Shear Performance of Full-Scale Prestressed Hollow-Core Slabs Reinforced by Local Grouting from the Bottom of the Shear Span Region

As the prestressed hollow-core slab (PHCS) bridge is usually constructed with adjacent configuration between each component along the transversal direction, the closely connected webs significantly limit the operational space for shear reinforcement. To solve this problem, a bottom-up localized grouting reinforcement method was proposed to fill the cavities in the shear span region. This method involves drilling holes in the bottom slab, followed by installing pipes and localized grouting to cover the shear span region. Six full-scale specimens, with a longitudinal span of 16 m, with different grouting forms were tested under shear loading to investigate the reinforcing effects. The test results indicate that the shear bearing capacity of the reinforced specimens increased by 8.7%–20.4%, with compressive strain at the top and tensile strain at the bottom reduced by 11%–45%. In addition, numerical models were established to systematically analyze the influence of the shear span ratio and grouting length. The grouting length was recommended to be 1.5 times the shear span length to balance the reinforcement performance and cost. Finally, based on experimental and simulation results, a predicting method was proposed to calculate the shear bearing capacity of the PHCS with proposed grouting reinforcement. The prediction showed acceptable agreement with experimental results based on the average value, standard deviation, and average absolute error of 0.969%, 0.047%, and 4.86%, respectively.