A Nonlinear Numerical Model and its Utilization in Simulating the In-Plane Behaviour of Multi-Story R/C frames with Masonry Infills

This paper presents first a valid, fully non-linear 2-D numerical model that can capture realistically the in-plane hysteretic behaviour of reinforced concrete (R/C) frames with masonry infills when they are subjected to combined vertical and cyclic horizontal loads in order to predict their post-elastic earthquake bahaviour. The effectiveness of this simulation was validated by comparing the numerically predicted behaviour with results from a series of pseudo-dynamic tests whereby a number of 1:3 scale, one-bay, one-story R/C frame specimens, including relatively weak masonry infills, were subjected to combined vertical and cyclic horizontal seismic-type loads. The role of the interface between the masonry infills and the surrounding concrete frame was also included in this simulation. Next, this paper deals with the applicability of this successful non-linear masonry-infill concrete-frame numerical simulation to predict realistically the seismic behaviour of prototype multi-story R/C frame structural formations with masonry infills. The major obstacle here is the computational time and memory requirements needed for the completion of such a numerical analysis including all the nonlinear mechanisms which were employed in the preceding simulation of the single-story one-bay R/C frame with masonry infills. In order to overcome this obstacle, use was made of an equivalent post-elastic “pushover” type of analysis that draws information on the stiffness and strength variation from one-bay, one-story R/C masonry infilled unit frames that compose a given multistory structural formation. In doing so, the fully non-linear numerical simulation of the single-story units that compose this structural formation, presented in the first part, is utilized.