Effective Seismic Retrofit of URM Parapets Using Mechanical Anchors as Vertical Reinforcement

The development of cost‐effective and minimally invasive retrofit strategies to address the seismic vulnerabilities of unreinforced brick masonry (URM) parapets in heritage buildings is crucial to both community resilience and preservation of cultural landmarks. This study presents an experimental program investigating the out‐of‐plane lateral response of 11 full‐scale URM parapet specimens, retrofitted using postinstalled small‐diameter mechanical anchors as vertical reinforcement. Test variables include loading protocol (i.e., cyclic vs. monotonic), anchorage configuration, anchorage embedment, and presence of strongbacks. The experimental results show that the lateral strength of the retrofitted specimens ranges from about 5 to 25 times greater than the postcracked rocking strength of the as‐built specimens. Leveraging the experimental results and the identified impact of the test variables on retrofit effectiveness, using a strength hierarchy approach, this study proposes semiempirical nominal strength equations and capacity reduction factors that can be adopted by engineers to design retrofit strategies for URM parapets using mechanical anchors. Validation using the test data shows a R 2 value of 0.75 and a failure mode prediction accuracy of 84%.