steel is screwed to the frame. To address this issue, experimental methods have been used to calculate shear strength, but these methods have many limiting factors. In this study, we investigate the structural performance of integrated steel shear walls with varying web width-to-thickness ratios as an alternative to steel-sheathed shear walls used in light-gauge steel frames. The proposed design equation for cold-formed steel integrated shear walls is validated by three specimens and 72 finite element models. This equation allows designers to determine the strength of integrated steel shear walls without conducting full-scale shear-wall tests. [ABSTRACT FROM AUTHOR]

The objective of this paper is to examine the reliability of cold-formed steel framed shear walls with a particular emphasis on walls sheathed with wood structural panels. A sheathed cold-formed steel framed shear wall is a system consisting of studs, tracks, and sheathing often with bridging and/or blocking, connected with steel-to-steel and sheathing-to-steel fasteners. The shear walls may be integrally connected to foundations, floors, or other shear walls through a variety of means including hold downs, straps, diaphragm chords and collectors. Shear wall lateral resistance in cold-formed steel framed buildings varies because of the randomness in the components and connections that comprise the wall. The interaction between fasteners and sheathing is particularly important because (1) sheathing-to-steel fastener response is the main source of shear wall nonlinearity (2) there is high variability in this fastener response. Although the nominal strengths for different shear wall configurations are stated in current design specifications (e.g., AISI S400), variability of shear walls has not been explicitly considered. Existing resistance factors are extrapolations from steel diaphragm testing. To explore the impact of fastener response variability on shear wall reliability, Monte Carlo simulation of typical cold-formed steel framed wood sheathed shear walls with random fastener input was conducted. Variability in fasteners was determined based on existing physical fastener tests. Statistical properties of shear wall strength, demand capacity ratio of key fasteners, as well as relations between fastener strength and shear wall strength are all explored. Reliability evaluation is provided for four different design methods. The results indicate that shear wall strength benefits from a system effect whereby variability in fastener response is reduced through redistribution resulting in reduced variability in overall shear wall strength. Concomitant with this is a slight decrease, approximately 3%, in the mean system strength that also must be considered. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the monotonic and cyclic lateral loading behavior of cold-formed steel (CFS) shear walls sheathed with glued laminated bamboo (glubam ply-bamboo) panels. A total of 16 model shear wall specimens with two types of aspect ratios were tested using ASTM loading protocols. The observed phenomena and the effects of different cyclic loading regimes are discussed. The shear capacity and deformability of ply-bamboo sheathed CFS shear walls are evaluated and compared with wood sheathing panel (WSP) sheathed CFS shear walls through four seismic equivalency parameters recommended by American Iron and Steel Institute (AISI) in 2010 (AISI-RP10-4 2010). The load distribution of the screws along the vertical edges of the panels and the forces in the shear anchors are discussed. The results obtained in this study can further promote the application of bamboo-based material in CFS structures, as potential options for eco-friendly and cost-effective construction. [ABSTRACT FROM AUTHOR]

A seismic design procedure for CFS structures employing sheathed shear wall panels (SWP), compatible with the framework of the Eurocodes, is proposed in this paper. In order to assess the structural behaviour and generate the required data for the appraisal of the seismic design procedure, the OpenSees finite element environment was used to simulate the nonlinear behaviour of CFS-SWP adopting a novel deteriorating hysteresis model. Nonlinear static (pushover) and incremental dynamic analyses (IDA) have been carried out on 54 CFS-SWP frames having 2-, 4- and 5-storeys designed with varying seismic intensity levels. Fragility curves based on buildings collapse probability have been developed following the FEMA P695 methodology. Based on the defined design requirements, the CFS structural system evaluated in this study is shown to meet the acceptance criteria for a behaviour factor ( q ) equal to 2 for low- and moderate-seismicity. Furthermore, the results reveal that the lateral overstrength has a relevant influence on the probability of collapse and that an improved performance could be achieved if continuity of the CFS-SWP chord studs along the height is enforced. [ABSTRACT FROM AUTHOR]

