CEE Structures candidate seminar: Development of performance-based seismic retrofit methodology for multi-story buildings
About the event
Recent earthquakes such as Loma Prieta (1989) and Northridge (1994) in California have highlighted the poor performance of existing buildings. Although building codes have clearly evolved, the problem is still unresolved for older buildings that are code-deficient and were designed prior to the implementation of modern seismic design codes. In this seminar, the development and validation of performance-based seismic retrofit (PBSR) methodology is being presented. Unlike traditional force-based design methods, the PBSR method enables engineers to design and retrofit buildings to explicitly meet the pre-defined performance criteria for different levels of earthquake intensity; and eventually, results in a more efficient and comprehensive method of retrofitting multi-story buildings. The proposed PBSR method was validated numerically through multi-incremental dynamic analysis (MIDA), and experimentally by conducting a series of full-scale tests on a four-story 4,000 sqft soft-story wood-frame building at the outdoor shake table at the University of California-San Diego. The test provided the first-of-its-kind (landmark) dataset for use by researchers and practitioners for retrofitting soft-story wood-frame buildings. The experimental test results showed that the retrofitted building met the designated performance criteria and essentially validated the proposed PBSR method. It should be noted that although the PBSR method was only validated experimentally for the asymmetric soft-story wood- frame building, the method can be used for any type of structure with vertical and horizontal irregularities. Finally, in order to investigate the collapse mechanism of soft-story wood-frame buildings, the un-retrofitted building was subjected to series of ground motion with increasing intensities until it collapsed. These series of tests are the first controlled-collapse tests of a full-size building in the U.S.