Out-of plane strengthening of unreinforced masonry walls using near surface mounted fibre reinforced polymer strips

Abstract

The development of cost effective minimally-invasive seismic retrofit techniques is required for clay brick unreinforced masonry (URM) buildings because of their recognised poor seismic performance. A laboratory-based experimental study with well defined but artificial boundary conditions, which utilises constituent construction materials that replicate the material properties of masonry found in historic URM buildings, is currently addressing this need. The purpose of this study is to investigate the performance of near-surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips as a seismic retrofit solution for out-of-plane lateral loading of the walls in URM buildings. In addition, five retrofitted URM walls located in four different buildings were tested in-situ by applying out of plane loading, to complement the laboratory-based study. Testing confirmed that the NSM CFRP retrofit technique is an excellent minimally-invasive and cost effective option for seismic strengthening of URM buildings. Provisional details of the design methodology for the NSM CFRP retrofit technique, and laboratory and in-situ test results are reported. Two recent projects that implemented the NSM CFRP technique are also briefly presented.