Seismic Performance Assessment of Low-Rise Unreinforced and Confined Brick Masonry School Buildings Using the Applied Element Method

Abstract

Masonry buildings are generally vulnerable to seismic action, as evidenced extensively in past earthquakes. In order to improve their seismic performance, several modifications have been introduced, such as reinforcing or confining the masonry. This paper presents a seismic analysis and fragility assessment procedure for non-engineered masonry building typologies, employing the applied element method (AEM). Compared to buildings with stiff diaphragms, the conventional pushover-based procedure is challenging for the seismic assessment of masonry buildings with flexible diaphragms, due to the lack of a global box-like behaviour. This study first presents a novel and validated method for nonlinear pushover analysis, independent of the type of diaphragm action on the building, by applying incremental ground acceleration and by considering suitable engineering demand parameters for the assessment of lateral capacity. Based on the failure mechanisms, a seismic performance assessment and fragility evaluation approach is then proposed, for reliable accounting of both the in-plane and out-of-plane failure modes. Finally, the proposed methodology is applied to a number of unreinforced and confined masonry school buildings with different seismic detailing levels, as often found in the Himalayan belt and beyond.

Keywords

• unreinforced masonry
• confined masonry
• non-engineered construction
• school buildings
• box-like behaviour
• flexible diaphragms