Comparison of Experimental and Analytical Results on Masonry Infilled RC Frames for Cyclic Lateral Load

Abstract

The aim of the paper is to give a suggestion to the structural engineers to model masonry  infilled reinforced concrete frames. We made several experiments, and developed some  numerical models. Our previous papers [12–15] we showed three different FEM numerical models (equivalent diagonal strut model, orthotropic surface model and "suggested sophisticated model"), and we made a comparison study between the numerical results and the experimental tests in case of monotonic increasing lateral loads. The experiments were continued with cyclic lateral loads. Using the earlier proposed bi-linear σ - ε curve of the masonry infill and the dierent Young’s moduli to model unloading, which are based on EC6, shows good correlation with the test results, but unfortunately these are not enough precise to calculate the size of the areas under the load-displacement curves, so we obtained wrong  damage parameters. We suggest a new trilinear σ - ε curve. Using this proposed trilinear σ - ε curve of the masonry infill, which is based on EC6, using the "Suggested sophisticated model" with the equivalent struts of the mortar layer shows good correlation with the  experimental test results. Both of the calculated dissipated energies can be calculated in good approximation also before and after the yield point of the infill masonry, thus are already  usable to calculate the damage parameter D, which were determined by energy concept. With the help of the damage parameter D, a comprehensive damage-equivalent curve f (D) is  suggested to calculate the cyclic degradation of the two-storey, one-bay, masonry infilled RC frames.