Design and Treatment Case Analysis of Continuous T-beam External Prestressed Composite Reinforcement Based on Finite Element Model Calculation

Abstract

The second section of a highway bridge is a 3×30m prestressed concrete continuous T-beam, of which the 5th span 4# T-beam was found to have multiple structural cracks, such as U-shaped cracks and vertical cracks, during regular inspections after one year of operation. Analysis has shown that this was attributed to the fact that the insufficient prestressing during construction caused inadequate prestressing in the beam body. In this sudy, Midas/Civil software is utilized to establish a spatial finite element model to estimate the loss of prestress in damaged T-beams, yielding results consistent with the inspected conditions. On this basis, an external prestressing reinforcement design plan is proposed. The innovative plan considers the impact of reinforcement on the hogging moment of continuous T-beams and optimizes the layout of prestressed steel strands. The layout and fixing methods of steel turning blocks and anchoring blocks are also optimized in accordance with the stress characteristics of continuous T-beams, with the bearing capacity and safety reserve improved. After checking and analyzing the crack width of the reinforced T-beam, it was found that the plan fully meets the requirements for prestressed concrete Class A components. According to plan, the damaged T-beam was repaired and reinforced, and continuous observation of the reinforced T-beam was conducted for two years. No new development of bridge defects was observed in the later stages, indicating a satisfactory reinforcement effect. This provides technical reference for similar projects.