• The feature points of skeleton curve are determined by considering the stress type of bending and shearing respectively. • The skeleton curve and hysteresis loops exhibited stiffness and strength deterioration with pinching effect were determined. • A multi-linear restoring-force model and its calculation flowchart for LEM-infilled CFS shear walls were proposed. Lightweight EPS materials (LEM)-filled cold-formed steel (CFS) shear wall, as a novel-type CFS shear wall, is extensively used in low- and multi-storey rural residences. The previous experiments have revealed that this type of wall appeared significant load-bearing properties and elastic stiffness, and the hysteresis loop appeared obvious stiffness degeneration, slipping and pinching effect. This paper developed a hysteretic model for seismic analysis of these shear walls. Four feature points including elastic, yield, peak and ultimate point are put forward to determine the skeleton curve. Besides, the feature points are determined by considering the stress type of bending and shearing respectively. Through analyzing the typical hysteresis loop, four characteristic points were obtained to express the characteristic of the hysteretic loop. Through the combination of the skeleton curve and hysteretic rule, a multi-linear hysteretic model was established to represent the hysteretic curves. The representative characteristic points of the hysteretic loop were obtained based on test data and the existing literature. The generated skeleton and hysteretic curves were compared with test results and the comparison results showed great agreements in terms of feature points and hysteretic loops. The method would provide a meaningful theoretical basis to assessing the seismic response of the LEM-filled CFS shear wall. [ABSTRACT FROM AUTHOR]

In order to expand the applications of cold-formed thin-walled steel structures, this study proposes a new type of composite wallboard composed of cold-formed thin-walled C-shaped steel and multi-layer concrete, in which C-shaped steel serves as the skeleton, foam concrete acts as the thermal insulation material, and fine aggregate concrete and cement mortar play the part of envelopes. The composite wallboard can be made in a factory assembly line, meeting the requirements of the building (civil and structural) industry. Two steel-frame composite wallboard shear walls were subjected to reciprocating loading, with the connection mode as the design parameter, to investigate the seismic performance of the structure. The failure mode, hysteresis curve, skeleton curve, strength degradation, stiffness degradation, ductility, and energy dissipation capacity of the specimens were analyzed. On this basis, the finite element (FE) model of the steel-frame composite wallboard was established, and the model's accuracy was verified by comparing the bearing capacity and the skeleton curve. Results show that the structure shows shear failure characteristics, and the cement mortar layer and the fine aggregate concrete layer are separated from the C-shaped steel after being crushed. The infilled foam concrete is also crushed, and the welding seams between the extended C-shaped steel and steel frame of the WP-1 specimen are damaged. The hysteresis curves of the two specimens have a clear pinch, but the area enclosed by the hysteresis loop is large, and the energy dissipation capacity is also present. The yield load and ultimate load of the WP-2 specimen are higher than those of the WP-1 specimen, indicating that the higher the connection strength between the composite wallboard and the steel frame, the greater the ultimate carrying capacity of the specimen. The established FE model can accurately estimate the seismic performance of steel-frame composite wallboard shear walls. [ABSTRACT FROM AUTHOR]

