Push-out tests for shear connections between UHPFRC slabs and FRP girder

This paper presents an experimental investigation on the shear connections between carbon/glass Fiber-Reinforced Polymer I-girder and Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) slabs. Effects of straight/inclined bolt shear connectors and effective embedment depth-to-bolt diameter (hef/d) ratios were investigated. Fourteen push-out tests were conducted to evaluate the load-slip behavior and the ultimate resistance of the bolt shear connectors. With the use of the UHPFRC, the hef/d ratio needed for obtaining a shear connector failure mode was 2.7 times lower than that obtained from 43 push-out tests in the literature for normal weight and lightweight concrete slabs. The inclined bolt shear connectors showed a more ductile behavior than the straight bolt shear connectors. The experimentally obtained ultimate resistance of the bolt shear connectors was compared against the equations provided by ACI 318-11, AISC 2011, AASHTO LRFD 2010, PCI 2004, and EC-4 2004. An empirical equation to predict the ultimate shear connector resistance was proposed and validated by the experimental data. Idealized load-slip models and equations to predict the load versus slip relationship for all push-out tested specimens were proposed. Curve fitting was performed to find fitting parameters for all tested specimens and the results showed a very good correlation with the experiments.