CFSRC Colloquium 2022


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    Proceedings and Summary of the 2022 CFSRC Colloquium
    (2022-10-19) Schafer, B.W.; Ayhan, D.
    With 125 concurrent attendees from over 10 time zones and 65 papers and talks the second edition of the global online Colloquium held from 17-19 October 2022 kept providing a unique forum for sharing and learning about the latest research and innovations in cold-formed steel structures. The Cold-Formed Steel Research Consortium (CFSRC) hosted the Colloquium which was delivered in five main sessions on Zoom with concurrent conversations, messaging, and a central blog in a dedicated Slack site. Attendees were able to listen and see the latest research, click through on the program to the accompanying paper, and contribute in real time to the ongoing conversations about the work being presented. CFSRC Director Ben Schafer provided a consistent online conversation throughout the Colloquium. The Colloquium was sponsored by: he American Iron and Steel Institute (AISI), Clark Dietrich, the Metal Building Manufacturers Association(MBMA), RSG Software, Run To Solve Inc., the Steel Deck Institute, Unarco Material Handling, United States Steel Corporation and Verco Decking. The participation of the sponsors not only demonstrated their commitment to innovation in cold-formed steel structures it also enabled a series of awards to be made to the next generation of of cold-formed steel researches through student awards for both best paper and best presentation. Liang Chen, PhD Student, The Hong Kong Polytechnic University, Hong Kong won the best paper award in 'Modeling Insights' for his paper “Numerical Implementation of GMNIA for Steel Frame with Nonsymmetric Sections”. Fu-Wei Wu, PhD Student, Department of Structural Engineering, Tongji University won honorable mention for his paper “Seismic Performance Evaluation of Steel-sheathed Cold-formed Steel Trussed Shear Walls”. Duy Khanh Pham, PhD Student, School of Civil Engineering, University of Sydney won the best paper award in 'Experimental Insights' for his paper “The Use of Average Bending Moments in New Explicit DSM for Bending-Shear Interaction in Cold- formed Steel Channels”. Chu Ding, graduate student, Department of Civil & System Engineering, Johns Hopkins University won honorable mention for his paper “Structural Behavior Of Advanced High Strength Steel: Ductility, Connections, Members”. Astrid Winther Fischer, Postdoctoral Fellow, Department of Civil & System Engineering, Johns Hopkins University won the best paper award in 'Innovation and Creativity' for her paper “Non-linear performance of topology optimized orthotropic bare steel deck diaphragms”. Xia Yan, graduate student, Department of Civil & System Engineering, Johns Hopkins University won honorable mention for his paper “Performance-based fire design applied to the cold-formed steel end walls of a warehouse metal building”. Andrea Rajić, Research Assistant, Structural Engineering Department, Faculty of Civil Engineering, University of Zagreb won the best presentation award for her work on “Numerical study of cold-formed steel-concrete composite floor system with demountable shear connectors”. The awards committee provided two honorable mention awards for best presentation, including: Victoria Ding, Graduate Research Assistant, Department of Civil & System Engineering, Johns Hopkins University, for her work on “Experimental Tests on Stability of Cylindrical Shells Under Combined Bending and Torsion”; and Ghaith Alshamsi, PhD candidate, Department of Civil & Environmental Engineering, University of Waterloo for his work on “Experimental & Numerical Investigation of an Innovative, High Capacity Cold-Formed Steel Shear Wall”. The 65 papers in the Colloquium program are all publicly accessible through a permanent host from the Sheridan Libraries at Johns Hopkins University. Each paper represents a unique contribution to our knowledge of the behavior, performance, and design of cold-formed steel structures. Papers addressed all aspects of the performance of cold-formed steel structures. Notable in the collection is a large number of papers addressing fire performance and analysis, and earthquake engineering of cold-formed steel as well as papers addressing the fundamental stability of thin-walled cold-formed steel members, systems and applications. The Colloquium was organized by Dr. Deniz Ayhan (CFSRC Scholar), Dr. Hannah Blum (CFSRC Affiliated Investigator), Dr. Kara Peterman (CFSRC Affiliated Investigator), Dr. Zhanjie Li (CFSRC Affiliated Investigator), Dr. Cheng Yu (CFSRC Investigator) and Dr. Ben Schafer (CFSRC Director). CFSRC brings together researchers and facilities across institutions in North America to form the premiere organization in the world devoted to comprehensive, innovative, and impactful research to advance the design of cold-formed steel structures.