Recent research identified the feasibility of adopting corrugated steel sheets as the sheathing material in the cold-formed steel (CFS) shear wall system. However, different experimental results were reported when using different corrugated cross-sections. To determine the effect of different corrugated steel sheathings on the shear capacities of CFS shear walls, this paper conducted an experimental study on the seismic behavior of corrugated steel sheet sheathed shear walls with different cross-section profiles. The selection of corrugated cross-sectional dimensions was informed by the existing research, including corrugated steel sheets with a rib height of 5 mm, 15 mm, and 38 mm. The experiments involved ten full-scale shear wall specimens evaluated under lateral monotonic loading and cyclic loading. The test results indicate that shear walls with 5 mm-rib-height corrugated steel sheets are most likely to produce shear buckling waves, and therefore have the best ductility and highest utilization of sheathing capacity. Shear walls are more apt to screw connection failure and sheathing local buckling as the rib height increases. There is no obvious difference in the shear capacity between the three types of shear walls due to the premature failure of 15 mm- and 38 mm-rib-height corrugated steel sheets. Sheathing buckling was detected and a substantial increase in the shear capacity was achieved when the reduced screw spacing was adopted in the 15 mm-rib-height corrugated sheet sheathed shear walls. The design of corrugated steel sheet sheathed shear walls needs to consider the influence of both the corrugation and screw arrangement. • Monotonic and cyclic loading tests on ten full-scale corrugated steel sheets sheathed CFS shear walls were conducted. • The influence of different cross-section profiles and screw arrangement were studied. • The failure modes, shear capacity, lateral stiffness, ductility, stiffness degradation and energy dissipation capacity of shear walls were analyzed. [ABSTRACT FROM AUTHOR]

• A new type of SPSW structure is proposed. • The mechanical properties and failure modes of the specimens were analysed. • The design method of the shear capacity of buckling-restrained beam-only-connected SPSWs was proposed. In this paper, a new type of steel plate shear wall (SPSW) structure comprising square concrete-filled steel tube (CFST) boundary frame and infilled cold-formed steel (CFS) buckling-restrained beam-only-connected SPSWs is proposed. To study the lateral behaviour and failure modes of the buckling-restrained beam-only-connected SPSWs with square CFST frame, tests on a buckling-restrained beam-only-connected SPSW and a comparison specimen with unstiffened beam-only-connected SPSW with square CFST frame were conducted. The failure mode, hysteretic curve, shear capacity and energy dissipation capacity of the specimens under horizontal cyclic load were reported. The results showed that the two specimens had good lateral resistance and stiffness, which indicated that this structural system was a reliable SPSW structure. Besides, the arrangement of the CFS buckling-restraining strips could improve the seismic performance of beam-only-connected SPSWs. A total of 84 finite element (FE) models were developed and validated. Upon validation, the parametric analysis was carried out, and design method of the shear capacity of buckling-restrained beam-only-connected SPSWs was proposed. The results show that the newly developed design method is accurate and can better predict the yield capacity of CFS buckling-restrained beam-only-connected SPSWs. [ABSTRACT FROM AUTHOR]

This study reviewed some simplified methods of finite element analysis (FEA) for connections in cold-formed steel (CFS) structure, and summarized eight simplified methods divided into three categories. Shear performance tests were performed for six groups of self-piercing riveted (SPR) connection in CFS. A constitutive model of shear behavior for SPR connections was proposed, which was simplified from the load–displacement curve of shear performance test results. The models of SPR connection were established in ABAQUS by the eight simplified methods, and then the FEA results and the test results were compared. The applicable scope of each simplified model was explored, and a simplified method of FEA that was most suitable for the shear behavior of the CFS-SPR connection was proposed. Moreover, the shear performance test of the CFS shear wall with SPR was conducted by considering the rivet spacing, and failure modes and load–deformation curves were obtained. On this basis, numerical models of the CFS-SPR connection shear wall were established. By comparing the test results and the FEA results for the CFS-SPR connection shear wall, the feasibility of a simplified method of FEA applied to the CFS-SPR connection was verified. The main failure modes of the CFS-SPR connection were that the rivet tail pulled out from the bottom sheet and the rivet head pulled over from the top sheet. The SPR connection of the CFS frame could be simplified with a pin or a fastener element, and the SPR connection between the steel frame and the sheathing could be simulated by a Cartesian connector or a Spring2 element. The FEA results were highly similar to the test results for the CFS-SPR shear wall. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of cold formed steel frames sheathed by fibre-cement boards (FCB) under cyclic lateral loading. Four full scale fibre-cement shear walls were tested. Of particular interests are the specimens maximum lateral load capacity and the load–deformation behaviour as well as a rational estimation of the seismic response modification factor, R factor. The study also looks at the failure modes of the systems and investigates the main factors contributing to the ductile response of the CFS shear walls in order to suggest improvements so that the FCB sheathed walls respond plastically with a significant drift and without any risk of brittle failure such as connection failure or fibre-cement board fracture. Both double-sided and single-sided FCB shear panels as well as a new proposed configuration were studied. The study shows that while the overall performance of the currently in-use FCB sheathed lateral resistant system under cyclic loads is not satisfactory with a small average R factor of 2.5, the proposed FCB lateral resistant system can be considered as a reliable system with a much higher value of R factor of 5. [ABSTRACT FROM AUTHOR]

