Numerical analysis of bridge deck rehabilitation by ultra-high-performance concrete (UHPC) overlay

Abstract

Abstract Rehabilitating the deteriorated deck of post-tensioned concrete box-girder bridges by ultra-high-performance concrete (UHPC) overlay is studied in this paper. Three post-tensioned concrete box-girder bridges in California were selected for the deck overlay analysis. Rehabilitation construction procedures for each bridge were described, including the practical lane closure and traffic re-routing. Detailed finite element models were established incorporating the staged construction modeling of the rehabilitation process, the time-dependent properties for existing concrete and prestressing tendon, and a “double-layer” modeling technique for the simulation of the deck. The time-dependent curves and equations of a specified UHPC were fitted based on experimental data, including creep, shrinkage, and elastic modulus, and this particular mix has been assumed in the FE analysis. How the thickness of the deck layer to be replaced affected the stress distributions in the UHPC overlay and the existing box girder was parametrically studied. Results indicated that stress variations in the existing box-girder were acceptable during the deck rehabilitation construction, but significant tensile stresses were developed in the newly placed UHPC deck overlay. Shrinkage-mitigation measures, such as adding the shrinkage-reducing admixture (SRA), should be considered during the placement of the UHPC overlay to control the shrinkage-induced tensile stress. Steel reinforcement may be adopted in the negative bending moment region to resist the flexural tensile stress by the live loads. The rehabilitation thickness of 3.8–5.1\xa0cm (1.5–2.0\xa0in.) is deemed appropriate for the bridges selected in this study.