Seismic retrofitting of non-engineered masonry in rural Nepal

Abstract

One of the greatest causes of casualties in major earthquakes around the world is the collapse of non-engineered masonry buildings (those built without engineering input). Yet by definition non-engineered structures remain largely outside of the scope of modern engineering research, meaning that the majority of those at risk often remain so. A further barrier to realising research in this field is the significant social and economic challenge of implementation in low-income communities, where non-engineered housing is prevalent. This paper introduces a retrofitting technique aimed at preventing or prolonging the collapse of adobe (mud brick) houses under strong earthquakes. This technique uses common polypropylene packaging straps to form a mesh, which is then used to encase structural walls. The aim of this paper is to give an overview of the retrofitting technique's development and implementation.The key development stages of static, dynamic and numerical testing are presented, showing that the proposed technique effectively prevents brittle masonry collapse and the loss of debris. An implementation project is then discussed, involving a training programme for rural masons in Nepal, a public shake-table demonstration and the retrofit of a real house. The implementation project proved effective at reaching rural communities but highlighted that government subsidies are required to incentivise the safeguarding of homes among low-income communities.

Award-winning papers in 2012

“…The Frederick Palmer Prize, awarded for the best paper on structures or buildings, was awarded to Macabuag et al (2012).…”

Built Environment Infrastructure Design: Some Lessons from the Past

“…One such method consists of wrapping adobe buildings with strips of tree bark that are subsequently encapsulated in a mud bonding "mortar" to encourage composite behavior between the bark and the adobe substrate [4]. A modern version of this, making use of stronger, more reliable materials such as steel wire mesh or polypropylene mesh, has been used in Peru [5] and Nepal [6], respectively. Another form of rehabilitation used in Iran consists of the use of adobe bricks laid in a "herring-bone" pattern to fill in the extensively damaged parts of walls.…”

Effect of Roof and Diaphragm Connectivity on Dynamic Behaviour of the PP-band Retrofitted Adobe Masonry Structures

“…PP meshing uses common PP packaging straps (PP bands) to form a mesh, which is then used to encase masonry walls by fixing to both faces of walls. The mesh prevents the separation of structural elements and the escape of debris, maintaining sufficient structural integrity to prevent collapse [2]. Past studies show that PP-band retrofitting improves the integrity of structural components and prevent the collapse of masonry structures during an earthquake [3][4][5][6][7].…”