NEESR-CR: Steel Truss Systems with Enhanced Seismic Safety and Performance

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This award is an outcome of the NSF 09-524 program solicitation "George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)" competition and includes the University of Texas, Arlington (lead) and Valparaiso University (subaward). This award will utilize the NEES equipment site at the University of Minnesota, named the Multi-Axial Subassemblage Testing (MAST) Laboratory. The goal of this research is to advance seismic safety and design of building structures by studying two steel truss systems: special truss moment frames (STMFs) and staggered truss frames (STFs). Due to their ability to achieve large column-free floor spaces, STMFs and STFs are unique, valuable options for structural engineers. However, although STMFs and STFs offer a wide range of structural, architectural, and economical benefits, limited research data is available on the seismic performance of these systems. Because previous tests on STMFs do not adequately reflect the current practice in design and detailing, substantial improvement in design methodology and confidence could be gained for STMFs by further research. Despite the strong interest among the engineering community, the application of STFs to seismic regions has been restricted due to lack of research. The project will advance knowledge about the system behavior of STMFs and STFs and recommend innovations to improve the seismic performance of these two truss systems.Intellectual Merit: The NEES-MAST facility will be used to impose cyclic loading on large-scale subassemblages that comprise the fundamental structural unit of a STMF or STF. The large-scale tests will be used to: (1) verify the behavior of STMFs constructed according to recommendations from recent research results; (2) explore specific truss configurations that could enhance the performance of STMFs; (3) clarify the system behavior of STFs under cyclic loading; and (4) identify preferred energy dissipation mechanisms for STFs. The structural engineering laboratory at Valparaiso University will be used to examine the cyclic loading performance of shear-stud connections between steel chord members and hollow core concrete planks. In addition, analytical studies will lead to general nonlinear analysis methods that represent the seismic behavior of STMFs and STFs and generate nonlinear time history analysis data for a set of representative building systems that utilize STMFs or STFs. Results from this research will promote wider use of STMFs and STFs.Broader Impacts: This award will support undergraduate students at Valparaiso University and the University of Minnesota to participate in the research. The PI at Valparaiso University participates in an engineering education initiative to introduce scientific visualization using virtual reality systems. These systems will be used to create three-dimensional (3D) models of both the experimental tests and analytical models. The PIs will use the 3D models to aid dissemination of the research results to the professional and academic communities. The 3D models will also be used to develop educational tools to introduce K-12 and undergraduate students to earthquake engineering research activity, the significance of earthquake effects, and the functions of building structures. The educational tools will be made available in the public domain for use in virtual reality systems or with a traditional computer screen projector. Data from this project will be archived and made available to the public through the NEES data repository.