Development of site class and site coefficient maps of Semarang, Indonesia using field shear wave velocity data

Windu Partono,Sri Prabandiyani Retno Wardani,Masyhur Irsyam,I Iskandar,T.E Agustina,S Ismadji,I Yani,L.N Komariah,S Hasyim

doi:10.1051/matecconf/201710105010

Windu Partono, Sri Prabandiyani Retno Wardani + Show 7 more

Open Access

https://doi.org/10.1051/matecconf/201710105010

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Abstract

The new Indonesian National Code for seismic resistance design (SNI-03-1726-2012) issued recently utilizes seismic response spectra for the whole area of the country. Site class and site coefficient are two parameters needed for designing response spectra. Site class can be estimated using average standard penetration test (N-SPT), average shear wave velocity (Vs) and average un-drained shear strength (Su) of top 30 meter soil deposit. Site coefficients can be predicted using probabilistic seismic hazard analysis (PSHA) by implementing total probability theorem. To perform PSHA, Vs30 is a parameter needed for calculating ground motion at bedrock elevation. This paper presents the results of PSHA and site class analysis using Vs30 values estimated based on N-SPT results collected from 265 boring locations in Semarang. Seismic data in a radius of 500 km from Semarang were collected for PSHA. Site class and site coefficient maps are then developed for the whole study area.

Highlights

Indonesia has implemented the new seismic design code for building and non-building structure SNI-03-17262012
This paper presents the results of site class analysis and probabilistic seismic hazard analysis (PSHA) using real Vs30 values
Site class and site coefficients maps of Semarang were implemented based on the Vs30 values predicted at 265 locations

Summary

Introduction

Indonesia has implemented the new seismic design code for building and non-building structure SNI-03-17262012. Based on [1] site class can be estimated using average standard penetration test (N-SPT), average shear wave velocity (Vs) and average un-drained shear strength (Su) of top 30 meter soil deposit. An average shear wave velocity in the upper 30 meter soil deposit is referred to as Vs30. Site coefficients can be predicted using PSHA by implementing total probability theorem [2]. The shear wave velocity (Vs) for each soil layer for Vs30 calculations is estimated using N-SPT values. Seismic microzonation study of Semarang is still on-going as part of seismic mitigation study following the work conducted by the Team for Revision of Seismic Hazard Maps of Indonesia 2010 (TRSHMI2010)

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