The objective of this paper is to explore and characterize the impact of practical construction details on the cyclic performance of cold-formed steel framed shear walls sheathed with Oriented Strand Board. The specific construction details explored are motivated from a two-story, ledger-framed, cold-formed steel archetype building that is the focus of a larger effort to advance seismic performance-design for light steel frame construction. This larger effort in cold-formed steel (CFS) research is funded primarily by the National Science Foundation / Network for Earthquake Engineering Simulation (NSF/NEES) effort and is known as the CFS/NEES project. The archetype structure is known as the CFS/NEES building. Shear walls in real construction, such as the CFS/NEES building, have details that differ from shear walls tested and provided for strength prediction in standards such as AISI-S213. Key differences include: (a) ledger (rim track) members attached across the interior face of the studs; (b) OSB panel seams, both horizontal and vertical, may not be aligned with the chord studs or only blocked with strap; (c) interior gypsum board is in place; (d) field studs may have a different thickness or grade from the chord studs; and other differences. In this work, these highlighted differences (a-d) are specifically explored in a series of shear wall tests loaded via cyclic (CUREE) protocols to determine their hysteretic performance. The test results are compared with AISI-S213 and hysteretic material characterizations utilizing an elastic-plastic model and a model capable of exhibiting pinching in the hysteretic loops. [ABSTRACT FROM AUTHOR]

The primary objective of this work is to provide connection-level force-deformation response appropriate for standard cold-formed steel (CFS) framed steel sheet sheathed shear walls under cyclic loads. Common CFS framing designs increasingly are exploring thicker framing options so that walls can meet gravity demands, overturning demands, and seismic overstrength requirements. For the seismic performance of self-drilling screw-fastened steel sheet sheathed shear walls, the cyclic nonlinear response of the screw-fastened connection is particularly important and should incorporate the impact of shear buckling of the steel sheet on the strength and ductility of the connection. Minimal cyclic connection-level shear test data exist, especially for combinations of screw-fastened thin steel sheet and thick framing steel. A unique lap shear test following current test standards was proposed to elucidate and characterize the cyclic screw-fastened connection behavior. An asymmetric cyclic loading protocol was selected with a small displacement applied in the direction that buckles the thin steel sheet, followed by progressively larger displacements in the opposite direction. A total of 93 tests were conducted, and characterization of the observed cyclic connection response with a multilinear backbone curve appropriate for use in models is provided. Connection strength is sensitive to whether the thin steel sheet ply is buckling away from or toward the fastener head in some test series. Performance of the screw shear strength as per the standard's provisions is evaluated. The work is intended to provide critical missing information for CFS framed steel sheet sheathed shear walls for use in both simulation and design. [ABSTRACT FROM AUTHOR]

