Structural and Operational Safety Evaluation of a Long-Span Continuous Beam Bridge with an Excessive Deflection in Urban Rail Transit | Journal of Performance of Constructed Facilities | Vol 37, No 2

AbstractPrestressed concrete continuous beam bridges often experience increasing deflection during operation, affecting service performance. However, the evaluation method of continuous beam bridges with an excessive deflection in urban rail transit still needs to be improved. This paper carried out a structural and operational safety evaluation of a long-span continuous beam bridge with an excessive deflection in urban rail transit. Long-term deformation monitoring, static load tests, and natural frequency tests were conducted to evaluate the structural property development and response under the train loading. Based on the field data, a train–track–bridge coupled numerical model was established and calibrated to analyze the dynamic deflection, acceleration of the bridge, train safety, and comfort indexes. Subsequently, the deflection limits and maintenance schedule were discussed. The results show that the bridge exhibited a deformation curve with a large midspan deflection and a slight side-span camber. The cumulative static deflection of the midspan was 50.4 mm since the beginning of long-term deformation monitoring. The increasing deflection led to the gradual reduction of elasticity recovery capacity (ERC), but ERC remained at a high level and there was no significant attenuation of the structural stiffness. The evaluation methods proposed in this paper can provide useful references for the management of similar long-span continuous beam bridges in urban rail transit.

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