Seismic damage and retrofitting identification in unreinforced masonry Churches and bell towers by the september 19, 2017 (Mw = 7.1) Puebla-Morelos earthquake

Abstract

Unreinforced masonry is one of the main construction materials used in the edification of most historical buildings around the world. This is due to its availability in nature, low-cost benefits and durability. Churches and bell towers were built to mainly withstand vertical loading induced by self-weight, disregarding the lateral performance mainly by the limitations of masonry. These massive structures present poor seismic performance due to the low tensile strength of masonry, lack of structural integrity, elevated seismic forces and heterogeneity. The last plays an important role in the in-plane and out-of-plane behavior/failure by anisotropy. This paper is aimed at presenting post-earthquake investigations in damaged Churches and bell towers by the September 19, 2017 (Mw = 7.1) Puebla-Morelos Earthquake which damaged thousands of historical buildings. These buildings presented partial and total collapses in façades, domes, vaults, arches and bell towers. The structural vulnerability, combination of materials, large openings and reduced vertical loading at top parts of belfries induced a rapid propagation of heavy damage which ended in brittle collapses. The widespread damage was induced by the missing compatibility of deformations and integrity among structural elements/materials and previous damages. These post-earthquake observations are aimed at identifying the behavior/failure of these buildings to propose practical intervention measures. The most suitable retrofitting materials/strategies were identified as practical applications for walls, bell towers, domes, vaulted covers and timber roofs/slabs to increase the displacement/strength capability by inducing more ductile failure with increased EQ energy dissipation through the enhanced hysteretic behavior.