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    Structural Behavior Of Advanced High Strength Steel: Ductility, Connections, Members
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Ding, Chu; Xia, Yu; Akchurin, Damir; Blum, Hannah B.; Li, Zhanjie; Schafer, Benjamin W.
    This paper summarizes recently completed experimental and numerical research on the structural behavior of advanced high strength steel (AHSS) structural components conducted at the authors’ institutions. For material ductility, tensile coupon tests were completed to establish a database of the stress-strain curves for these new materials and also to develop quantifications of their ductility. The research on connections focuses on the strength of four cold-formed steel (CFS) connection limit states: tension rupture, bearing, tilting/bearing, and end tear-out. The relationship between connection strengths and material ductility is investigated to further the understanding of ductility demand in CFS connections. Research on AHSS structural members includes columns in pure compression and beam in major axis bending. Analysis of the member experiment and finite element simulation results lead to proposed improvements for the Direct Strength Method (DSM) in members with high slenderness and/or high mode interaction potential. Overall, the study reported in this paper improves the understanding of ductility’s influence in structural connection design and extends the applicability of the current CFS buckling design method for high slenderness members, all of which make necessary preparations for introducing this new type of high-strength steel, AHSS, into cold-formed steel design specifications and more broadly in building construction.
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    The behavior of cold-formed steel and Belian hardwood self-tapping screw connections
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10) Adeline, Ng L.Y.; Lau, H.H.; Fang, Z.; Roy, K.; Gary, R.M.; Lim, J.
    Cold-formed steel has been widely used to retrofit and restore buildings, especially timber buildings. This is because the material is readily available, flexible, and lightweight. However, limited research is available with little assessment concerning cold-formed steel and hardwood connection performance. This paper experimentally studies the behavior of connections composed of self-tapping screws, cold-formed steel, and Belian hardwood. Five connection configurations were investigated, where the ultimate load-carrying capacity of the connection was determined through a sequence of shear and tension tests. The results showed that the connection failed by screw withdrawal under tension load. However, when loaded in shear, the failure mode of the connection changed from screw failure when the screw head was at the Belian side to screw rotation when the screw head was at the cold-formed steel side. The performance of current design guidance in Eurocode 5 was assessed by comparing the strengths obtained from the experiments. The comparison results showed that Eurocode 5 is conservative in predicting the performance of self-tapping screw connection composed of cold-formed steel and Belian hardwood in tension. However, it was overly conservative in predicting the shear strength of the connection as the design strengths are overestimated by around 60%.
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    Numerical studies on the shift of centroid in cold-formed steel members due to local-plate and distortional buckling
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Abdulnour, Elie; Kövesdi, Balázs; Ádány, Sándor
    In thin-walled members subjected to compressive actions the stress distribution is changing as local-plate buckling develops. This phenomenon is the background of the Effective Width Method, which is widely used in various design standards, including those for cold-formed steel structures. Due to stress redistribution, the position of the stress resultant typically changes, too, which phenomenon is identified as shift of effective centroid. It can be supposed, however, that redistribution exists if the buckling is distortional, which is potentially associated with shift of centroid, too. In the reported research numerical studies have been conducted by using nonlinear shell finite element models, aiming to numerically determine the shift of centroid, separately to local-plate and to distortional buckling, for channel section columns. The results confirm that shift of centroid is possible due to distortional buckling, but in the case of typical sections the shift due to distortional buckling is small compared to that due to local-plate buckling.
