UC San Diego

This study is to acquire a better understanding of the seismic performance of reinforced masonry structures at the system level, and develop reliable computational models that can predict the performance of these structures. To this end, a nonlinear finite

element modeling scheme has been developed and a two-story reinforced masonry shear wall structure was tested on a shake-table. This structure had door and window openings and wall components with low aspect ratios. A displacement-based method was used to design the two-story structure taking into account the shear-critical wall components. The structure behaved as expected under the design earthquake, but the drift levels exceeded the design limit considerably for the maximum considered earthquake. The experimental results reveal the significant contribution of the out-of-plane walls to the behavior of the structure and they have been used to validate the computational models developed in the study.

Nonlinear finite element models can be useful tools for assessing the performance of existing reinforced masonry structures, and for conducting parametric studies to evaluate different design methodologies and reinforcing details. A major challenge is to simulate the behavior of a reinforced masonry structural system with wall components that can be dominated by diagonal shear cracks or shear sliding. A general finite element modeling scheme that can predict the aforementioned failure mechanisms has been developed in this research. In this scheme, masonry is modeled with shell elements. A phenomenological law for simulating the dowel action of reinforcing bars has been proposed and implemented in a newly developed interface element that allows different mesh refinements for reinforcing bars and shell elements. An existing cohesive crack line interface model has been extended to account for the three-dimensional kinematic fields compatible with shell elements. The capability of the models to capture the response of the two-story structure has been demonstrated. Results from numerical studies have been used to validate the displacement-based design methodology and to quantify the contribution of the out-of-plane walls to the lateral load resistance of the two-story structure.