Reinforced concrete and steel have been used as the main construction materials for medium-to long-span bridges over the several decades. However, deterioration of reinforced concrete and corrosion of steel structures have become one of the important issues of bridge structures. In recent years, many new advanced composite materials have been proposed to use and replace probably the conventional construction materials, as shown by both research findings in the areas and practical applications.

Fibre reinforced plastic (FRP) composites possess excellent engineering properties, including low density, high strength and high stiffness as well as chemical resistance. These properties, together with the recently reduced material cost-to-weight ratios, encourage the use of advanced FRP...[ Read more ]

Reinforced concrete and steel have been used as the main construction materials for medium-to long-span bridges over the several decades. However, deterioration of reinforced concrete and corrosion of steel structures have become one of the important issues of bridge structures. In recent years, many new advanced composite materials have been proposed to use and replace probably the conventional construction materials, as shown by both research findings in the areas and practical applications.

Fibre reinforced plastic (FRP) composites possess excellent engineering properties, including low density, high strength and high stiffness as well as chemical resistance. These properties, together with the recently reduced material cost-to-weight ratios, encourage the use of advanced FRP composite materials in civil engineering structures, such as bridges and buildings, and provide significant advantages over conventional materials for infrastructure applications.

In this research, FEM simulations are conducted which are carried out on a micro-scale and then a meso-scale through a damage constitutive model of FRP composite laminates, and finally for the structural analysis of FRP composite bridge decks on a macro-scale. In the micro-scale study, 2D micro RVE models are used for investigating the mechanical behaviour of FRP composite subjected to transverse tension, transverse compression and out of plane shear. The 3D micro RVE models and the 3D beam models are proposed for studying the mechanical behaviour in the in-plane shear case and for analysing the micro buckling of FRP composite under longitudinal compression, respectively. From the energy dissipation during the loading history and the distribution of damage and plastic strains, it is found that either interfacial damage or matrix yield can cause the nonlinear deformation and then final failure. The longitudinal compressive model shows the micro buckling of the fibres and the formation process of kicking band.

A damage-plastic constitutive model which considers both damage and yielding is developed based on the micro-scale simulations for the analysis of the mechanical and nonlinear behaviour of FRP composite laminates. It is assumed in the proposed model that damages are mainly caused by interfacial debonding and that the interfacial damage is independent of the matrix plastic deformation by ignoring the plastic strain caused by interfacial cracking, and vice versa. All the parameters in the model are obtained from the micro simulations. This damage-plastic constitutive model of FRP composite has been implemented in VUMAT which is a material subroutine of ABAQUS Explicit. It is found that the analysis results of the damage-plastic model agree well with those from the micro simulation under different loading conditions.

The proposed damage-plastic constitutive model is further applied to the simulation of FRP bridge decks and bolt connections. This model keeps the major nonlinear characteristics in the micro-scale simulation. It is indicated that the meso-scale FEM simulations save computation time significantly as compared with those of multi-scale FEM. The deck with the [0/45/90/-45/0]_s orientation, which fails in bending, is shown to prossess the highest load-carrying capacity and stiffness. A cable-stayed bridge with an FRP composite girder is designed based on the Kap Shui Mun Bridge for preliminary studies. Shaking table tests show that the dynamic performance of the CFRP bridge is better than that of the prototype steel bridge.