| Structural applications of fiber reinforced polymer (FRP) composites have recently gained much attention in the civil engineering community due to their superior material properties (e.g., high specific stiffness and strength, and high corrosion resistance). However, all-composite structural systems have specific shortcomings such as high initial costs, low stiffness, and existence of catastrophic failure modes.; To create a superior structural system that makes the best use of materials, a hybrid construction of FRP composites with concrete was investigated in this study for bridge superstructure applications. The proposed hybrid FRP-concrete bridge superstructure consists of trapezoidal glass fiber reinforced polymer (GFRP) box beams with a thin layer of concrete placed in the compressive zone. The concrete layer prevents a compressive GFRP flange from buckling, reduces the local deformation under concentrated loads, and increases the system flexural rigidity. Webs of the box section were designed at an incline to have better interactions and to reduce shear force between sections.; The objective of this study was to investigate the feasibility of the proposed hybrid FRP-concrete bridge superstructure. As a trial case, the bridge was designed as a simply-supported single span one-lane bridge with a span length of 18.3 m. Geometrical parameters of the proposed system were determined by using the detailed finite element analysis (FEA). Performance of this hybrid bridge superstructure was examined both experimentally and computationally. A test specimen, fabricated as a one-fifth scale model of the prototype bridge, was subjected to a series of loading tests: nondestructive tests (flexure and off-axis flexure), destructive tests (flexure, shear, and bearing), and fatigue test. Nonlinear material models of both concrete and GFRP were successfully incorporated in the FEA to examine inelastic behavior of the hybrid bridge.; Results from both the experiment and the FEA demonstrated excellent performance of the hybrid bridge under AASHTO design loads. The experimental results also demonstrated that the bridge has significant reserve strength and excellent fatigue behavior.; Design procedures and simple methods of analysis were also proposed in this study. It was found that the simple methods of analysis could accurately predict the behavior of the hybrid bridge under various loading conditions. |
