Different FEM models of reinforced concrete frames stiffened by infill masonry for lateral loads

Abstract

The aim of the paper is to introduce how to model more accurate masonry infilled reinforced concrete frames with commercially available FEM software. We developed some numerical models. One question is how to model the infill masonry for monotonic increasing lateral load? Three different numerical models were investigated. The simplest model is the equivalent diagonal strut model, where the masonry wall is replaced by a compressed diagonal strut. The next model is the orthotropic surface model, where the masonry wall is taken into account as a membrane or shell surface. Between the RC frame and the boundary of the surface are modelled with special spring and contact elements. The last model is called ``suggested sophisticated model´´, where the bricks and the mortar layers are separately modelled. The brick is taken into consideration as an orthotropic membrane element, while the mortar layers are substituted with short perpendicular and diagonal equivalent compressed struts. In case of all models small displ acements are assumed. We give the necessary data to the material properties in accordance with Eurocode 6. In this paper ``only´´ one numerical example is presented to demonstrate the operability of the different models. In the next step the practical usability and the verification with experiment results of the different models will be presented in another article.