INVESTIGATION OF NATURAL FREQUENCY REDUCTION MECHANISM OF A HISTORIC MASONRY BUILDING IN PATAN FOLLOWING THE 2015 GORKHA EARTHQUAKE IN NEPAL

Abstract

On April 25, 2015, Gorkha earthquake occurred about 80 km northwest of Kathmandu. In Patan, masonry structures collapsed in Durbar Square. The two-story masonry building that is the subject of this study, is about a 5-minute walk from Durbar Square. Although the building did not collapse, cracks were confirmed in several places. Microtremor measurements performed before and after the earthquake revealed that the natural frequencies of the building decreased. This study examined the factors that decrease the natural frequencies of buildings by seismic response analysis using ground motion estimated by the H/V spectrum ratio as input.