Strengthening Full-Scale Damaged Precast/Prestressed Concrete Double-Tee Girders Using CFRP Sheets

Abstract

Canada is facing a major crisis with the deterioration of its infrastructure (bridges, harbours, buildings, water structures, sewers, parking garages, etc.). Many of these structures were build using precast prestressed concrete members. These members may be under-strength because of deficiencies in design, increase in applied loads, loss of prestress, or damage due to the effects of corrosion, collision or military operations. Epoxy-bonding composite materials to the tension side of prestressed concrete girders is an effective technique for shear/flexural rehabilitation and strengthening of such members. To ensure successful and cost-effective applications of such materials, engineers need to improve their knowledge with respect to the actual behavior of full-size girders so that they can gain confidence on using these materials on structural strengthening and rehabilitation. This can be achieved by providing more data on testing-to-collapse and on field conditions full-scale prestressed girders strengthened using FRP materials. This study details the use of Carbon Fiber Reinforced Polymer (CFRP) Sheets to repair and strengthen precast presetressed concrete Double-Tee (DT) girders in flexure and shear. Three actual-size partially-damaged DT precast pretensioned girders were obtained from the manufacturer. All three of the girders were repaired and strengthened, and then tested to failure to determine flexural and shear capacities. The stems of two of these girders were strengthened in flexures using U-shape un-directional carbon fiber reinforced polymer sheets (CFRP), extending from the mid-span to the quarter points of the girders. Two girders were strengthened in shear the dapped ends using 0° wrapping technique around the stem, while the dapped ends of the third girder were strengthened using 0°/90° wrapping technique. Each girder was loaded incrementally up to failure using Jersey Barriers. This project summarizes the loading history and reports test results that can be further used to demonstrate the practicality of girder strengthening with CFRP sheets in field conditions.