Cyclic Performance of Steel Sheet Connections for CFS framed Steel Sheet Sheathed Shear Walls

The main objective of this research is to study fastener-level force-deformation response appropriate for standard cold-formed steel (CFS) framed steel sheet sheathed shear walls under cyclic loads. Recently completed CFS-framed shear wall tests employing thin steel sheets screw-fastened to thicker CFS-framing have recorded higher capacity and ductility for the CFS-framed steel sheet sheathed shear walls. For the seismic performance of these shear walls, the cyclic nonlinear response of the fastener connection is especially important and should incorporate the impact of shear buckling of the steel sheet on the strength and ductility of the connection. Minimal cyclic fastener-level shear test data exists, especially for combinations of screw fastened thin steel sheet and thick framing steel. To address this, a unique lap shear test following AISI S905 was designed to elucidate and characterize the cyclic fastener behavior. The specimens were loaded with an asymmetric cyclic loading protocol which intentionally buckles the sheet in the compression direction, and progressively increases in the tension direction. A total of 93 tests demonstrating a wide range of framing thickness, sheet thickness, fastener size, and loading types were conducted. Key experimental statistics, including the characterization with a multi-linear backbone curve, are provided. Fastener connection strength is sensitive to whether the thin steel sheet ply is buckling away from or towards the fastener head in some test series. AISI S100-16 screw shear strength provisions performance is evaluated. The work is aimed at providing critical missing information for CFS-framed steel sheet sheathed shear walls for use in both simulation and design.This work is part of the research project Seismic Resiliency of Repetitively Framed Mid-Rise Cold-Formed Steel Building (CFS-NHERI) which is supported by the National Science Foundation under Grant No.1663348 and No. 1663569. Test materials were provided by ClarkDietrich and are gratefully acknowledged. The tests conducted herein were assisted by Gbenga Olaolorun and Joel John, the authors would like to express gratitude to their great help. Moreover, the testing would not have been possible without the support from lab staff Nick Logvinovsky, we greatly appreciate his assistance. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the sponsors and employers

Lateral Response of Cold-Formed Steel Framed Steel Sheathed In-line Wall Systems Detailed for Mid-Rise Build

Buildings constructed with cold formed steel (CFS) framing have shown great potential as a modern efficient building system. However, full understanding of their lateral structural behavior, particularly the contribution from non-designated systems, under seismic events is limited. The current North American Standards provide information that can be used to design CFS framed steel sheet shear walls which meet the seismic demands for low- to mid-rise (3-6 story) buildings. However, there is a paucity in experimental data to support design guidelines for taller mid-rise (>6 stories) and high-rise buildings (>10 stories), where large lateral load resistance is required. Moreover, existing code guidelines are based primarily on experiments involving shear walls subject to quasi-static monotonic and reversed cyclic loading protocols. In the current research project, shear walls placed in-line with gravity walls were tested at full-scale first under a sequence of increasing amplitude (in-plane) earthquake motions, and subsequently (for select specimens) under slow monotonic pull conditions to failure. Experiments were performed at the NHERI Large High-Performance Outdoor Shake Table at the University of California, San Diego. The selection of wall details was motivated by a CFS archetype building designed at 4 and 10 stories, as well as available experimental data. This paper documents the experimental response and physical damage observations of four wall specimen pairs in the test program. These particular specimens adopt compression chord stud packs with a steel tension tie-rods assembly, are either unfinished or finished on their exterior face, and laid out in a symmetric or asymmetric fashion. In addition, both Type I and “Type II” shear wall detailing are investigated.The research presented is funded through the National Science Foundation (NSF) grants CMMI 1663569 and CMMI 1663348, project entitled: Collaborative Research: Seismic Resiliency of Repetitively Framed Mid-Rise Cold-Formed Steel Buildings. Ongoing research is a result of collaboration between three academic institutions: University of California, San Diego, Johns Hopkins University and University of Massachusetts Amherst, two institutional granting agencies: American Iron and Steel Institute and Steel Framing Industry Association and ten industry partners. Industry sponsors include ClarkDietrich Building Systems, California Expanded Metal Products Co. (CEMCO), SWS Panel and several others who each provided financial, construction, and materials support. Regarding support for the test program, the efforts of NHERI@UCSD staff, namely, Robert Beckley, Darren McKay, Jeremy Fitcher, and Alex Sherman, and graduate student Filippo Sirotti are greatly appreciated. Findings, opinions, and conclusions are those of the authors and do not necessarily reflect those of the sponsoring organizations

