Numerical simulation on the seismic performance of retrofitted masonry walls based on the combined finite-discrete element method

Due to the long construction life, improper design methods, brittle material properties and poor construction techniques, most existing masonry structures do not perform well during earthquakes. The retrofitting method using an external steel-meshed mortar layer is widely used to retrofit existing masonry buildings. Assessing the seismic performance of masonry walls reinforced by an external steel-meshed mortar layer reasonably and effectively is a difficult subject in the research field of masonry structures. Based on the combined finite-discrete elements method, the numerical models of retrofitted brick walls with four different masonry mortar strengths by an external mortar layer are established. The shear strength of mortar and the contact between the retrofitted mortar layer and the brick blocks are discussed in detail. The failure patterns and load-displacement curves of the retrofitted brick walls were obtained by applying low cycle reciprocating loads to the numerical model, and the bearing capacity and the failure mechanism of the retrofitted walls were obtained by comparing the failure patterns, ultimate bearing capacity, deformability and other aspects with the tests. This study provides a basis for improving the seismic strengthening design method of masonry structures and helps to better assess the seismic performance of masonry structures after retrofitting.