Non-linear Static Analysis of Masonry Structures by means of Equivalent Frames Simplified Approach

Non-linear static analyses are the most effective way to predict force-displacement curves of masonry structures, due to the complex non linear behaviour of masonry panels which makes inadequate any kind of linear static analyses. Nevertheless, the choice of the appropriate model to use is a matter of paramount importance, as many aspects must be taken into account in order to reach a good approximation of the structural response. Many structural models aimed at predicting masonry buildings response have been proposed in recent years; these models often try to achieve a balance between the complexity of the model itself and the accuracy of obtained results. Within this framework, the equivalent frame approach has been frequently adopted in order to simulate the response of masonry building. This paper deals with the elaboration of the software FREMA (FRame Equivalent Masonry Analysis) aimed at predicting the force-displacement curve of masonry walls subject to in-plane forces. A procedure for the non-linear static analysis under displacement control has been developed; geometrical and mechanical non-linearity have been taken into account. The computer program herein developed has been validated by means of a comparison with experimental and numerical data available in literature. A further comparison between the proposed model and accurate models (FEM models) available in literature has been developed, in order to investigate the accuracy of the model and to underline the main approximations introduced by the simplified approach.