CRASHWORTHY DESIGN OF CONCRETE HIGHWAY BRIDGE RAILING REINFORCED WITH ADVANCED COMPOSITE BARS

摘要

The use of fiber reinforced polymer (FRP) bars as internal reinforcement for concrete is a viable option for the construction of concrete bridge decks and railings, especially in areas where corrosion of steel reinforcement is of most concern. Design principles for FRP reinforced concrete (RC) are well established that reflect the peculiar physical and mechanical properties of the reinforcement materials. As design codes become effective or are being developed, this technology is making the transition from research to commercial projects. In bridge construction, open-post concrete railings are often preferred due to aesthetic, functionality, and safety characteristics. Crash testing of new systems is typically mandated, as in the case of the AASHTO LRFD specifications. However, design approaches for steel RC test specimens are not applicable to indeterminate FRP RC systems. In this paper, a methodology for the structural design of FRP RC open-post railings is presented where internal forces, deformations, and failure mode are explicitly determined. The methodology is then demonstrated for the case of a highway bridge railing, which is designed to resist the code-mandated equivalent static load. The structure is shown to meet the transverse strength demand while undergoing very small deformations, which is typical of crashworthy RC railings.