Seismic Response of a Historical Unreinforced Masonry Building Damaged in the 2014 South Napa Earthquake

Several unreinforced masonry buildings damaged during the 2014 South Napa earthquake, California, USA, were investigated after the earthquake. The numerical analyses conducted on a representative example are presented in this paper. The building is the Sam Kee laundry building, the oldest stone commercial building in Napa, built in 1875. The geometry of the building was accurately captured by a laser scanner. Using this geometry information and material data available in literature for similar buildings, a finite element model of the building was developed according to the equivalent frame approach and was subjected to nonlinear time history analyses. The investigated building was closely located to a strong motion station on Main Street, Napa, California. This record was used as seismic excitation input to the numerical model. Results of the conducted analyses accurately predicted the observed damage in the building which consisted of shear cracks and shear damage in the south and north walls and failure of piers from the east wall. Analysis results are used to describe the reasons of the observed damage.