The strength of masonry in out-of-plane horizontal flexure, with stresses parallel to the bed joints, is an important parameter in the design of walls for lateral loading. Stress distributions in this type of behaviour are complex and little understood, leading to simplified assumptions or empirical relationships in design codes. The paper summarizes experimental and analytical work on horizontal flexure for clay brick masonry.

Experimental results for a large number beams are presented and empirical relationships defined. A detailed description of the load-deflection behaviour of a masonry beam and the development of cracks prior to failure is given. Simplified moment analysis is used to generate an approximate understanding of behaviour. A detailed analysis of curvatures in bricks an mortar joints is then used to estimate flexural stiffness which is compared with test results. The effect on flexural properties of unfilled perpend joints is also discussed. The results provide a better understanding of flexural behaviour in masonry and can be used to formulate more rational design rules.