Seismic Performance of Masonry Walls Retrofitted for Shear Using Externally Bonded FRP

Abstract

AbstractUnreinforced masonry (URM) walls are prone to a brittle failure when subjected to out-of-plane and in-plane forces caused by seismic events. Fiber Reinforced Polymer (FRP) materials offer an economical and viable solution for the seismic retrofit of URM to increase their resistance to in-plane and out-of-plane forces. This paper presents the results of an experimental program that aimed to determine the in-plane shear performance of unreinforced concrete masonry walls strengthened with different levels of externally applied Carbon and Glass FRP composites. All the wall specimens were tested under in-plane cyclic loading with increasing intensity. The test set-up configuration consisted of double-height walls loaded at the mid-height. A total of five specimens (one control, two carbon, and two glass) were tested with increasing amounts of FRP and different layouts. The FRP was applied to one face of the walls to simulate field conditions where access to only one face of the wall is possible. The ultimate shear strength, lateral deformation, and peak load were compared for all tested walls. In most cases, failure occurred in either the masonry or the epoxy and in no case did the FRP reach its ultimate capacity. The experimental results demonstrated that a significant increase in the in-plane shear capacity of masonry can be achieved for walls retrofitted with Glass and Carbon FRP. Ultimate shear strengths of the walls were compared with those determined using the design model in ACI 440.7R for predicting the in-plane shear capacity of CMU walls. A good correlation between experimental results and theoretical predictions was observed.