Cyclic Analyses of Reinforced Concrete Masonry Panels Using a Force-Based Frame Element

This paper presents the calibration of a frame element that can be used to model the flexural as well as the shear behavior of reinforced masonry panels subjected to monotonic and cyclic loads. The element can be used in the equivalent frame method to analyze masonry wall systems, and is based on a force-based Timoshenko beam element formulation that combines a fiber-section model with a phenomenological nonlinear shear law. The element was originally applied to the analysis of reinforced concrete frames, and has been recently extended to unreinforced masonry structures. Well-established constitutive laws are used for masonry and steel reinforcement. The constitutive law for shear requires special attention in order to correctly predict the shear force-deformation response of masonry walls, accounting for the presence of shear reinforcement. A procedure to calibrate the parameters of the shear law is presented. The effectiveness, accuracy, and simplicity of the force-based Timoshenko frame element and the calibration method are validated by results of experimental tests. Even though the element is general and can model any reinforced masonry panel, the applications of this paper focus on panels made of hollow concrete blocks.