Comparison of Seismic Demand from Earthquake by Equivalent Lateral Force Procedure in Different Versions of Design Codes

Abstract

Laws or standards for analyzing and designing structure to resist the earthquake in Thailand was first mandated in 1997 (2540 B.E.) by the Ministerial Regulation No. 49 according to the Building Control Act 1979 (2522 B.E.). Since then, series of laws and standards has been followed. i.e., The Ministerial Regulation 2007 (2550 B.E.), DPT 1302-2552 2009, DPT 1301/1302-61 2018, and Ministerial Regulation 2021 (2564 B.E.), respectively. 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 Equivalent Lateral Force 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. For the Chiang Rai province case, the analysis results shows that the base shear from using the recent Ministerial Regulation 2021 (2564 B.E.) is almost double as compare to Ministerial Regulation 1997 (2540 B.E.). However, if the building is located in Bangkok, the opposite is true. The resulting base shear from ASCE7-16 is 1.20 and 1.39 times that of ASCE7-02 for Chiang Rai and Bangkok province cases, respectively. Given that the newly released codes is correct and precise, many old buildings may not be sufficiently strong and should be subject to the assessment for enhancing their resistance to possible earthquakes in the future.