A framework for evaluating the risk of the out-of-plane mechanism of masonry façades subjected to earthquake excitations is presented. The effect of seismic events on masonry façades is investigated and results are presented in terms of fragility curves and seismic risk for several masonry supporting restrictions. The restrictions considered are (1) masonry façade unrestricted to rock on a firm base, (2) masonry façade restricted to rock in one direction, and (3) restrained rocking masonry façade in one-sided motion. Because the available empirical information is insufficient to obtain fragility functions for masonry façades, the study is based on numerical analysis and recent studies on seismic risk. The conceptual framework is illustrated with information from masonry façades characteristic of Mexican religious structures and within the seismic hazard areas of Mexico. Since the frequency characteristics of ground motions strongly depend on the distance from the epicenter to the site, which is of cardinal importance to the vulnerability of these structures, the impact of this distance for hard-soil sites is thoroughly investigated. The probability of failure for the three types of masonry façades was calculated. It was found that the probability of failure decreases with an increased width-to-height relation; conversely, the probability of failure (reported in terms of the reliability index) increases with increased block size dimensions. Results in this study show that restraining conditions of the façades inconsequentially affect the probability of failure. Although the reliability of freestanding masonry façades are marginally greater, this finding holds true regardless of whether or not one considers far-field ground motions. The results in this study can be useful for evaluation and reinforcement tasks of masonry façades located in areas of high seismic hazard.

提出了评估地震激励下砌体立面面外机理风险的框架。研究了地震事件对砌体立面的影响，并以易碎曲线和几种砌体支撑限制的地震风险来表示结果。所考虑的限制是：（1）砌体立面不受限制地在坚硬的基础上晃动；（2）砌体立面受限制在一个方向上的岩石；（3）限制砌体立面以单向运动的形式。由于可用的经验信息不足以获取砌体立面的脆性函数，因此该研究基于数值分析和有关地震风险的最新研究。墨西哥宗教建筑的砌体立面信息以及墨西哥地震危险区域内的信息说明了概念框架。由于地面运动的频率特性在很大程度上取决于从震中到站点的距离，这对这些结构的脆弱性至关重要，因此，应彻底研究该距离对坚硬站点的影响。计算了三种类型的砌体立面的破坏概率。结果发现，随着宽度与高度关系的增加，失效的可能性降低。相反，失败的可能性（以可靠性指标报告）随着块大小的增加而增加。这项研究的结果表明，立面的约束条件对破坏的可能性没有影响。尽管独立式砌体立面的可靠性稍高，但无论是否考虑远场地震动，这一发现都是正确的。本研究的结果可用于评估和加固高地震危险区域的砌体立面的任务。