Mechanical properties of constitutive parameters in steel–concrete interface

Mechanical properties of steel–concrete interfaces are evaluated on the basis of three existing experimental evidences. The properties include bond strength, unbonded and bonded friction parameters, residual level of the friction parameter, normal fracture energy release rate, bonded and unbonded slip fracture energy release rates under different levels of normal stress, and shape parameters defining the geometrical shape of the failure envelope. For this purpose, a typical type of constitutive model for describing steel–concrete interface behavior is presented based on a hyperbolic three-parameter failure criterion. The constitutive model depicts the strong dependency of interface behavior on bonding condition of the interface, bonded or unbonded. Mechanical roles of the interface parameters are discussed with reference to those of the presented interface constitutive model. Values of the interface parameters are determined through interpretation of existing experimental results, geometry of the failure envelope and sensitivity analyses. These values are applied to push-out tests of concrete-infilled rectangular steel columns with three different cases of interface lengths. The failure process of concrete-infilled rectangular steel columns is discussed through comparison of experimental measurements with numerical results.