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    Experimental & Numerical Investigation of an Innovative, High Capacity Cold-Formed Steel Shear Wall
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Alshamsi, Ghaith; Xu, Lei; Shi, Yu; Yao, Xinmei; Zou, Yuxuan
    The study presented herein is concerned with establishing benchmark finite element models of high capacity cold-formed steel (CFS) shear walls. CFS shear walls have emerged as an economic and light-weight seismic force resisting system (SFRS), unfortunately their applications are limited to low- and mid-rise residential and commercial buildings. To advance the state-of-the art, a preliminary, full-scale testing program of an innovative, higher-capacity CFS shear wall is conducted. The shear wall configuration consists of a thin steel sheathing concentrically confined between built-up hat section wall studs and built-up, L-shaped tracks. Furthermore, the testing program includes monotonic and cyclic tests of the walls, as well as screw connection assembly tests in double shear. In addition, finite element models of the shear walls were developed via the software ABAQUS and calibrated with the experimental results. To overcome convergence issues, the explicit solver was employed, and a linear kinematic hardening user-defined material model (VUMAT) was used. Finally, to assess the behavior and structural efficiency of the wall, numerous parametric studies were carried out. Several construction details were assessed, including height-to-width aspect ratio, spacing of screws, thickness of the framing members and end conditions of the wall assembly. The results indicate that the shear wall configuration discussed in this paper can reach capacities that are two times more than conventional CFS shear walls that are stipulated in current AISI S400 standard.
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    An Experimental and Analytical Study on Cold Formed Steel Floor Trusses with Bare and Concrete Filled Compression Chords
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Dizdar, Cagan; Guldur, Hazal; Baran, Eray; Topkaya, Cem
    Floor trusses fabricated from cold-formed steel (CFS) sections are commonly preferred for floor system construction in CFS buildings in certain parts of the world. An integrated experimental and numerical study has been conducted to investigate the behavior of such trusses. The investigation included both bare CFS trusses, as well as trusses with the top chord members filled with concrete in an attempt to eliminate compression buckling. Bare steel truss tests included seventeen full-scale trusses with the major test variables of CFS section thickness, type of diagonal-to-chord connection, and number of connection fasteners. Test results have shown that the analytically calculated and measured responses differ in terms of truss stiffness. Measured stiffness of the trusses within the service load level came out to be lower than the stiffness obtained using two dimensional analytical models. Hence, additional experiments on screw connections were conducted and by these results analytical expressions were developed to simulate connection flexibility. An additional five truss specimens were tested as part of the investigation on steel-concrete composite trusses. Test results indicate that the presence of concrete infill inside the compression chord member prevents the initiation of chord local/distortional buckling and provides significant improvement in truss response in terms of increase in stiffness and load capacity.
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    Numerical study of cold-formed steel-concrete composite floor system with demountable shear connectors
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Rajić, Andrea; Lukačević, Ivan; Ćurković, Ivan; Žuvelek, Vlaho
    Except for the main advantage of the composite systems, which is the efficient utilisation of used materials, these structural systems are known for reusability, high degree of prefabrication and long-span capability. Because of these advantages, the range of applications of composite structures is continuously expanded. Since cold-formed steel sections have many benefits compared to hot-rolled sections, their implementation in composite systems has become more attractive to researchers in recent years. This paper represents numerical research on the bending behaviour of composite cold-formed steel-concrete beams. Spot-welding technology for connecting cold-formed steel elements and innovative demountable shear connections with bolts were used as a part of the LWT-FLOOR project at the Faculty of Civil Engineering, University of Zagreb, Croatia. Cold-formed steel elements are built-up beams with back-to-back profiles as flanges and corrugated webs. The obtained results provide the basis for implementing laboratory research on the proposed system. Experimental results of tensile base materials and spot welds behaviour were used to support numerical research. Numerical analyses were conducted in Abaqus/CAE, where the influence of the degree of shear connection, spot weld density, concrete type, steel cross-section thickness and the diameter of the shear connector were analysed. The performed analyses showed that the influence of the degree of shear connection and spot weld density have a significant impact on system behaviour. The influence of concrete type is negligible when comparing the models with the same spot weld density and full shear connection. The same influence becomes greater for models with the partial shear connection. In addition, results show that the thicknesses of the corrugated web and C profile highly influence the bending resistance of the analysed system. Corrugated web thickness results in the highest flexural stiffness and bending resistance in the case of tied steel elements. Furthermore, for steel beam elements connected by spot welds, the corrugated web thickness had a more significant influence on the beam resistance. Regarding the diameter of the shear connector, it is concluded that it has a negligible influence on the bending resistance of the analysed system due to the crushing of concrete for both diameters.