AP205 VLPs based on dimerized capsid proteins accommodate RBM domain of SARS-CoV-2 and serve as an attractive vaccine candidate

COVID-19 is a novel disease caused by SARS-CoV-2 which has conquered the world rapidly resulting in a pandemic that massively impacts our health, social activities, and economy. It is likely that vaccination is the only way to form “herd immunity” and restore the world to normal. Here we developed a vaccine candidate for COVID-19 based on the virus-like particle AP205 displaying the spike receptor binding motif (RBM), which is the major target of neutralizing antibodies in convalescent patients. To this end, we genetically fused the RBM domain of SARS-CoV-2 to the C terminus of AP205 of dimerized capsid proteins. The fused VLPs were expressed in E. coli, which resulted in insoluble aggregates. These aggregates were denatured in 8 M urea followed by refolding, which reconstituted VLP formation as confirmed by electron microscopy analysis. Importantly, immunized mice were able to generate high levels of IgG antibodies recognizing eukaryotically expressed receptor binding domain (RBD) as well as spike protein of SARS-CoV-2. Furthermore, induced antibodies were able to neutralize SARS-CoV-2/ABS/NL20. Additionally, this vaccine candidate has the potential to be produced at large scale for immunization programs

Lateral Response of Cold-Formed Steel Framed Steel Sheathed In-line Wall Systems Detailed for Mid-Rise Build

Buildings constructed with cold formed steel (CFS) framing have shown great potential as a modern efficient building system. However, full understanding of their lateral structural behavior, particularly the contribution from non-designated systems, under seismic events is limited. The current North American Standards provide information that can be used to design CFS framed steel sheet shear walls which meet the seismic demands for low- to mid-rise (3-6 story) buildings. However, there is a paucity in experimental data to support design guidelines for taller mid-rise (>6 stories) and high-rise buildings (>10 stories), where large lateral load resistance is required. Moreover, existing code guidelines are based primarily on experiments involving shear walls subject to quasi-static monotonic and reversed cyclic loading protocols. In the current research project, shear walls placed in-line with gravity walls were tested at full-scale first under a sequence of increasing amplitude (in-plane) earthquake motions, and subsequently (for select specimens) under slow monotonic pull conditions to failure. Experiments were performed at the NHERI Large High-Performance Outdoor Shake Table at the University of California, San Diego. The selection of wall details was motivated by a CFS archetype building designed at 4 and 10 stories, as well as available experimental data. This paper documents the experimental response and physical damage observations of four wall specimen pairs in the test program. These particular specimens adopt compression chord stud packs with a steel tension tie-rods assembly, are either unfinished or finished on their exterior face, and laid out in a symmetric or asymmetric fashion. In addition, both Type I and “Type II” shear wall detailing are investigated.The research presented is funded through the National Science Foundation (NSF) grants CMMI 1663569 and CMMI 1663348, project entitled: Collaborative Research: Seismic Resiliency of Repetitively Framed Mid-Rise Cold-Formed Steel Buildings. Ongoing research is a result of collaboration between three academic institutions: University of California, San Diego, Johns Hopkins University and University of Massachusetts Amherst, two institutional granting agencies: American Iron and Steel Institute and Steel Framing Industry Association and ten industry partners. Industry sponsors include ClarkDietrich Building Systems, California Expanded Metal Products Co. (CEMCO), SWS Panel and several others who each provided financial, construction, and materials support. Regarding support for the test program, the efforts of NHERI@UCSD staff, namely, Robert Beckley, Darren McKay, Jeremy Fitcher, and Alex Sherman, and graduate student Filippo Sirotti are greatly appreciated. Findings, opinions, and conclusions are those of the authors and do not necessarily reflect those of the sponsoring organizations