Full-scale testing of soft-story woodframe buildings with stiffness-based retrofits

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 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. This paper summarizes the retrofit and test results for two full-scale buildings that were tested in 2013. The first is a three-story building at the University at Buffalo NEES facility using slow pseudo-dynamic testing. The bottom story, representing a soft story with garage openings, was the numerical substructure and reproduced by computer, while the damage to the two upper stories, representing the physical substructure, was observed in the lab. Then, testing of a full-scale four-story 4,000 sq-ft soft-story building at the UCSD NEES outdoor shake table was conducted. Retrofits ranged from crosslaminated timber rocking walls with rod hold downs to steel special moment frames combined with wood structural panels.

Citation

van de Lindt, J.W.; Bahmani, P.; Jennings, E.N.; Pang, W.; Ziaei, E.; Mochizuki, G.; Gershfeld, M.; Pryor, S.; Shao, X.; Symans, M.; Tian, J.; Rammer, D. 2014. Full-scale testing of a soft-story woodframe building with stiffness-based retrofits. In: Proceedings of the 10th National Conference in Earthquake Engineering. July 21-25, 2014. Anchorage, AK: Earthquake Engineering Research Institute.