No abstract

Malawi is an earthquake-prone country that lies within the East African Rift. A large proportion of its population lives in non-engineered single-storey constructions made of clay bricks and low-strength mortar. Walls are typically single-skin and often lack adequate wall-to-wall connections, leaving them vulnerable to seismic actions. This work reports a comprehensive study on the seismic fragility of unreinforced masonry buildings of the Malawi housing stock. The probability of exceeding different levels of in-plane/out-of-plane damage is estimated by considering the aleatory and epistemic uncertainties of the problem. Inter-building and intra-building variability are accounted for by adopting material test results and building survey data collected in Malawi. The inplane capacity of building walls is calculated through a finite element model that considers the orthotropic properties of masonry. The out-of-plane capacity is computed using an analytical solution, developed for walls in one way bending. In addition, record-to-record variability is considered. The new country-specific fragility models result more conservative that global estimates, which reflects the high vulnerability of Malawian masonry buildings. These fragilities can be integrated into catastrophe modelling platforms for earthquake risk assessment in Malawi and in the wider East African region.

In this article, a bi-directional flax fiber fabric with room temperature curable epoxy was used to confine concrete cylinders. The compression performances of the confined cylinders were tested on the compressive behaviors. For comparison, unidirectional basalt fiber fabric reinforced polymer (BFRP) confined cylinders were also tested. Compared to the BFRP wet layups, the flax fiber reinforced polymer (FFRP) composite exhibits nonlinear in tension, and relatively lower tensile strength and modulus, but higher elongation. FFRP in weft direction exhibits higher strength and modulus but lower elongation than that that in warp direction. The compressive test results of confined concrete cylinders indicate that FFRPs improved the ultimate strain and stress of the confined cylinders, remarkably. The coefficients of confinement of FFRP on the ultimate compression stress are slightly higher than that of BFRP. The confined cylinders with FFRP showed much higher ultimate axial strain than those with BFRP.

This study presents a building classification scheme for residential houses in Malawi by focusing upon informal construction, which accounts for more than 90% of housing in the country with the highest urbanisation rate in the world. The proposed classification is compatible with the Prompt Assessment of Global Earthquakes for Response (PAGER) method and can be used for seismic vulnerability assessments of building stock in Malawi. To obtain realistic proportions of the building classes that are prevalent in Malawi, a building survey was conducted in Central and Southern Malawi between 10th and 20th July 2017. The results from the survey are used to modify the PAGER-based proportions of main housing typologies by reflecting actual housing construction in the surveyed areas. The results clearly highlight the importance of using realistic building stock data for seismic risk assessment in Malawi; relying on global building stock information can result in significant bias of earthquake impact assessment.