Finite-element analysis method to ensure the safety of invisible capping beams reinforced via the quick-replacement method

This paper presents a Finite-Element Analysis (FEA) method to solve the problem of reduced bridge safety due to insufficient durability of invisible capping beams. To reinforce a C30 invisible capping beam effectively and reasonably, a quick-repair replacement concrete reinforcement method was utilized, and the strength necessary for the appropriate admixture assessed. Specifically, the bearing capacity of the reinforced capping beam was studied via a single-point loading test, and the optimal replacement thickness required to install the beam within two days and restore normal operation within three days was determined using the non-linear software package MIDAS FEA. A finite-element model of equivalent size was employed using MIDAS FEA to obtain the deflection, tensile stress, and pressure stress at the boundary. The results indicate that C40 early strength concrete with 0.1–0.2% sodium gluconate admixture has the appropriate properties to achieve the target. It can be used to replace deteriorated concrete on the surface of invisible capping beams with a replacement rate of 30%. Further, to achieve the goal of resuming traffic within three days, the analysis results indicate that bilateral replacement with thickness 2 × 10 cm is optimal and the maximum replacement thickness should not exceed 2 × 20 cm.