Tensile behaviour of open-hole and bolted steel plates reinforced by CFRP strips

Abstract

Abstract The behaviours of the open-hole and bolted plates in tension are fundamental in the mechanical assessment of the bolted connections. Regarding the rehabilitation of steel structures, however, the combined effects of bolted washer clamp-up and CFRP reinforcement on the tensile behaviour of the connection with laser cut holes have not been fully understood. This investigation aims to fill the gap by carrying out experimental tests and developing analytical model accounting for these effects. The test results show that the CFRP reinforced plates are failed by the rupture of CFRP and the steel-adhesive interface failure accompanied by CFRP delamination. Both failure modes can be correlated with two load-deformation characterizing curves. It is also found that the increase of the nominal tensile strength of the specimens can be enhanced significantly by the increase of the number of the CFRP layers and further moderately improved with the combined effect of the bolted washer clamp-up. Moreover, the yield load and residual deformability of the specimens can be significantly increased with the bolted washer clamp-up and greater bolt torque respectively. An analytical model taking into account the bolt torque effect and interfacial stress equilibrium has been developed to predict the strength enhancement effects of washer clamp-up and CFRP reinforcement on the open-hole plates in different failure modes. The proposed model has been verified to be effective in providing satisfactory strength ratio in contrast to test data.