Waiting Period for Closure Pours in Bridge Widening or Staged Construction: Fid-Bau Portal

Waiting Period for Closure Pours in Bridge Widening or Staged Construction

Chai, Y. H. / Hung, H. J.

Current practice in California requires up to a 60-day waiting period for closure pour after falsework release for both staged construction and bridge widening. The relatively long waiting period is intended to mitigate damage to the connected bridge deck as differential displacement develops between the new and previously constructed decks. The current waiting period does not take into account the displacement capacity of the closure slab, which depends on the dimensions and reinforcement details of the slab. In this paper, time-dependent deflection of two bridges under construction was measured up to approximately 12 months, and full-size tests were conducted to investigate the behavior of closure slabs when subjected to differential displacement. The objective of the tests was to determine the deformation capacity of the slab so that time-dependent deflection of the bridge can be directly taken into account when determining the waiting period for slab closure. Parameters in the test program included the length and thickness of the slab and the use of couplers in the slab reinforcement. Results indicated that attention needs to be paid to large stiff closure slabs, leading to a long waiting period, as brittle failure may occur at relatively small differential displacement.