Finite-element modeling of nonlinear behavior of masonry-infilled RC frames

The evaluation of the seismic performance of masonry-infilled reinforced concrete (RC) frames has been a major challenge for structural engineers. This paper addresses pertinent issues on the development and calibration of nonlinear finite-element models for assessing the seismic performance of these structures. The modeling scheme considered here combines the smeared and discrete crack approaches to capture the different failure modes of infilled frames, including the mixed-mode fracture of mortar joints and the shear failure of RC members. A systematic approach is presented here to calibrate the material parameters, and the accuracy of the nonlinear finite-element models has been evaluated with experimental data. The comparison of the numerical and experimental results indicates that the models can successfully capture the highly nonlinear behavior of the physical specimens and accurately predict their strength and failure mechanisms. The validated models have been used to assess the sensitivity of the numerical results to the modeling parameters and to identify the critical material parameters through a parametric study.