In-plane cyclic loading tests of concrete hollow block masonry walls retrofitted with high ductile fiber-reinforced concrete

Abstract

When subjected to horizontal loading induced by an earthquake, concrete block masonry walls generally exhibit vulnerability, particularly under high shear force. To improve the failure mode and lateral resistance of these walls, and to promote the application of concrete block units in multi-story masonry buildings, this study proposes techniques for retrofitting concrete hollow block masonry walls by installing coated high ductile fiber-reinforced concrete (HDC) layers. Six half-scale testing specimens, including three unreinforced concrete block masonry walls (URM) and three confined walls, were tested under in-plane cyclic loading to investigate their seismic performance before and after the upgrade. The test results indicate that these configurations significantly increased the lateral shear strength, stiffness, and energy dissipation capacity of the URM walls, and changed the brittle failure mode into a ductile mode. For the confined masonry walls, the lateral shear resistance and the stiffness were obviously enhanced, whereas the energy dissipation showed negligible improvement. The retrofitted walls showed higher residual strength and less damage, making them favorable for post-earthquake restoration. To estimate the ultimate shear strength of the tested specimens, relevant formulas developed in this study are presented.