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    Numerical study of the behavior of the bolted shear connection in cold-formed steel-concrete composite beam
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Žuvelek, Vlaho; Ćurković, Ivan; Lukačević, Ivan; Rajić, Andrea
    Nowadays, composite steel-concrete systems are among the most cost-effective construction systems for application in multi-storey buildings as they combine structural efficiency and allow accelerated construction speed. Additional optimisation of these systems is possible through the application of cold-formed steel elements and innovative solutions for shear connections. Such optimisation of composite systems is the topic of the LWT-FLOOR project ongoing at the Faculty of Civil Engineering in Zagreb. This paper presents a numerical study of two various cold-formed steel beam types connected to a concrete slab placed within profiled steel sheeting and interconnected using the bolted shear connection. The first cold-formed steel beam type consists of built-up sections using back-to-back cold-formed steel C profiles, while the second type additionally uses a corrugated web inserted between the webs of the cold-formed steel C profiles. To evaluate shear connection behaviour, simulations of the push-out test are performed where either solution with two bolts per rib placed symmetrically or the solution with one bolt per rib placed in a staggered manner is used. Compared to the shear connection with two bolts per rib it is expected that staggered bolt placement would have much less influence on the shear connection strength in the case of cold-formed steel profiles without corrugated web than in the case when the corrugated web is used. Furthermore, a previous study on the behaviour of bolted shear connection in composite systems using cold-formed steel profiles indicates that the proposed values of the reduction factor, 𝑘𝑡 when profiled steel sheeting ribs are placed transverse to the steel beam may be too conservative or, in some cases, even completely unnecessary. Therefore, a numerical study on the composite system using cold-formed steel profiles and the corrugated web was further expanded to evaluate the influence of different parameters on the value of the reduction factor.
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    Block Shear Strength and Structural Behaviour of Cold-Formed Steel Staggered Hole Bolted Connections
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Pham, Viet Binh; Pham, Cao Hung; Hancock, Gregory J
    Research on the structural behaviour of cold-formed steel staggered hole bolted connections failing in block shear with a combination of tension and inclined shear behaviour is investigated in this paper. An experimental program and finite element model (FEM) simulation of the block shear behaviour were established to provide a better understanding of the failure modes particularly in the staggered zones. The angle of the staggered holes not only changes the location of the fracture paths in the staggered zones but also affects the nominal block shear strength of the connections. In particular, the whole strength in the staggered zones includes two components (i.e., the shear strength on failure paths parallel to the staggered path and the tension strength on the segments perpendicular to the staggered path) caused by the combination of the shear yielding and tension rupture. Consequently, a new design formula for determining the block shear strength of staggered hole bolted connections is proposed based on the mechanical behaviour. The proposed formula provides better agreement with both the test results and FEM simulations in comparison with the current design specifications and standards namely AISI S100:2016 and AS/NZS 4600:2018. In terms of the experimental program, specimens using G450 sheet to AS 1397-2011 were tested with 1.9mm and 2.4mm thicknesses. A calibrated finite element model was then verified against the test results to obtain reliable data for use in the verification procedure of the proposed formula.
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    Yield Models for use in DSM Localised Loading Design of Hat Sections
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Chen, Zhehang; Pham, Cao Hung; Hancock, Gregory J.
