Earthquake Ground Motion Parameters for Structural Design in Nepal

Abstract

The study on “Earthquake Ground Motion Parameter for Structural Design in Nepal” is carried out in two parts: in the first part, the probabilistic seismic hazard analysis is carried out for the Kathmandu Valley considering 10-active faults as earthquake sources; the recurrence law proposed by Gutenberg-Richter is used. The intensity of earthquake at the center of Kathmandu valley in terms of PGA and SA is obtained by adopting the attenuation law proposed by Youngs et al (1997) and poison’s process for occurrence of earthquakes. Using conditional probability of magnitude of earthquake and source to site distance, the probabilistic seismic hazard curves are obtain at the bed rock, free field as well as separately assuming soil amplification factor of 2. In the second part of the study, a single envelope of the spectral ordinates are obtained using Young’s et al empirical relationship due to all sources for bed rock and free field separately, which are used to simulate Time-Histories at the bed rock as well at free field . The study shows that the contribution of Source Gosai Kunda (MCT-3.30) in Seismic Hazard curves is larger compare to the other sources and it is considered to be the vulnerable source for Kathmandu City. The program developed in Visual Fortran which generates time history from response spectra and gives good result within 20 iterations. Results are verified using Standard Software (SeismoSignal).