Page 60 - Jabalpur_EQ

Chapter 3 Brick Masonry & Relntorced Concrete Buildings

Adjacency of Buildings
Buildings across property lines should be separated by suitable seismic gaps, oth
erwise pounding or hammering damage to structural elements at the interface is
possible. Another problem occurs when the adjacent structural units are of dif-
ferent heights. The lower building acts as a base for the upper portion of the
higher building, As a result, the lower building receives an unexpected load,
while the higher building suffers from a major vertical discontinuity at the roof
level of the lower building (BSSC 1992a).

Temple Building, Shahapur
A temple building in Shahapur suffered pounding damage due this deficiency.
As shown in Fig. 3-10, the new addition of the second floor of the meeting hall
and the extension of the slab to meet the dome of the temple created a vertical dis
continuity for the old temple structure. As a result, lateral vibrations of the dome
structure were restrained by the floor slab causing pounding damage to the tem
ple dome and floor slabs of the meeting hall.

Providing an isolation joint between the two modules of the temple building will
reduce the pounding damage, and permit both modules to move independently.
However, such deficiencies are difficult to correct satisfactorily. Increasing the
stiffness of one or both structures will reduce the seismic deformations and the
pounding damage. However, it may not be feasible solution for already stiff
buildings. In such cases, alternative load paths should be provided for vertical
load resisting elements (bearing walls and columns) which may be damaged by
the impact.

Pounding
damage to the temple
dome and floor slabs
of the meeting hall

New addition
of 2nd floor

Figure 3-10. Pounding damage
to a URM structure due to lack of
a seismic gap between its two
modules of different dynamic
properties.
Old temple & the
adjoining meeting hall

Jabalpur Earthquake of Muy 22, 1997 50