In plane lateral strength of reinforced masonry walls

In the design of reinforced masonry (r.m.) structures in seismic zones, the lateral strength of structural walls is usually evaluated by means of code formulae or analytical expressions derived from experimental results. However, recent studies have indicated that current empirical formulations can reasonably predict the lateral strength of r.m. walls that fail in a flexural mode, while reliability for shear strength is rather limited. In this paper, a simple and rational analytical model for the prediction of the shear strength of r.m. wall panels is developed. The model is based on the Modified Compression Field Theory and offers the advantage that an explicit consideration of equilibrium and compatibility is given. Moreover, empirical assumptions are restricted to the level of constitutive laws of the materials. The reliability of the model is verified by comparing the calculated capacity strength to the measured strength for about 50 wall specimens reported in literature. These comparisons indicate that the proposed model is capable of predicting the correct failure mode and of calculating the lateral strength of wall panels with sufficient accuracy. For practical design purposes, a series of interaction diagrams are also reported, which allow an easy evaluation of the capacity strength of r.m. wall panels for various combinations of the main design parameters.