Longitudinal Shear Behaviour Of Steel-Concrete Composite Slabs

Profiled steel sheeting-concrete composite slabs are widely used in buildings, due to their fast construction speed and high bearing capacity. The bearing capacity and rigidity of composite slabs are highly influenced by the slip between the steel deck and concrete slab. Because of this, the longitudinal shear failure may be in prior to the flexural failure for composite slabs when suggested to design load. In this context, this study aimed to quantitatively analysis the shear slip on the influence of bearing capacity of composite slabs by means of experimental study and finite element simulation. Three aspects of research work were done as follows:(1) Full-scale tests on the longitudinal shear behaviour of profiled steel sheeting-concrete composite slabsFor the purpose of studying the influence of shear slip between steel deck and concrete on the static performance of composite slabs, two full-scale slab samples cast on profiled steel decks with the slab depths of 120 mm and 180 mm were loaded to longitudinal shear failure. The distance between the roller supports is 2400 mm, and the width is 510 mm. The slab specimens were loaded with two third-point concentrate loads under simply supported condition. The experiment results show that the failure mode of these two specimens was typical longitudinal shear failure, and the ultimate bearing capacity was significantly lower than the calculated flexural bearing capacity. Besides, the partial shear connection(PSC) degree slightly increased with the depth of composite slab. The plain assumption was no longer available for composite slabs when the maximum strain was larger than 80% of the yielding strain of steel(i.e. external load being larger than 60% of the flexural capacity based on plastic design).(2) Finite element model(FEM) and its verificationBased on ABAQUS/Explicit, longitudinal shear finite element models were established. The combined effects of friction and mechanical occlusion between steel decks and concrete slab were modeled using Radial-Thrust. The FEM was benchmarked against the two specimens reported in this paper and one trapezoid profiled steel sheet composite slab with the depth of 150 mm in relevant literature. The load-displacement curves and load-strain curves obtained from FEM were compared with those obtained from experiments for validation purpose. Results obtained indicate that the benchmarking data(i.e. experimental results collected from this study and those available in literatures) were well predicted by means of using FEM and could be used for further study.(3) Parametric study and reference suggestions for design of composite slabsParametric study has been conducted using FEM on the key parameter of shear span ratio(i.e. λ in this study), which mainly influences the longitudinal shear behaviour of composite slabs. Eight models with different depths(i.e. 120 mm and 180 mm) and different spans(i.e. 2400 mm, 3000 mm, 3600 mm and 4200 mm) were established. Moreover, comparisons between FEM results and predictions of typical design methods for composite slabs were made in order to verify the applicability of the codes, and proper design suggestions were provided.