Comparison of Seismic Demand from Earthquake by Response Spectrum Analysis Procedure in Different Versions of Design Codes

Abstract

Details for analyzing and designing of structures for resisting earthquake in Thailand by dynamic approach was first published in 2009 (2552 B.E.) by the Department of Public Works and Town & Country Planning in DPT1302-52. The most recent version the Ministerial Regulation 2021 (2564 B.E.) which adopted the DPT1301/1302-61. Abroad, UBC1985, ASCE7-02, ASCE7-05, ASCE7-10, ASCE7-16, and recently ASCE7-22 have been released. This paper reports the comparison study of resulting seismic demands by using the Response Spectrum Analysis procedure specified in different versions of design codes. A case study of a 14.4 x 28.8 m x 5 floors building with special reinforced concrete moment resisting frame is used for the analysis. It is assumed that the building is located in Chiang Rai province and Bangkok. The results shows that DPT1301/1302-61 or the Ministerial Regulation 2021 gave 3.22 and 3.95 times higher base shear than DPT1302-52 for designing the vertical structural member of building in Chiang Rai and Bangkok provinces, respectively. Meanwhile, the ASCE7-16 gave 1.43 and 1.48 times higher base shear than ASCE7-02 for Chiang Rai and Bangkok province cases, respectively. For all cases, the story drifts are still within the allowable limit and the buildings are stable against the overturning moments. The significant increase of the base shear by using DPT1301/1302-61 indicates that the columns and walls may need to be re-designed or retrofit in order to increase the shear capacity. This implies changing the size or amount of reinforcement of the structural members.