Study On Mechanical Behavior Of FRP-Concrete Composite Structure

Fiber reinforced polymer/plastic (FRP) composites have become very popular in the few years. This has been due to the well-known advantages of FRP composites including high strength-to-weight ratio, high Young's-modulus-to-weight ratio, and high corrosion resistance. The composite structure of FRP and concrete is one of the most important fields of all fields that FRP composite is used. To the composite structure, it is very important to have good interaction between the concrete and FRP composite.The interaction between the concrete and FRP I-beam was obtained in two ways for the composite beam of FRP and concrete: casting in shear connectors of steel and bonding by epoxy adhesive. In this paper, a new form of composite beam is presented to utilize cementitiousness between cement colloid and FRP I-beam surface and frictional resistance between FRP I-beam and concrete as the interaction between the concrete and FRP I-beam. The composite beam consists of a FRP I-beam and the rectangular concrete block which FRP I-beam is encased in. Four composite beams have been investigated. These investigations indicate the plane cross-section assumption can be used in the composite beam and the interaction between concrete and FRP I-beam is satisfied before is up to 75%.In this paper, a special attention is paid on the peeling-off phenomena in FRP strengthening concrete beams. Based on beam theory and fracture mechanics, a new model is proposed for predicting the peeling-off behavior near the FRP-concrete interface, which is governed by residual thermal stress. Numerical examples are analyzed to give a clear insight into this failure mechanism. Some suggestions are provided to optimize the design of strengthening structures.To effectively utilize fiber reinforced plastic (FRP) plates (or sheets) in strengthening civil infrastructures, a design strategy integrating the properties of FRP reinforcement and composite structural behavior needs to be adopted. The bridge stresses behavior should be considered to be one of the most important effects on the concrete beam strengthened by FRP. Their behaviors are introduced to solve the nonlinear interfacial stress transfer and fracture propagation problems for mechanical character of FRP strengthened concrete beam. Expressions for the driven force, the resistance and the slope of them are derived analytically. In addition, numerical simulations are performed to discuss the factors influencing the interfacial and theoretical derivations are validated.In conclusion, the interaction between the concrete and FRP needs to be emphasized, when mechanical behavior of FRP-concrete composite structure is studied.