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Chapter 3 Brick Masonry & Reinforced Concrete Buildings

The extent of damage would have been drastically reduced had modern earth-
quake-resistant design procedures and construction practices been followed, e.g
the provisions of the Indian seismic codes.

The widespread damage done to infill walls requires more in-depth study. The
members, which were non-structural for gravity loads, became very effective
structurally in resisting seismic forces in the earthquake. The brittle nature of
unreinforced infills resulted in severe diagonal shear cracking and out-of-plane
instability, causing a falling hazard. The cost of repairing damages to infills can
be substantial. On the other hand, despite four decades of extensive research, a
consensus has yet to emerge on a unified approach to the design, strengthening
and ductility evaluation of infilled frames. However, there is urgent need to
develop techniques to increase the ductility of unreinforced infills which can be
used for retrofitting and strengthening already damaged walls.

In Jabalpur, the need for repair and rehabilitation is more pressing and care
should be taken that these activities are executed properly. Otherwise, the dam-
aged statistics will escalate in future earthquakes due to existing weaknesses.

REFERENCES

BIS. (1984). IS:1893-1984 Criteria for Earthquake Resistant Design of Structures
Bureau of Indian Standards, New Delhi.
BIS. (1993). IS:13920-1993 Ductile Detailing of Reinforced Concrete Structures Sub-
jected to Seismic Forces - Code of Practice Bureau of Indian Standards, New
Delhi.
BSSC. (1992a). NEHRP Handbook for the Seismic Evaluation of Existing Buildings
Building Seismic Safety Council, Washington, D.C., USA.

BSSC. (1992b). NEHRP Handbook for the Seismic Rehabilitation of Existing Buildings
Building Seismic Safety Council, Washington, D.C., USA.

Rosenblueth, E. (ed.). (1980). Design of Earthquake Resistant Structures, Pentech
Press, London, p. 215.

APPENDIX: CHANDRIKA HOMES, AMANAPURA

Several units of two storey duplex Chandrika houses in Amanapura were
severely damaged. The front masonry walls in NE-SW direction could not resist
the in-plane shear imposed by earthquake forces. These front walls were weak-
ened by openings for doors and windows and the resulting masonry piers did not
have adequate lateral strength to safely resist seismic forces. The elevation of a

Jabalpur Earthquake of May 22, 1997 65