Modification of Chinese-code formula for equivalent lateral force method

The equivalent lateral force method is one of the commonly used methods for the seismic design of building structures. The assumptions included an equivalent coefficient of 0.85 when determining the equivalent total weight of the structure, and the horizontal seismic action distributed as an inverted triangle pattern is used in the existing formula in relevant Chinese codes. And the two assumptions make a big difference between the calculation results of the equivalent lateral force method and the mode-superposition response spectrum method in Chinese code. The dynamic structural parameters of the designed six reinforced concrete frame structures and the calculated case structure, which were designed according to Chinese codes, are extracted in this paper. The six structures are analyzed using the mode-superposition response spectrum method and the equivalent lateral force method in Chinese code, respectively. The comparative analysis results show that shear forces at the bottom of structures calculated by the equivalent lateral force method in Chinese code is smaller, but the horizontal displacement of each storey of the structure is larger. Aiming at the shortcomings of the equivalent lateral force method in Chinese codes, combining with the calculation results of the mode-superposition response spectrum method, a modified calculation formula of the equivalent lateral force method is proposed. The calculation results of the modified equivalent lateral force method established in this paper are superior to the calculation results of the equivalent lateral force method in Chinese codes through examples verifications.