Seismic resistant retrofitting for buildings
Practical Action
Masonry confinement
The use of chicken wire mesh to confine the masonry was also suggested in the UNDP India
guideline. This would prevent large pieces of debris from falling from the wall, but would not
necessarily improve structural integrity of the building. This safety measure would simply prevent
material from falling on inhabitants.
Adobe masonry
Adobe masonry will have the same failure modes as stone or brick masonry, as mortar joints will
be fail in tension. The nature of adobe, however, means that the material will be highly variable.
Depending on the quality of the existing bricks, some of the methods outlined above may not be
fit for purpose, such as those that require an extensive number of holes to be made. Some less
intrusive methods of reinforcing adobe have been researched, as well as methods of reinforcing
historical adobe buildings.
Steel mesh reinforcement
A pilot project in Peru was implemented in 2004, retrofitting 20 houses in 6 towns based on the
research carried out by the Pontifical Catholic University of Peru (PUCP). The retrofit involved
attaching vertical strips welded steel mesh to the corners, intersections and intermediate of long
walls, with horizontal strips of mesh at the tops of walls. The mesh had typically 1mm diameter
wires with 19mm spacing. It was then covered with a cement mortar. This aimed to delay
collapse of an adobe masonry building by providing additional ductility.
An earthquake shook Peru of 7.9 Mw magnitude on 15th August 2007 just offshore near the
town of Pisco. While 80% of adobe buildings collapsed in the most affected areas, in Guadalupe,
the adobe house that had been retrofitted with steel mesh by the PUCP performed well under
this earthquake, failing only where the upgrade was not completed on part of a wall (San
Bartolome et. al., 2008). In contrast, the neighbouring buildings were seen to collapse. This
retrofit was also particularly effective because it made locals aware of the measures that could be
taken to prevent collapse in the future.
2.0 1.0 1.9
1.5 1.0 1.5
Mesh
reinforcement
1.9 1.0 2.0
Window
1.3
Adobe walls
1.0
0.9
0.45
Mesh
reinforcement
0.9
1.3
Figure 7: Illustration of wire mesh retrofit locations for a house in Guadalupe, Peru based on San Bartolome
et al. (2004).
Polypropylene mesh reinforcement
This method involves encasing unreinforced masonry in polypropylene straps (or PP-bands),
which are easy to obtain. It has had practical application in Nepal, Pakistan and Peru with
positive reception from the communities involved in the dissemination programme. A
demonstration house was constructed for locals to witness its effectiveness at withstanding
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