Full-scale Dynamic Testing of Soft-Story Retrofitted and Un-Retrofitted Woodframe Buildings

Abstract

The existence of thousands of soft-story woodframe buildings in California has been recognized as a disaster preparedness problem with concerted mitigation efforts underway in many cities throughout the state. The vast majority of those efforts are based on numerical modeling, often with half-century old data in which assumptions have to be made based on best engineering judgment and project committee consensus. The NEES-Soft project, whose full title is “Seismic Risk Reduction for Soft-Story Woodframe Buildings,” is a five university multi-industry three-year project which has many facets including improved nonlinear numerical modeling, outreach, design method development, and full-scale system level experimental validation of soft-story retrofit techniques. In 2013, two full-scale buildings will be tested within NEES-Soft. The first is a three-story building which will be tested at the University at Buffalo NEES facility using slow pseudo-dynamic testing. The bottom story, representing a soft story with garage openings, will be the numerical substructure and reproduced by computer, while the damage to the two upper stories, representing the physical substructure, will be observed in the lab and provide feedback to the actuators. This test has the main objective of determining the effect of the retrofits on damage to the upper stories and collapse risk of the complete structure. The second major test, to be conducted in the summer of 2013, is on a full-scale four-story 4,000 sq-ft soft-story building. It will be tested by the NEESSoft project team at the UCSD NEES outdoor shake table using a variety of retrofits. These retrofits will range from FEMA P-807 retrofits to performance-based seismic retrofits developed as part of the project. Full-scale test results for both full-scale system specimens will be presented and comparisons made to the FEMA P-807 performance expectation and the performance-based seismic retrofit.

Citation

Lindt, John W. van de; Abell, George T.; Bahmani, Pouria; Gershfeld, Mikhail; Shao, Xiaoyun; Pang, Weichiang; Symans, Michael D.; Ziaei, Ershad; Pryor, Steven E.; Rammer, Douglas; Tian, Jingjing. 2013. Full-scale Dynamic Testing of Soft-Story Retrofitted and Un-Retrofitted Woodframe Buildings. In: Proceedings, Structural Engineers Association of California Convention, September 18-21, 2013, San Diego, California; 2013; pp. 219-228.