Monitoring and Simulation of Long-Term Performance of Precast Concrete Segmental Box Girders with Dry Joints

摘要

Precast concrete segmental (PCS) box girders are popular in bridge construction, although structural deterioration due to creep and shrinkage has been a concern. In contrast to the extensive studies on shear and bending behaviors of PCS beams, investigation on the long-term performance of PCS box girders is limited. In this study, six PCS box girders with dry joints were loaded inside a laboratory for 1 year, and ambient temperature, relative humidity, prestress loss, concrete strains, and time-variant deflections were monitored to investigate the long-term performance of PCS box girders under multiple factors. Numerical simulation was performed, where the variation of ambient factors was taken into account, and a good match between simulated and test results was observed. Based on laboratory observations and numerical simulation, it was found that shorter concrete age at loading, lower concrete strength, fewer segments, smaller reinforcement ratio, more shear keys, higher initial prestress, and larger external load resulted in more significant structural deterioration, including the loss of prestress and increasing deflection. According to the numerical simulation, the loss of prestress along the girder was complex and influenced by the change in cross section, location of shear keys, and tendon shape.