Page 53 - Jabalpur_EQ

Chapter 3 Brick Masonry & Reintorced Concrate Bulldings

and structural deficiencies observed in the Jabalpur earthquake is sum: arized in
the following sections. It should be noted that often a combination of several defi-
ciencies acting together led to failures.

Plan Irregularities

New Hostel, Agriculture University
Common plan irregularity originates from the single odd shape or when various
modules cf a building offset each other. Buildings withL-, T-, X-, U-, H-, and E-
shaped plans suffer more damage than buildings with rectangular foot prints. In
such shapes, the lack of continuity exists at the re-entrant corners. As a result,
large tensile stresses develop in the floor at these corners.Also these buildings are
more problematic due to the complex modes of vibration of their various
branches. The problem is further aggravated if the openings for stairs are located
at these locations, as shown in Fig. 3-1 (BSSC 1992a). Stair enclosures located near
the re-entrant corners are severely damaged in "E-shaped" New Hostel of Agri-
culture University.

Clearly, this building had a poor layout for its various modules and it suffered
from the lack of continuity between them as shown in Fig. 3-2. It is difficult to
remedy such plan deficiencies satisfactorily. However, its seismic performance
can be significantly improved by providing horizontal struts ("drag" members)

Figure 3-1. Damage to stair enclosures located near the re-entrant corners.

Jabalpur Earthquake of May 22, 1997 43