    The direct strength method (DSM) of design is a newly developed method for the design of cold-formed steel members. It has been well developed and incorporated into the North American Specification AISI S100 and the Australian/New Zealand Standard AS/NZS 4600 for cold-formed steel sections under compression, bending and shear. Recently, a consistent and simplified DSM for the design of cold-formed steel structural members under localized loading has been developed for single web sections such as channels and zeds and was published in the literature. However, there are no methods available for multiple web sections such as hat sections and decking. The mechanical behaviour of multiple web sections is not yet fully understood and there have been to date few publications, discussing the mechanical behaviour of hat sections under localised loading. This paper proposes and explains a yield model in determining the yield load (Py) for use in the DSM for localized loading design of hat sections. It has to be taken in conjunction with the elastic buckling load Pcr described separately. A series of equations is developed to calculate Py for both vertical-web and sloping-web sections. A detailed discussion on the different models of the yield load (Py) is also included.
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    The Use of Average Bending Moments in New Explicit DSM for Bending-Shear Interaction in Cold- formed Steel Channels
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Pham, Duy Khanh; Pham, Cao Hung; Hancock, Gregory J.
    The current Direct Strength Method (DSM) for the design of cold-formed steel sections under combined bending and shear in Specifications/Standards (AISI S100 and AS/NZS 4600) is based on the traditional bending-shear interaction curves for both elastic local buckling and post-buckling capacities. Specifically, the current design check is conducted indirectly using normalized ratios of the design actions of Maximum Bending and Maximum Shear to the corresponding buckling strengths of the members under pure bending and pure shear. This is an implicit design method and overestimates the local buckling strengths of sections governed by bending-shear interaction. By the use of an Average Bending Moment, a new explicit design approach in line with DSM curves is developed for ultimate strengths of cold-formed sections under different combinations of bending and shear. This concept comes from the interaction between shear and average bending moment rather than maximum bending moment, and gives accurate predictions for ultimate strengths, which can replace the use of traditional normalized design load-strength ratios. In addition, a combination of the new DSM curve for average bending moment and the current DSM curve for shear is also presented to provide strength prediction for the full range of bending- shear combinations. The full approach is validated using a series of reliable testing data from the literature. Recommendations for practical design in the use of the new explicit method are also included in this paper.
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    Non-linear performance of topology optimized orthotropic bare steel deck diaphragms
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Fischer, Astrid Winther; Ferrari, Federico; Guest, James K.; Schafer, Benjamin W.
    The objective of this paper is to compare the elasto-plastic response of traditional and optimized roof diaphragm designs under lateral loads. The seismic building design depends on the floor and roof diaphragms can transfer lateral loads to the vertical lateral force resisting systems and ensure continued global stability of the structure during seismic events. Diaphragms have traditionally been designed to remain elastic, but researchers have observed that diaphragms experience inelastic deformations in earthquakes. Work in a recent paper used topology optimization to design bare steel deck diaphragms by optimizing the deck selection and deck orientations assuming linear elastic behavior. The optimized designs as well as traditional designed diaphragms are subjected to a non-linear pushover analysis assuming the deck plasticization is solely governed by shear deformations and reduction in shear stiffness. It was found that the optimized designs outperform typical deck designs in terms of ultimate bearing capacity and energy dissipation despite being optimized with respect to linear stiffness alone. It is hoped that these findings will encourage further research into the design of diaphragm decks that are both stiffer and more stable under plastic deformations. This work is part of a larger initiative ( that aims to better understand and optimize the role of diaphragms in the seismic response of steel buildings.
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    Structural Design Narrative of the CFS-NHERI 10-story Test Building for Multi-dimensional Shake Table Testing
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Singh, A.; Hutchinson, T.C.; Torabian, S.; Schafer, B.W.; Peterman, K.D.; Padgett, L.; Jones, H.
