This report documents one experimental investigation which is part of an overall program of research on the properties of concrete masonry. The primary objective of this testing was to evaluate the effect of the quantity and the distribution of horizontal reinforcement on masonry walls under cyclic in-plane loading which fail by a shear mode (primarily diagonal cracking). The ten wall specimens in the current investigation were subjected to an average of over forty loading cycles. Nine to eighteen of these cycles were applied before yield and loss of load capacity. The walls were subjected to cycles of increasing displacements separated by “degradation cycles.”
All ten walls were seven courses high (56 inches or 1.42 m) and three blocks wide (48 inches or 1.22 m) and made from similar concrete block and mortar. The concrete blocks used were hollow block having a unit compressive strength of 1900 psi (13.1 MPa) based on the gross area. The mortar was proportioned as type S. Reinforcement was provided by two types of steel. Rebar steel was placed in grouted bond beams. As an investigation of an alternative method, 9-gage ladder type reinforcement was placed in the bed joint of some walls. Axial load was 39.3 kips (174.9 kN), resulting in a uniformly distributed pressure on the net cross section of 200 psi (1.38 MPa).