Failure Conditions from Push-Out Tests of a Steel-Concrete Joint: Experimental Results

Abstract

Steel-concrete joints can suffer from premature fail due to inadequate shear bond between the two surfaces. In this paper the shear bond strength between steel and self-compacting concrete (SCC) without mechanical shear connectors is evaluated through push-out tests. The test samples consist of two sandblasted steel plates (10 and 6 mm) and a concrete core, with connection between steel and concrete obtained by a 2-component epoxy resin, gritted with granulates. During the tests, the ultimate shear force is recorded as well as the slip between steel and concrete. All test members exhibited a concrete - adhesive failure, and indicate nominal shear bond stresses between 2.20 and 4.22 MPa. In addition, a substantial difference in measured shear bond stresses is found between the 6 and 10 mm steel plates, indicating unwanted secondary effects with the 6 mm plates. During testing, maximum slip values between 0.02 and 0.05 mm are recorded. In addition to the experimental tests, shear stress distribution in the epoxy – concrete interface is examined by finite element analysis (FEA). In this way, a non-uniform stress distribution between steel and concrete is found with the maximum shear value about 2.5 times higher than the nominal shear stress value. The FEA combined with the experimental results provide a reasonable understanding of the shear induced failure conditions at a steel-concrete joint, and create test data for a fracture mechanics approach.