Seismic Site Characterization and Ground Response Analysis for the Proposed Bridge Site at Prayagraj, India

All important characteristics of ground motion associated with earthquakes can be significantly affected by the local site conditions, such as duration of the seismic shaking, frequency, and peak ground acceleration (PGA). Therefore, it is important to consider the influence of local soil conditions on earthquake resistant design of structures. Seismic site characterization and ground response analysis (GRA) have been carried out for the proposed bridge site over the Yamuna river at Prayagraj, India. Total 22 borehole data have been obtained from each pier location. An empirical correlation between SPT-N number and shear wave velocity (VS) has been developed without geophysical test data using non-linear regression study. The proposed correlation has been compared with existing correlations available for various regions of India. Seismic site characterization has been performed for each borehole location following National Earthquake Hazard Reduction Program (NEHRP) guidelines using 30 m average VS and SPT-N. Further, GRA has been performed for five locations by a one-dimensional equivalent linear approach by using DEEPSOIL software. Spectral acceleration and Fourier amplification ratio have been generated for the surface layer. Significant amplification of the ground motion has been detected in the study site. As a result, the findings would be highly beneficial in generating synthetic ground motions, seismic hazard studies, and retrofitting the existing structures.