    Cold-formed steel (CFS) framing is a popular choice for construction of low to mid-rise structures because it provides significant cost benefits through use of prefabricated assemblies and produces lightweight structures with high durability and ductility. It is manufactured from recycled materials, exhibits consistent material behavior offering a high strength-to- weight ratio and is resistant to corrosion. Benefits of CFS framing align well with the system resiliency needs in moderate to high seismic zones from a performance perspective. However, the use of CFS framing for construction of mid to high- rise structures in the North American construction industry is severely restricted due to a lack of available full-scale system level test data documenting both earthquake and post-earthquake fire response of CFS-framed buildings. To address this issue, a 10-story CFS-framed building, herein referred to as the CFS-NHERI test building, is planned to be tested under increasing earthquake motion intensity, and subsequently subjected to live fire testing, at the NHERI 6-DOF Large High-Performance Outdoor Shake Table (LHPOST6) facility at University of California, San Diego. This paper documents the structural design and detailing decisions adopted for the gravity and lateral force resisting systems of the CFS-NHERI test building, which will have a floor plan of 11.0 m×6.9 m (36 ft×22.5 ft) and consistent 3.05 m (10 ft) story height. This building will also be the first to integrate architectural finishes and will have a 30.5 m (100 ft) building height which exceeds the height limitations set by the ASCE 7 design standards.
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    Structural Analysis in Virtual Reality for Education with BMLY
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Zhang, Lanyi; Moen, Cristopher D.; Blum, Hannah B.; Marks, Benjy
    Virtual reality (VR) is an engaging and immersive medium for interacting with a digital environment. The educational benefits of implementing virtual reality into learning modules has recently been explored. This work presents a process for creating a virtual reality learning module on beam bending and a preliminary study on its effectiveness. In this work, virtual reality and structural analysis are combined to create an interactive virtual experiment on a steel beam. A VR user can select the location of a gravity load along the member and increase its magnitude while following the deformation and stresses in real time. The VR environment is implemented using the open source three.js library. The results of a survey to assess student interaction and evaluation of the developed learning module is presented.
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    Analysis of roof live loads in industrial buildings
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Karasu, Adem; Peterman, Kara D.; Arwade, Sanjay R.
    In design, structural engineers must have a clear understanding of live loads, both qualitatively and statistically. For decades, multiple studies have been published that relate live loads for floor loads in various occupancies such as offices and residences. However, survey data or probabilistic live load models for industrial building roofs are difficult to find. There are recommendations in major standards used in the modern world that give design live load values for roofs based on the accessibility of the rooftops. On the other hand, engineers may not understand the origin of these values. Comparison is made between current U.S standards for roof live loads and standards used in other parts of the world. To ensure that the most accurate live load assessment is implemented in the design, our understanding of live loads should be updated on a regular basis. Furthermore, in the United States, the current roof live load design value is 0.96 kN/m2 (20 psf), which is much greater than the values recommended by European, Australian, and Chinese standards. As a result, determining the source of live load on industrial building roofs is essential. To cover the gap in the literature, this article gives survey methodology and probabilistic studies related to design live load value on roofs. The sensitivity of existing probabilistic models to mean, variance, and time duration was also investigated.
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    An open-source cold-formed steel connection test database to support future data models
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Moen, Cristopher D.; Chen, Baihan
    A data structure and physical test database are implemented for cold-formed steel connections. The database is publicly available on GitHub in a format that is both human-readable and machine-readable. The data structure is designed to accommodate connection tests with varying test variables including fastener type, quantity of fasteners in a specimen, and the number and type of plies. The database design is made compatible with open-source software tooling to support future data-driven model development. Strategies are discussed for encouraging general user adoption of open-source databases and software including education, community guidelines, and easy-to-use interfaces.
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    Incompetence of current fire standard to predict design reduction factors for cold-formed steels
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Kumar, Waibhaw; Sharma, Umesh Kumar
    The paper investigates the competence of current fire standards in predicting the design reduction factors for cold-formed structural steel. Toward this end, the design reduction factors of cold-formed structural steel having various grades were compared with that predicted by EC3, AISC, IS 800, BS,5950 and AS 4100. Most of the available reduction factors at elevated temperatures reported in the above-mentioned codes were best suited for hot-rolled steels and leave a huge void for cold-formed steels. Further, the design of cold-formed structural steel members using above standards results in unsafe design. This paper gives a solution for estimation for strength and stiffness reduction factors that leads to safe design.
