Stress transfer and fracture propagation in different kinds of adhesive joints

To effectively and efficiently utilize fiber-reinforced plastic (FRP) laminates (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 interfacial stress transfer behavior including debonding should be considered to be one of the most important effects on the composite structural behavior. In this paper, two kinds of nonlinear interfacial constitutive laws describing the pre- and postinterfacial microdebonding behavior are introduced to solve the nonlinear interfacial stress transfer and fracture propagation problems for different kinds of adhesive joints in FRP/steel-strengthened concrete or steel structures. Expressions for the maximum transferable load, interfacial shear stress distribution, and initiation and propagation of interfacial cracks (debonding) are derived analytically. In addition, numerical simulations are performed to discuss the factors influencing the interfacial behavior and the theoretical derivations are validated by finite-element analysis.