Abstract:
Unreinforced masonry is one of the most popular construction materials in
the world. It is also unfortunately, the most vulnerable against earthquakes. Damage to
unreinforced masonry buildings has caused huge number of human casualties historically
and during recent earthquakes in developing countries. Therefore, retrofitting of low
earthquake-resistant masonry structures is the key issue for earthquake disaster mitigation
in developing countries to reduce the casualties significantly. When we propose the
retrofitting in developing countries, retrofitting method should respond to the structural
demand on strength and/or deformability as well as to availability of material with low
cost including manufacturing and delivery, practicability of construction method and
durability in each region. Considering these issues of developing appropriate seismic
retrofitting techniques for masonry buildings to reduce the possible number of casualties
due to future earthquakes in developing countries, a technically feasible and economically
affordable PP-band (polypropylene bands) retrofitting technique has been developed and
many different aspects have been studied by Meguro Laboratory, Institute of Industrial
Science, The University of Tokyo. PP-band is commonly used for packing.
In order to understand the dynamic response of masonry houses with and
without PP-band mesh retrofitting, crack patterns, failure behavior, and overall
effectiveness of the retrofitting technique, shaking table tests were carried out. In this
experimental program, ¼ scale single box shape room structure with wooden roof models
were used. Addition to that, effect of surface plaster on PP-band retrofitted house model
also studied.
From the experimental results, it was found that a scaled dwelling model with
PP-band mesh retrofitting was able to withstand larger and more repeatable shaking than
that without PP band retrofitting, which all verified to reconfirm high earthquake resistant
performance. When surface finishing applied above house model, due to improve bond
connection between PP-band and brick wall, surface plaster kept well with wall.
