Seismic Vulnerability Assessment of Non-Engineered Masonry Buildings in Malawi

Abstract

Malawi is located within the southern branch of the active East African Rift System, where earthquakes of Mw 7.0 (or greater) can occur along major faults. In Malawi, the majority of dwellings in both formal and informal settlements are non-engineered unreinforced masonry constructions, built by local artisans with little input from engineers. These constructions are highly vulnerable to seismic events due to poor materials and lack of construction detailing. This study develops analytical vulnerability functions that enable the assessment of seismic capacity of typical buildings in Malawi. Since the seismic vulnerability greatly depends on building characteristics, geometrical and structural data are collected by conducting semirapid surveys of 300 houses located in urban and rural areas of Central and Southern regions of Malawi. Mechanical properties of the local materials are also obtained from an experimental campaign. In this work, a mechanical method FaMIVE (Failure Mechanism Identification and Vulnerability Evaluation) is adopted and the effects of both in-plane and out-ofplane behaviour of the masonry structures are taken into consideration to derive capacity curves for seismic vulnerability assessment. Special attention is given to 1) the Malawian building typologies as described in the Word Housing Encyclopedia and 2) failure mode classes for the Malawian constructions as calculated by FaMIVE. Hence, the derived vulnerability functions can serve as a benchmark for typical buildings in Malawi. The results and conclusions are also relevant for other East African countries, where similar construction techniques are adopted.