How to make Stone Masonry Buildings Earthquake Resistant?
Earthquake Tip 16
Learning
Earthquake Design
and
Construction
Behaviour during Past India Earthquakes
Stone has been used in building construction in
India since ancient times since it is durable and locally
available. There are huge numbers of stone buildings
in the country, ranging from rural houses to royal
palaces and temples. In a typical rural stone house,
there are thick stone masonry walls (thickness ranges
from 600 to 1200 mm) built using rounded stones from
riverbeds bound with mud mortar. These walls are
constructed with stones placed in a random manner,
and hence do not have the usual layers (or courses)
seen in brick walls. These uncoursed walls have two
exterior vertical layers (called wythes) of large stones,
filled in between with loose stone rubble and mud
mortar. A typical uncoursed random
(UCR) stone
masonry wall is illustrated in Figure 1. In many cases,
these walls support heavy roofs (for example, timber
roof with thick mud overlay).
Laypersons may consider such stone masonry
buildings robust due to the large wall thickness and
robust appearance of stone construction. But, these
buildings are one of the most deficient building
systems from earthquake-resistance point of view. The
main deficiencies include excessive wall thickness,
absence of any connection between the two wythes of
the wall, and use of round stones (instead of shaped
ones). Such dwellings have shown very poor
performance during past earthquakes in India and
other countries (e.g., Greece, Iran, Turkey, former
Yugoslavia).
In
the 1993 Killari
(Maharashtra)
earthquake alone, over 8,000 people died, most of
them buried under the rubble of traditional stone
masonry dwellings. Likewise, a majority of the over
13,800 deaths during 2001 Bhuj (Gujarat) earthquake is
attributed to the collapse of this type of construction.
The main patterns of earthquake damage include:
(a)