Page 63 - Jabalpur_EQ

Chapter 3 Brick Masonry & Reinforced Concrete
Buildings

developing diagonal cracks. Figure 3-12 shows more severely cracked masonry
piers of the adjacent unit which might have disintegrated with a few more cycles
of loading. This is what happened to the next unit where masonry piers were lost
first, then the lintel beam resting on the masonry piers fell and, with the beam, all
spandrel masonry and part of the roof came down (Fig. 3-13).

Chandrika Homes, Amanapura

These two storey duplex apartment complex suffered heavy in-plane shear dam-
age to its brick masonry walls oriented along the North-South, the direction of
major shaking (Fig. 3-14). In-plane shear strength of masonry walls was consid-
erably weakened by the large openings for windows and doors. The disintegra
tion of masonry piers was so severe that in few cases the steel frame around the
door deformed, thus making the door unable to open and blocking the main exit
of the apartment. It is also believed that poor building material and quality of
construction used by the developer/builder attributed to such a poor perfor-
mance. In contrast, privately constructed similar URM buildings in the vicinity of
the complex performed much better. Mcreover, structures in this area appeared
to have subjected to an amplified ground motion as the site is located on a land-
fill.

Similar in-plane failures were observed at many other locations too as shown in
Figs. 3-15 to 3-20. In the Appendix, preliminary calculations show that the
masonry piers were subjected to tensile stresses even for the design level lateral
loads.

Figure 3-14. Severely damaged duplex units of a builder built Chandrika
Homes, Amanapura.

Jabalpur Earthquake of May 22,.1997 53