The effects of bond and anchorage on the behaviour and design of composite slabs

Composite steel-concrete slabs represent a popular form of flooring system in high rise buildings and bridges. This thesis comprises of experimental studies and numerical analyses into the behaviour of post-tensioned composite slabs and composite slabs with end anchorage. The shear bond between the profiled steel sheets and the concrete is very crucial to the behaviour and strength of post-tensioned composite slabs. Therefore, the possible influence of prestress on this bond behaviour is a fundamental issue for these types of slabs. In this context, a series of push tests incorporating post-tensioning at the steel bar to apply precompression to the concrete were conducted. The test results indicated that the prestress has a detrimental effect on the bond between the profiled steel sheets and concrete in post-tensioned composite slabs.This research study developed a three dimensional nonlinear finite element model of a post-tensioned push specimen using ABAQUS to simulate the bond stress-slip relations accurately. The bond stress-slip relations obtained from push tests were then assessed for post-tensioned profiled composite slabs numerically. A parametric study was conducted using the verified finite element model to study the effects of concrete strength, level of prestress, and thickness of the profiled steel sheets on the overall performance of this type of slabs.The end anchorages in combination with other shear transfer mechanism play an important role into the strength, stiffness and ductility of composite slabs. A series of tests were carried out on solid and profiled composite slabs under restrained and unrestrained conditions. The test results showed that end anchorages have a positive effect on the ultimate strength of both solid and composite slabs irrespective of the long term loading conditions. A three-dimensional finite element model is developed to simulate the behaviour of composite slabs with end anchorage. A parametric study was conducted to investigate the influence of concrete strength, shear stud strength and profiled sheeting thickness in profiled composite slabs. In general, the findings of the experimental studies and numerical analyses presented in this thesis herein are expected to be contributing a further knowledge to the continuing improvement of composite steel-concrete structures