Efficiency assessment of ground motion intensity measures in the estimation of dynamic response of reinforced concrete moment frames

Abstract

Selection of appropriate accelerograms for nonlinear dynamic analysis is one of the most important challenges due to their significant influence on the interpretation of analysis results. A rational method for initial refinement of ground motion records with a minimum computational cost is application of refining process based on an optimum intensity measure (IM) which is able to predict the structural responses in a reliable manner. In this research, a list of intensity measures is considered to determine most effective ones from the point of view of effective relation with the dynamic response of the structure. Selected models in this paper includes four two-dimensional (2D) reinforced concrete (RC) structures of 2, 4, 8, 12 and 20 story with special moment-resisting frame (SMRF) system, which are modeled nonlinearly. Collapse capacity of the structures was obtained using the intensity measure spectral acceleration at the first-mode period of structure Sa(T1) and the Incremental Dynamic Analysis (IDA) under the influence of 40 ground motion records selected from the refined data set to observe the gradual behavior of the structure from the linear stage to collapse. Finally, by establishing a statistical relationship between the dynamic response parameters and 27 intensity measures with the use of Pearson correlation index, the most effective intensity measure that All have an integral form and independent from the period of structure, for each of the selected structures was introduced. By examining the results, it can be said that for the 4 story low-rise structure, the Response Spectrum [Housner] intensity measure and for the 8 and 12 story mid-rise structures, the Housner intensity measure and finally, for the 20 story high-rise structure, the Displacement Response Spectrum intensity measure has the highest correlation among the intensity measures studied.

Keywords

• reinforced concrete moment frames
• intensity measure
• incremental dynamic analysis
• collapse capacity
• efficiency