Seismic Behavior of Unreinforced and Confined Brick Masonry Walls Before and After Ferrocement Overlay Retrofitting

TLDR

The study experimentally compares the in‑plane lateral load behavior of unreinforced and confined brick masonry walls before and after ferrocement overlay retrofitting. Full‑scale walls were built per common South Asian masonry practices, tested to peak resistance, retrofitted with grout and ferrocement overlay, then retested to ultimate failure, with results compared to ASCE standards for stiffness, strength, and deformation. Confined walls exhibited nearly twice the lateral load capacity of unreinforced walls, and the grout‑and‑ferrocement retrofit markedly improved the unreinforced wall’s capacity while offering only marginal gains for the confined wall, with ASCE guidelines reasonably matching the observed behavior.

Abstract

This study presents experimental results of quasi-static load test conducted on two full-scale brick masonry walls, one unreinforced and the other confined, to investigate their in-plane lateral load behavior before and after retrofitting. The walls were constructed closely following the masonry system commonly used in Pakistan and in most South Asian countries. The walls before retrofitting were tested to their peak resistance. The damaged walls were then retrofitted with grout injection followed by ferrocement overlay and retested to their ultimate failure under the identical conditions. The effectiveness of the proposed confinement and retrofitting scheme was assessed from the damage pattern, energy dissipation, and force-deformation behavior of the walls tested before and after retrofitting. The test results before retrofitting show that the capacity of confined masonry wall is almost double to that of unreinforced masonry wall. The test results after retrofitting indicate that the applied retrofitting scheme significantly enhanced the lateral load capacity of the unreinforced masonry wall, however it was marginally beneficial in the confined masonry walls. The test results are also compared with American Society of Civil Engineers (ASCE) standards in terms of stiffness, strength and acceptable deformations. It is concluded that the guidelines provide reasonable estimates of the test observations.