Longitudinal Shear Behaviour Of Flat Profile-concrete Composite Slabs With End Studs

Composite steel-concrete slabs show their advantages in various structures due to their high bearing capacities and fast construction speed.The ultimate limit state for composite slabs with common design parameters can be controlled by the longitudinal shear capacity despite that their flexural capacity is mainly the controlled criteria.For structures adopting composite beams,the studs at the end of composite slabs supported by steel beams contribute to the longitudinal shear behavior of composite slabs,however,quite limited research on the influence of studs on the longitudinal shear behavior has been conducted and current design procedures need to be further benchmarked.In this context,experimental investigations were conducted on the bond behavior of composite slabs cast on flat profile,and the influence of studs on the longitudinal shear behavior was quantified based on full-scale tests and finite element analysis.The main work is presented as follows.(1)Push-out test study on the longitudinal shear behavior of composite slabsPush-out test was conducted on 3 groups of composite samples(two identical in each group)cast on flat profiles with dimensions of 510mm×510mm×120mm,based on which the reliability of the proposed self-equilibrium test system using U-shape plate was verified and the test setups of “two samples connected back to back vertically” and “one sample laid horizontally” were compared.Based on the experimental results,a reliable push-out test setup was proposed for composite slabs,and the bond-slip curves were obtained for composite slabs cast on plate profiles.(2)Full-scale test study on the longitudinal shear behavior considering the influence of end studs2 full-scale composite slabs cast on flat profiles with a span of 3000 mm were tested to failure under four-point loading conditions.One sample was designed with end studs,while the other one was prepared without end studs for comparison purposes.The failure modes,load-deflection curve,end slip and strains on the mid-span and shear spans were obtained to investigate the influence of end studs on the longitudinal shear behavior.The test results show that the longitudinal shear capacity of composite slabs was improved by 39.7% due to the end studs.(3)Finite element analysis of the longitudinal shear behavior of composite slabsFinite element models were proposed for composite slabs cast on open trough profile and flat profile by means of ABAQUS software,and the bond behavior was simulated using Radial-Thrust connection elements and the influence of end studs on the longitudinal shear behavior were simulated by solid elements and corresponding interactions.The proposed FEM were benchmarked through a comparison between FE results and experimental data with the differences in the ultimate capacity of 2.5%~3.5%.A parametric study was then carried out,and the influence of shear span ratios,composite slab depths,stud dimensions and depths on the longitudinal shear behavior were obtained.The applicability of current design procedures recommended by EC4 was verified through a comparison between code predictions and FE results.