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Chapter 3 Brick MaSOnry

& Reinforced

Concrete

Buildings

Un-Reinforced Masonry (URM) constructions are extremely vulnerable to earth-
quake forces and it has been demonstrated again during the Jabalpur earthquake.
A large number of conventional URM structures suffered extensive damage near
the epicentral regiorn. The popular mixed construction (i.e., RC slabs and/or
frames in one direction with load bearing brick walls) had limited success for
buildings taller than two storeys. The reinforced concrete (RC) frame buildings
exhibited superior performance in comparison with URM structures. However,
the brick infills which were used as curtain walls or load bearing walls experi-
enced severe cracking and dislodged bricks posed a serious falling hazard.

This chapter first describes the general damage pattern of URM and RC buildings
which is followed by case studies that show typical or noteworthy performance
or damage to such structures. A brief account of various seismic deficiencies
pesent in these structures is also provided along with a list of suggestions for
remedial works. This chapter also discusses the performance of masonry infills in
the weak RC frames

DAMAGE PATTERN

The structural damage was contained within a limited area of about 15 km
around the epicenter. However, the intensity distribution was rather patchy, as
discussed in Chapter 1. The earthquake's shallow depth and high accelerations
resulted in an abnormally large percentage of the building damaged beyond
repair. The maximum MM intensity of VIlI was observed near the epicenter in
Ordnance Factory, Khamaria (OFK); Ranjhi and Ghana area in the north; and in
Koshamghat in the south. Inside the OFK campus, about 6 km from the epicenter,
most of 3 474 residential buildings suffered from Type 3 to Type 4 damage, and
about 10% of these were in hazardous condition and needed to be demolished.

Jabalpur Earthquake of May 22. 1997 41