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    Seismic Analysis of the 10-Story CFS-NHERI Building
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Zhang, Jiachen; Singh, Amanpreet; Hutchinson, Tara C.; Wang, Xiang
    A 10-story full-scale cold-formed steel building is scheduled to be tested on the newly upgraded 6-DOF Large High- Performance Outdoor Shake Table (LHPOST6) at the University of California San Diego serving as the capstone effort to the NSF-funded Collaborative Research: Seismic Resiliency of Repetitively Framed Mid-Rise Cold-Formed Steel Build- ings (CFS-NHERI) project. In preparation for this test program, a simplified pancake model is developed in OpenSees to predict the dynamic characteristics and to simulate the behavior of this 10-story test building under nonlinear dynamic re- sponse history analysis. The pancake model is composed of rigid diaphragms and nonlinear shear springs representing the hysteretic behavior of the lateral load resisting shear walls. Pinching4 material properties calibrated using past experiments defined the properties of shear springs with scaling based on geometric properties. To evaluate the robustness of the ap- proach, a similar model of a 6-story CFS building, tested under uni-directional shaking was also developed. For the 6-story modeling effort, the dynamic characteristics and response under the same series of ground motions used in the shake table tests are compared with the test results and good agreement is observed. Thus, for the 10-story CFS-NHERI building (pre- test) analyses, a suite of 22 far-field ground motion pairs provided in FEMA P695 are chosen to perform nonlinear response history analysis. The responses under these scaled ground motions are compared to investigate the effect on the seismic response of the 10-story CFS-NHERI building. In future work, the responses of the pancake model will be compared with other numerical models being developed by fellow researchers within the CFS-NHERI team using more complex wall line representations for example. At present however, it is recognized that the simplified pancake model provides a fast compu- tational turnaround time, while effectively capturing the characteristics and providing reasonable estimates of the responses, which makes it useful for pre-test analyses to identify a candidate suite of ground motions to be used for the future shake table test program.
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    Behavior and Strength of Cold-Formed Steel Framed Shear Walls Sheathed by MgO Board
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Yu, Cheng; Yelmagandla, Hruthik; Gondipalli, Hemanth
    MgO board is made from magnesium oxide which is a type of mineral cement and contains magnesium and oxygen. MgO panels are like drywall or cement board, but with much-improved characteristics such as fire resistance, weather ability, strength, resistance to mold and mildew, and so on. MgO board reinforced with layers of glass fiber mesh could be a non- combustible sheathing material for shear walls and floor/roof diaphragms. This paper presents an experimental program recently performed in the Cold-Formed Steel Research Center at the University of North Texas. The research goal is to study the behavior and obtain the shear strength of cold-formed steel framed shear walls sheathed by 1⁄2” MgO boards. Both monotonic and cyclic shear wall tests were performed. Two different screw spacings on the panel edges were considered. Screws shear failures and sheathing ruptures were observed in the tests. Nominal shear strength for wind and seismic loads was established to support the engineering design of MgO board sheathed cold-formed steel frame shear walls.
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    Determination of Geometric Imperfections via 3D Data Processing
    (Cold-Formed Steel Research Consortium (CFSRC) Colloquium, 2022-10-17) Güldür Erkal, Burcu; Cagrici, Ozge G.
    The individual behavior of cold-formed steel (CFS) members is affected by geometric imperfections. Therefore, it is necessary to correctly identify and quantify present geometric imperfections to predict CFS member behavior under various loading conditions. In this paper, 3D optical scanners are used to capture the C-sectioned CFS members' as-is conditions. The 3D representations captured by the optical scanners are then used to extract geometric imperfection information. An automated methodology is developed for geometric imperfection detection and quantification. The developed method is then tested on 16 C-sectioned CFS members to obtain geometric imperfection information.