Self-Centering Damage-Free Seismic-Resistant Steel Frame Systems
The project is investigating a family of innovative self-centering (SC) steel frame systems with the potential to withstand the currently accepted design basis earthquake (DBE) for buildings without damage. The project goals are: to develop fundamental knowledge of the seismic behavior of SC steel frame systems; to conduct integrated design, analysis, and experimental research on SC steel frame systems, using the enabling facilities of the George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES); to develop performance-based, reliability-based seismic design procedures and criteria for SC steel frame systems; and to educate students and practitioners with fundamental and practical knowledge about SC steel frame systems.
Unlike conventional earthquake-resistant steel frame systems that are designed to develop significant inelastic deformations under the DBE, resulting in significant damage as well as residual drift, the innovative SC steel frame systems developed by the project have the potential to avoid structural damage under the DBE as a result of several features: the lateral force-drift behavior softens without inelastic deformation of the structural members, and, therefore, without the resulting structural damage and residual drift; the softening behavior is created by gap opening at selected post-tensioned connections (e.g., a separation at the beam-column interfaces of the frame); the ductility capacity of the lateral force-drift behavior can be quite large and is not controlled by material ductility capacity; and energy dissipation under seismic loading is not from damage to main structural members, but from energy dissipation elements that are specified in the design process and can be replaced if damaged.
Both self-centering moment resisting frames (SC-MRFs) and self-centering concentrically-braced frames (SC-CBFs) are being studied with the goals of: (1) developing fundamental knowledge of the seismic behavior of SC-MRF systems and SC-CBF systems, (2) using the research facilities of NEES to conduct integrated design, analysis, and experimental research on SC-MRF and SC-CBF systems, and (3) developing performance-based, reliability-based seismic design procedures and criteria for SC-MRF and SC-CBF systems.
The project scope includes nine research tasks and a number of educational, outreach, and dissemination activities focused on SC steel frame systems. The research team will develop reliability-based seismic design procedures, system concepts and details, and energy dissipation elements for SC steel frame systems; will develop sensor networks to monitor and assess SC steel frame systems; and will design prototype buildings using SC steel frame systems, perform nonlinear analyses of these prototype buildings, and conduct large-scale laboratory simulations on specimens derived from the prototype buildings. The project requires the use of the Real-Time Multidirectional Testing Facility for Seismic Performance Simulation of Large-Scale Structural Systems (RTMD) NEES equipment site at Lehigh for large-scale earthquake simulations to achieve its goals. The hybrid (pseudo-dynamic) testing method will be utilized, and when needed, the real-time hybrid testing method and real-time capabilities of the RTMD will be used as well.
The project team is multi-organizational, involving Lehigh, Princeton, and Purdue Universities, multi-disciplinary and diverse. The team includes international participation from the National Center for Research on Earthquake Engineering (NCREE) in Taiwan, and will be advised by a board of individuals from engineering firms well known in the US and international earthquake and structural engineering communities.