Influence of vertical earthquake motion and pre-earthquake stress on joint response of precast concrete segmental bridges

摘要

>Segmental construction of precast concrete bridges can accelerate construction and minimize the cost in highly congested urban environments, environmentally sensitive regions, difficult-to-access ravines, and wide rivercrossings where medium-sized to long repetitive spans are needed. Despite their proven benefits, precast concrete segmental bridges experience limited use in seismic regions of the United States. A main obstacle to their use is concern regarding the seismic response of segment joints. This paper investigates the seismic response of precast concrete segmental bridges using detailed, two- dimensional, nonlinear time-history analyses and focuses on the behavior of segment-to-segment joints constructed using the balanced-cantilever method. Analytical models of full-scale precast concrete segmental bridges with geometries and characteristics similar to the Otay River Bridge in California were used in this study. Twenty near-field earthquake records were used to determine the median joint response as well as to quantify the effect of vertical motion on the joint response. Four different pre-earthquake stress conditions were studied to determine whether the effects of creep, shrinkage, and temperature affect the seismic response of segment joints. Results indicated that vertical earthquake motions and the pre-earthquake stress state can significantly alter the response of segment joints.