Residual Capacity of Mainshock-Damaged Precast-Bonded Prestressed Segmental Bridge Deck under Vertical Earthquake Ground Motions

Abstract

Although the use of segmental bridge decks has increased around the world, their use in seismic regions under vertical earthquake motions is yet to be fully understood. The asymmetric behavior of segment joints under vertical motions as well as the low strain ductility of cables passing through the joints raise questions on postearthquake performance of decks following a disastrous earthquake and during aftershocks. Because strong aftershocks can expedite the collapse of structures damaged in the mainshock, assessing the residual capacity of mainshock-damaged bridges becomes important with regard to postearthquake performance. In the current research, two medium- and long-span case study bridges were investigated to study the residual capacity of bridges of such type. To this end, a two-dimensional model for segment joints was developed and verified via experimental results. The results related to nonlinear time-history analysis under the design earthquakes showed that midspan segment joints were bound to suffer spalling concretes at the bottom and yielding tendons at the top. The findings revealed that the residual capacity of the mainshock-damaged bridges decreases with the increase in the damage level caused by mainshock, yet not more than 5% in comparison to the intact bridge, even at the worst damage level.