Seismic Assessment of Unreinforced Concrete Block Masonry Buildings Before and After Retrofitting: A Case Study

Abstract

Abstract: This article presents the results of a case study on the performance of unreinforced concrete block masonry building system. The configuration and materials used for the single-story building are typical of those found in the northern areas of 2005 Kashmir earthquake. The retrofitting of the building was done using Ferro-cement overlay and cement based grout injection. Combined shear and flexure failure was observed during the test before retrofitting. The lateral load capacity of the retrofitted building was significantly improved and the damage mechanism was transformed from mixed compression-flexureshear to a more stable flexural rocking mode. Damage patterns and deformation behavior of the retrofitted structure are compared to the intact structure to quantify the benefits of retrofitting scheme, which is proposed as an efficient approach for the rehabilitation of the existing buildings. Study data were analyzed and presented in the form of force-deformation loops and envelope curves. Based on the measured data, different performance levels before and after retrofitting of the structure have been established. The results from this study are expected to guide future efforts on development of design recommendations and vulnerability assessment of buildings. Keywords: Earthquake; Unreinforced Concrete Block Masonry; Retrofitting; Quasi Static Test; Ferro-Cement Overlay; Rehabilitation; Vulnerability assessment;