Seismic Site Classification of JKR Bridge at Sungai Sepang Using Multichannel Analysis of Surface Wave (MASW)

Abstract

In seismic engineering, the dynamic property of the soil is one of the most important aspects in ground response analysis. Dynamic property is significantly affected by local soil deposits. Shear wave velocity (V s) of soil is one of the main parameters in determining the amplification factor on ground surface. This study aims to determine the shear wave velocity profile of the bridge at Sungai Sepang by using multichannel analysis of surface wave (MASW) method. All the acquired raw data from the MASW field test were analyzed and it can be summarized to three major steps: First, filter the wiggle plot to the analyzable range of frequency of Rayleigh wave; second, develop the dispersion curves of Rayleigh wave phase velocity and; third, inversion of dispersion curve to obtain the V s profiles. The filter and the development of dispersion curve processes were carried out by using Pickwin softwis (SeisImager/SW). Results show that the soil for bridge at Sungai Sepang is having a very low V s30, which is 143.3 and 137.2 m/s, respectively. The soils are classified as Class E which can be considered soft soil according to Uniform Building Code (UBC). Based on the N-SPT value by using empirical formula, the value of V s30 ranges from 101.22 to 151.87 m/s by using different empirical formula. It can be concluded that the value of V s30 for bridge by using MASW is accepted since the value is near to the value of numerical equation from N-SPT value based on borehole data at Sungai Sepang site.