Interfacial behavior of mechanically anchored FRP laminates for strengthening steel beams

This study investigates the response of FRP–steel anchored lap connections along with the associated interfacial behavior. The investigation is conducted experimentally and numerically. The experimental program includes testing of eighteen short specimens to explore the influence of sheared edge distance and rolled edge distance on the load carrying capacity and ductility of the assembly. In addition, six longer connections are tested to assess the effect of the spacing between bolts on the response. The findings suggest a sheared edge distance of about six to seven times the bolt hole's diameter. The effect of the rolled edge distance values considered in the study on the performance of the connections is found to be insignificant. A non-linear load–slip model is proposed to simulate the interfacial behavior of the assembly. A finite element study is conducted using an equivalent non-linear spring element to simulate the interfacial behavior based on the proposed load–slip model. The excellent match between displacement and strain responses measured experimentally and their numerical predictions validates the accuracy of the proposed load–slip model. The flexural behavior of two full-scale I-shaped steel beams is then investigated experimentally to explore the enhancement in the response of beams strengthened with mechanically anchored FRP laminates. Finally, a finite element model is utilized to predict the elasto-plastic response of the tested steel beams. The excellent agreement between the numerical predictions and experimental measurements provides another validation for the proposed load–slip model. ► Experimental results of 24 FRP–steel anchored lap connections are presented. ► Test outcomes reveal ductile response of FRP–steel anchored connections. ► The influence of edge distance and bolt spacing on response is also explored. ► A non-linear load–slip model is developed for FRP–steel anchored connections. ► The load–slip model characterizes the interfacial behavior of such connections.