A simplified approach to simulate in-plane lateral response of reinforced concrete frames with masonry infills

Abstract

For seismic design or performance assessment, reinforced concrete (RC) frame buildings with masonry infills are often modeled using strut-cum-masonry constitutive models. A number of models have been considered in the past to simulate in-plane lateral response of infilled RC frames. However, these models lead to substantially different simulation results. Further, guidance on selecting a model is limited, and at times divergent. In the present study, a simplistic framework was considered to quantify the lateral response. In a stage-wise manner, eight previously proposed masonry constitutive models and their variants were used in combination with a three-strut model to simulate the lateral response of 106 one-bay-one-story infilled RC frame specimens. The process helped identify functional forms for the parameters of a new masonry constitutive model. Strength parameters defined in terms of the product of masonry prism strength and cross-sectional area of struts, and stiffness parameters defined in terms of the masonry elastic modulus and cross-sectional area of struts divided by masonry diagonal length led to optimal coefficients of variation for the calculated response parameters for infilled RC frames. Multipliers were established for ranges of masonry prism strength so that simulated response was similar to experimental observation on an average. Simulation results were not significantly correlated with relevant strength parameters of the RC frame, relative stiffness parameter, and observed failure modes. The proposed model can be used in combination with one or two struts. However, single-strut model should be avoided if capturing shear failure in frame members is important.