Civil Engineering Reference
In-Depth Information
Figure 7.16
Temporary fi xity of deck built span-by-span
creep, shrinkage and temperature change, but lock up under the effects of acceleration/
braking or seismic forces.
An example would be a railway bridge on very tall piers. The deck may well be
fi xed onto some of the piers, with sliding bearings on the others and on the abutments.
Thus effects of differential friction would be shared between several piers, as described
above. However, under the effect of a train accelerating on one track and braking on
the other, the columns providing deck fi xity may be too fl exible, allowing excessive
longitudinal movements. If shock absorbers were to be attached between the bridge
deck and one of the abutments (or both abutments), these sudden forces would be
carried rigidly by the abutment, Figure 7.17 (a).
