Deflection Control of Long-Span PSC Box-Girder Bridge Based on Field Monitoring and Probabilistic FEA

For long-span prestressed concrete (PSC) box-girder bridges, excessive midspan deflection because of uncertain concrete shrinkage and creep undermines driving comfort and structural safety. In this paper, a deflection control strategy is proposed on the basis of field monitoring and probabilistic finite element analysis (FEA). The time-dependent behavior of the bridge was predicted using a three-dimensional finite element model with integrated time-dependent models for creep and shrinkage. The FE model was validated or updated according to field monitored data to predict future bridge performance. Using probability density functions of variables and probabilistic analyses, uncertainties in long-term deflections were described. Finally, according to the probabilistic analysis results and the allowable deflection, the amount for deflection control was determined, and the control was conducted using backup prestressing tendons. A case study on the Jinghang Canal Bridge, a three-span continuous PSC box-girder bridge in China, was made for demonstration.