Abstract:The investigation into the causes of longitudinal and diagonal cracks in the bottom plate that appeared during the construction of a four-span prestressed continuous rigid box girder is presented. In order to propose preventive measures through on-site crack detection, temperature monitoring and finite element simulation analysis was adopted. The results of the bridge inspection demonstrate that the cracks are predominantly distributed at the joints of the segments and are accompanied by a discernible temperature rise effect. Utilising a thermodynamic coupling finite element model, it was determined that the temperature gradient resulting from the hydration heat of the concrete at the early age and the restraining stress were the primary causes of the cracks. The maximum local tensile stress in the base plate was recorded as 4.8 MPa, which exceeded the tensile strength of C55 concrete. The development of cracks can be effectively mitigated by optimising the arrangement scheme of the cooling water pipe. The research findings provide a theoretical foundation and an engineering reference point for the prevention and control of cracks during the construction period of similar bridges.
