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.

由于建筑寿命长、设计方法不当、材料性能脆、施工工艺差等原因，现有砌体结构大多在地震时表现不佳。现有砌体建筑的改造广泛采用外加钢网砂浆层的改造方法。合理有效地评价外加钢丝网砂浆层加固砌体墙体的抗震性能是砌体结构研究领域的一个难点课题。基于有限离散元组合方法，建立了四种不同砌体砂浆强度的外砂浆层改造砖墙的数值模型。详细讨论了砂浆的剪切强度以及改造砂浆层与砖块之间的接触情况。通过对数值模型施加低周往复荷载，得到了改造砖墙的破坏模式和荷载-位移曲线，通过比较破坏模式、极限承载力、变形能力等方面进行了测试。本研究为改进砌体结构抗震加固设计方法提供依据，有助于更好地评估砌体结构改造后的抗震性能。变形能力等方面进行了测试。本研究为改进砌体结构抗震加固设计方法提供依据，有助于更好地评估砌体结构改造后的抗震性能。变形能力等方面进行了测试。本研究为改进砌体结构抗震加固设计方法提供依据，有助于更好地评估砌体结构改造后的抗震性能。