Seismic optimization design of reinforced concrete frames: uniform displacement criterion

In the seismic design specification of each country, the displacement of reinforced concrete frames is a significant parameter for evaluating structural safety. For structures designed according to traditional methods, the maximum story drift ratios of some stories are obviously larger than those of other stories, which threatens structural safety. This paper proposes a uniform displacement optimization method for reinforced concrete frames to address the weak story issue. This method can be implemented through the automatic operation of MATLAB and OpenSEES. It is presented based on four reinforced concrete frames with different heights. The design formulas of optimal component reinforcement ratios were obtained by fitting the design results. The universality of the design formulas was verified through nonlinear time history analysis, incremental dynamic analysis, and seismic fragility analysis. The results indicate that the story drift ratio distributions were closely related to the reinforcement ratios of components. The story drift ratio distributions of reinforced concrete frames subjected to various earthquake records were similar. The design formulas can therefore make story drift ratio distributions more uniform when structures are subjected to earthquake records with different intensities.