Estimating transverse strength of masonry infills

A simple calculation method is given for estimating out-of-plane strength of unreinforced masonry infill panels. Development of the method is reviewed starting with a description of a series of large-scale experiments, a brief presentation of sample test results and formulation of an analytical model. A series of eight masonry infill panels were made of either concrete or clay masonry units. Test panels were first subjected to in-plane horizontal forces to crack them, and then loaded with transverse pressures. The purpose of the research was to investigate how transverse strength is reduced when a panel is cracked with in-plane shears. Test results showed a substantial out-of-plane strength even for cracked panels because of arching effects. Axial thrusts developed in a panel were reacted against the surrounding reinforced concrete frame. An analytical model for arching behavior in plates was developed based on these observations. The model then served as the foundation for an evaluation Procedure that is highlighted with this paper. The paper emphasizes how the suggested evaluation procedure was developed and verified. An illustrative example on its use is provided.