• Cyclic tests of an integral and four spliced prefabricated LEM-filled CFS shear walls were conducted. • FE models of prefabricated LEM-filled CFS shear walls were established and verified by the test results. • A simplified model was proposed to predict the shear bearing capacity of prefabricated shear wall. With the advancement and promotion of green buildings, infilled cold-formed steel (CFS) shear walls have gained considerable attention. In order to promote the assembly degree, novel prefabricated CFS shear walls filled with lightweight expanded polystyrene (EPS) mortars is developed and their corresponding connection method are also developed in this paper. Then, integral prefabricated lightweight EPS mortars (LEM)-filled CFS shear wall and four spliced shear walls assembled using three separated shear walls were designed and tested to evaluate their cyclic performance. The failure patterns, load–displacement relationships, feature values, ductility, stiffness and energy dissipation were systematically analyzed and asserted. The results indicated that prefabricated LEM-filled shear wall appeared superior cyclic performance and spliced shear wall could be used in engineering practice to improve the standardization produce. Subsequently, three-dimensional finite element (FE) models of prefabricated LEM-filled CFS shear walls were established and verified by the experimental data. The FE models considered the initial imperfection of wall studs, nonlinear behavior of the self-drilling screws, and the assembling of separated shear walls. Moreover, the contact stress distributions between the CFS components and LEMs were also analyzed. Finally, a simplified model considering the assembly feature was proposed to predict the shear bearing capacity of the prefabricated shear wall. The exploration illustrated that enhancing the connections between the separated shear walls is an effective measure to guarantee the wall strength. The test and analytical results provide guidance for the application of prefabricated LEM-filled CFS shear walls and promote their development. [ABSTRACT FROM AUTHOR]

Cold-formed steel (CFS) framed construction has been widely adopted and used toward a modern, lightweight, and cost-efficient engineering practice across the United States. The primary objective of this work is to numerically assess the performance of CFS-framed shear walls sheathed with oriented strand board (OSB) and subjected to seismic events. A robust three-dimensional high-fidelity shell finite element model is developed and aims to provide a benchmark modeling approach able to accurately capture strength, stiffness, and failure mechanisms in these systems. Particular attention is given to the fundamental role of the connections between the CFS members and the OSB sheathing to the overall shear wall lateral response. To understand the variability in this critical connection, a series of 30 identical connection tests are performed. The robustness of the proposed computational model is validated by nine different CFS shear wall experimental studies and by a parametric analysis. The developed model is applied to provide an accurate experimentally-derived fastener-based computational tool of CFS-framed shear walls with potential use in design code expansion. [ABSTRACT FROM AUTHOR]

This paper presents the details and application of a newly developed variably oriented spring pair element (VOSPE) model and the Bouc-wen-Baber-Noori (BWBN) constitutive model, to represent the behaviour of the screw connections between the CFS framing and the sheathing in the non-linear finite element analysis of the cold formed steel shear wall panels (CFSSWP) under the monotonic and cyclic loadings. The parameters of the BWBN model were obtained from the experimental load-displacement behaviour of the screw connection data, with the screw experiencing shear parallel to the free edge of the sheathing. The proposed VOSPE screw model was implemented in ABAQUS to analyse the behaviour of cold formed steel wall panels. The finite element analysis results compare well with the experimental results of the overall wall panels under both the monotonic and cyclic loadings, wherein the behaviour and the strength were essentially dictated by the non-linear behaviour and strength of the screw connections. Finally, a non-linear dynamic analysis of a wall panel under an earthquake loading is illustrated, using the proposed model of the wall panel. • A new variably oriented spring pair element (VOSPE) to model screw connection. • Differential Bouc-Wen Baber Noori (BWBN) constitutive model for screw under cyclic loads. • Micro and macro modelling of CFS wall panels. • Nonlinear FEA of CFS wall panels under monotonic and reversed cyclic loading. • Calibration with monotonic and cyclic loading experimental results. [ABSTRACT FROM AUTHOR]

