Unified Analysis and Design Approach for CFRP Prestressed Concrete Bridge Girders

摘要

This paper presents an analysis and design approach for carbon fiber reinforced polymer (CFRP) concrete bridge girders prestressed using bonded pretensioning and unbonded post-tensioning tendons arranged in multiple vertically distributed layers along with non-prestressing CFRP rods. Design equations to determine the flexural capacity of the prestressed concrete bridge girders are provided. In addition, based on parabolic stress-strain relation for concrete and linear stress-strain relation for tendons, a computer program was developed to compute the overall response of the beams such as deflections, strains, cracking loads, and post-tensioning forces. Comparing the analytical results with experimental results from a full-scale Double-Tee (DT) test beam validated the design equations and the accuracy of the nonlinear computer program. The difference in the analytical and experimental values of the ultimate moment capacity of the DT-test beam is negligible. A detailed parametric study was conducted to examine the effect of the level of prestressing forces on the deflections and ultimate load carrying capacity of the full-scale DT-beam. It was observed that the combination of bonded and unbonded prestressing levels (0.3 to 0.6) can significantly increase the ultimate moment capacity of the beam.