Dynamic Characteristic Investigation of a Historical Masonry Building and Surrounding Ground in Kathmandu

Saving human lives and cultural heritage from natural disasters is a key to earthquake-disaster mitigation strategies. Culturally valued structures built before earthquake codes and regulations emerged are often vulnerable to earthquake loads, but such structures must be comprehensively studied before applying mitigation measures. Microtremor measurements in Patan Durbar Square area, a World Heritage site, were investigated to determine dynamic properties of the soil at four locations and the predominant ground frequency calculated to be 2.07 Hz. Ambient vibration in an old masonry building was measured and vibration frequencies in different modes were detected using the Fourier spectrum, which found that the building has fundamental period in transverse direction. The building’s damping was estimated to be 5.2-6.4%.