RESPONSE OF CONCRETE BLOCK MASONRY WALLS SUBJECTED TO IN-PLANE SHEAR AND FLEXURAL LOADS

This paper presents the results of a study onthe in-plane seismic performance of full-scale unreinforced concrete block masonry (URCBM) walls, commonly constructed in Iran, using numerical simulation. Considering limited studies in this field, an experimental research with the objective of investigating the behaviour of these walls under in-plane lateral loading, is first performed on small-scale masonry wall. The numerical modeling based on micro-modeling, is then developed and calibrated to present similar inelastic load-displacement response and failure mode to those of the tested specimens. After verifying the numerical model, a parametrical study is performed on 3D,full-scale dimensions URCBM wallshaving different aspect (height/length) ratios of 0.5, 0.75, 1, 1.5 and 2, and also with two different boundary conditions; cantilever (flexural behaviour) and fixed (purely shear behaviour). The nonlinear static (pushover) analyses results show that the walls boundary conditions have a profound effect on the lateral behaviour and mode of failure of masonry walls. The failure mechanism of fixed ends walls is predominantly shear, whereas, failure in cantilever walls is generally due to rocking.Also, the lateral capacity of walls decreases with increase of aspect ratio.