• Seismic response of CFS shear walls with wood sheathing is evaluated following FEMA P695 methodology. • 3-Dimensonal models of two fourteen set of archetypes are developed. • The model of shear walls possesses the ability to simulate nonlinear deteriorating hysteretic behaviour. • A value of 2.5 for behavior factor is proposed for CFS shear walls with wood sheathing. Cold formed steel (CFS) wood sheathed shear walls are one of the most often used type of shear walls applied as the main lateral force resisting system (LFRS) in a lightweight steel (LWS) building. This paper evaluates the behavior factor used in the seismic design according to Eurocodes for buildings equipped with CFS wood sheathed shear walls as the main LFRS. FEMA P695 methodology is used to evaluate the behavior factor. A set of archetypes are selected and designed, which reflected the applicable building heights, seismic hazard and occupancies for LWS buildings in Europe. Nonlinear three-dimensional finite element (FE) models of building archetypes are developed in OpenSees software using the individual shear wall models, which are calibrated on results from tests on individual shear wall specimens. The resilience of building models against collapse is checked by analyzing the models using lateral static (pushover) and incremental dynamic analysis (IDA). Uncertainties arising from test and design information, numerical modelling and archetype response variability to different ground motions is also taken into account. Based on the collapse performance evaluation results, a value of 2.5 for behavior factor, used in the design, is found to provide appropriate level of safety against the collapse in LWS buildings equipped with CFS wood sheathed shear walls. [ABSTRACT FROM AUTHOR]

Cold-formed ultra-thin-walled steel shear wall shows excellent performance. The house constructed using the cold-formed ultra-steel shear wall is composed of continuous single-layer walls, including the floor joints between wall segments. The wall is coordinated to deform through floor joints and the weak part is located at the floor joints. In this paper the test results of nine TCS walls (upper and lower adjacent composite cold-formed ultra-thin-walled steel shear interior wall including floor joints) are reported. The effects of different factors, including axial compression, section height of stud, type of anchor bolt, under cyclic loading on the shear performance of TCS walls are discussed. The results show that, the existence of the axial compression accelerates the screw failure, resulting in reduced bearing capacity. The section height of the wall stud and axial compression of the wall have greater effect on the bearing capacity of TCS wall. Engineers should pay more attention to the influence of wall axial compression. TCS wall experiences progressive damage of multiple components. The degradation of the bearing capacity and stiffness are relatively slow. Cumulative damage is the reason why the TCS wall could not continue to carry loading. For TCS wall with the two nuts on one anchor bolt, screws bear tension-shear action after anchor bolt tilts, and thus the screws and the anchor bolt fail rapidly. After the addition of spatial steel bar truss at the floor joints, the screws only bear the shear force, which improves the wall resistance to damage. • The wall test includes floor joints. The spatial steel bar truss can improve the wall performance. • The inclination of the anchor bolts increases, the screw changes form bearing shear to tension-shear. • The second-order effect makes the wall more prone to the inter-layer damage. • The wall's failure was the result of the cumulative damage. • The test results can provide basic data and qualitative analysis reference for the structure. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of gypsum sheathed cold-formed steel (CFS) shear wall panels under combined action of lateral and gravity loading. The influence of gravity load on the lateral performance of the wall panels is experimentally evaluated through two scenarios of service and design levels. For this purpose, a total of eight full-scale one-side sheathed CFS panels, with two different field screw spacings as well as single and double section chord stud conditions, are considered for the experimental program. Based on the test results, a discussion on different failure modes, load-displacement relationships, maximum shear capacity, maximum displacement at failure, stiffness and energy absorption of the wall panels is presented. The test results are also employed to evaluate the response modification factor (R factor) of the wall panels using two different methods. The results indicate that the wall panels under gravity load at design level can provide higher shear strength, energy absorption and stiffness, but lower ductility compared to wall panels under service gravity load. In addition, the effect of increasing gravity load is more significant when double-section chord is employed for the specimens. The values of the response modification factor also indicate that the method of measuring R factor can relatively affect the results. • The effect of gravity load on the lateral performance of CFS walls sheathed with gypsum board is investigated. • Increasing the gravity load enhances the shear resistance, stiffness and energy absorption of the wall panel. • R factor for panels under service gravity load is higher than walls under gravity load at the design level. [ABSTRACT FROM AUTHOR]