Proceedings of the 6 th Asia-Pacific Structural Engineering and Construction Conference (APSEC 2006), 5 – 6 September 2006, Kuala Lumpur, Malaysia E-34 DEVELOPMENT OF SYNTHETIC TIME HISTORIES AT BEDROCK FOR KUALA LUMPUR Azlan Adnan 1 , Hendriyawan 2 , Aminaton Marto 3 , Masyhur Irsyam 4 Structural Earthquake Engineering Research Faculty of Civil Engineering-Universiti Teknologi Malaysia Structure and Material Laboratory D-04, Tel. 07 5531748 azlan@seer.org.my 1 ; hendri@seer.org.my 2 ABSTRACT: Acceleration Time-histories of earthquake ground motions are required for analyzing the structural performances and response of soil deposits under seismic loading. Selection of appropriate time-histories for specific geological and seismological conditions plays an important role for obtaining accurate results. Due to lack of representative strong motion data recorded in Malaysia, synthetic ground motions were generated in the frequency domain by using spectral matching analysis and random vibration theory. The uniform hazard spectra (UHS), which are required for developing synthetic time histories, were obtained from probabilistic seismic hazard analysis using attenuation relationships for response spectrum. In this study, two UHS were developed for 10% and 2% Probability Exceedance (PE) in design time period of 50 year or correspond to return period of approximately 500 and 2,500 years, respectively. Two time histories for each hazard level were generated in this study, which represent the most likely and mean contribution magnitude-distance combinations. Finally, the time histories were applied in using 1-dimensional shear wave propagation analysis to obtain peak acceleration and amplification factor at the surface of Kuala Lumpur. The results indicate that the selection of appropriate time histories is one of the most critical in ground response analysis. The accelerations at the surface could be different up to about 35%. Keyword: synthetic time histories, uniform hazard spectra, probabilistic seismic hazard analysis 1. INTRODUCTION Acceleration time-histories are the most detailed representation of earthquake ground motion and contain a wealth of information about the nature of the ground shaking. The data are required by engineers or researchers for analyzing the performance of new or existing structures located at a specific site and the response of layered soil deposits under seismic loading. It has been known for many years that selection of time-histories appropriates for specific geological and seismological conditions play an important role for obtaining accurate results (e.g. USACE, 1999; Azlan et al, 2003). The input ground motions to such analyses are usually selected to be either representative of earthquake scenarios that control the site hazard, or consistent with predefined, "smooth" target elastic response spectra. The two methods that can be used to select earthquake acceleration time-histories at bedrock (USACE, 1999): method 1 is by utilizing existing ground motion time histories recorded near the site and method 2 is by generating artificial ground motions time histories. The advantage of procedure in method 1 is that the analysis uses natural motions that are presumably most representative of what the structure or site could experience. In this 1 Assoc. Prof. and Head of SEER 2 Ph.D Student, Faculty of Civil Engineering UTM 3 Assoc. Prof., Faculty of Civil Engineering UTM 4 Assoc. Prof., Faculty of Civil Engineering ITB