Comprehensive Study on Using Externally Bonded FRP Composites for the Rehabilitation of Reinforced Concrete T-Beam Bridges

摘要

This paper describes a synthesis of findings pertaining to rehabilitation of concrete T-beam bridges with externally bonded fiberreinforced polymer (FRP) composites from a Pennsylvania Department of Transportation District 3 (PennDOT D3) project, with the purpose of answering common questions of concern mainly by state DOT engineers and officials. A method for selecting applicable candidate bridges for suitability of repair with externally bonded FRP composites is described. Three levels of repair are identified, Level 1 (contract), Level 2 (contract/department force), and Level 3 (department force). From this classification, a candidate bridge was selected for a contract repair project. Field and laboratory testing of existing bridge materials is described. Prerepair tests included ultrasonic pulse velocity and rebound hammer on beam concrete, compressive strength tests on deck concrete cores, carbonation tests for both beam and deck concrete, scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) analyses for beam and deck concrete, and tension tests of the extracted reinforcing steel. Structural analysis was on the basis of AASHTO specifications. Finite-element (FE) modeling was performed to determine existing capacity, and the FE model was calibrated by testing of the bridge by using applied truck-loads. The FRP design was based on strengthening the bridge to sustain an HS-20 AASHTO truck loading. The FRP-repair system was designed on the basis of current American Concrete Institute design guidelines. Repair work and post construction load testing were completed. Supporting full-scale lab studies were conducted to evaluate the most effective concrete substrate repair method and FRP strengthening scheme for laboratory damaged concrete beams by accelerated corrosion, to assure better long-term performance under static and fatigue loads. Results from the rehabilitated bridge and supporting testing were used to develop draft PennDOT design standards and construction specifications and to apply lessons learned to the design and constructability of nearly 1,000 concrete T-beam bridges in Pennsylvania.