Page 103 - Jabalpur_EQ

Chapter 6
Lifelines

Figure 6-8. Undamaged aqueduct cum road bridge over the river Narmada on
NH 7 at Tilwaraghat

Aqueduct cum Road Bridge over the Narmada River

Recently constructed aqueduct cum road bridge on NH 7 over the Narmada river
did not show any indication of damage (Fig. 6-8). The aqueduct structure is a part
of the multipurpose Narmada River Valley Development program.

Railway Bridge over the Narmada River

A meter gauge railway bridge on the Narmada river suffered damage to its
rocker supports when pins either slipped out of the bearing or fractured. The pin
in the roller and rocker bearings were fractured at several supports and the gird-
ers were displaced transversely by about 100 mm. Fractured pins were replaced
and the bridge resumed its normal traffic in about two days.

An investigating team from IITK and IITB estimated that the peak acceleration at
the top of piers may have exceeded 0.4g. The lateral transverse load on a span was
to be resisted by four 32 mm pins of mild steel with tensile strength of about 20
tons each. The weight of the superstructure span was estimated to be about 200
tons (Jain et al. 1997). This estimate of peak acceleration agrees with those
described earlier in Chapter 1.

Jabalpur Earthquake of May 22, 1997 93