Experimental Evaluation Of FRP Strengthened Concrete Bridge Girders

This report presents the details of research study on the use of Carbon Fiber Reinforced Polymers (CFRP) sheets to strengthen the Pre-stressed concrete TxDOT Tx-28 bridge girders in flexure and shear. Four girders were subjected to destructive test in this research. First girder as control specimen without any CFRP applied on it, Second and third girders were flexural strengthened for one and two layers of CFRP and the forth girder is shear strengthened with one layer CFRP. Experimental phases along with the comparison of test results in terms of flexural and shear capacity of bridge girders, strains and deflections are discussed with reference to control and CFRP strengthened specimens.The CFRP strengthening was designed based on the ACI 440 recommendations. The report details the installation process as well as a load-testing program utilized to assess the effectiveness of the strengthening system. The installation process was found to be rapid and simple. The bonding between the FRP installed and the concrete surface is verified by pull off test, which ended up with the positive results in the bonding. Adding to this in order to monitor the strain and displacement, we had strain gages on the surface of FRP at the tension and compression zones of the girders and two transducers near the supports and two more transducers at the center. Good agreement was obtained with the experimental and theoretical findings of strength, strains and deflections. Overall, the strengthened girders behaved as predicted when subjected to the design loads. The detailed design of FRP strengthening is system is reported in this report.