Shear response and evaluation of pultruded FRP-concrete push-outs

In this paper, an investigation aimed at characterising the behaviour of headed shear studs in a push-out testing is presented. The study involved two phases of push-out tests on composite slabs. Phase one focused on studying the effects of headed shear stud configuration on the load capacity of the composite slabs, adopting 19 mm diameter headed shear studs in a single-row, double-row and staggered configurations. Phase two of the study was aimed at characterising the behaviour of the composite slab by varying the headed stud diameters. Two push-out test specimens adopted 12 mm diameter studs. The other two specimens were manufactured using 16 mm and 19 mm diameter studs. Push-out capacity up to 552.7 kN was recorded. There was a correlation between the diameter of studs and push-out capacity. The mode of failure observed was consistent across all specimens tested. The dominant failure mode was bearing, net tension and shear out failures of the FRP plates. These modes of failure were distinctly different from those prevalent in conventional steel-concrete composite which is either stud shank failure and/or concrete pull out. The composite behaviour was also studied analytically. The experimental shear strength of 16 mm diameter studs was in close agreement with that predicted using Eurocode 4. The experimental shear strength of 12 mm and 19 mm diameter studs varied significantly from the code predictions. The specimen with 16 mm studs attained higher shear strength per stud, approximately 10.5% in comparison to those with 12 mm diameter headed studs. The current study is compared to results found in the literature and would form the basis for developing full-scale concrete-FRP composites beams.