Strength of Fibre Reinforced Concrete Composite Slabs with Deep Trapezoidal Profiled Steel Decking

摘要

This thesis describes an investigation of the strength and deformation of steel fibre reinforced concrete composite slabs with deep trapezoidal profiled steel decking. An extensive experimental program has been conducted in which the effects of varying the steel fibre dosage on the strength, stiffness and ductility of single-span and two-span composite concrete slabs has been studied. The steel fibres used in this study were generally 60 mm long end-hooked fibres. A numerical finite element model has been developed and calibrated using the experimental data.Seventeen prismatic simply-supported composite slabs with deep trapezoidal profiled decking fabricated using either plain concrete or steel fibre reinforced concrete (SFRC), with fibre dosages of 30kg/m3 and 60kg/m3, were tested to failure and the shear-bond strength between the concrete and the profiled steel decking for each test specimen was evaluated. A finite element model developed using the software ABAQUS/Explicit has been presented and shown to accurately simulate the bond-slip relationship at the steel-concrete interface and the load carrying behaviour of single-span SFRC slabs. A model relating the shear bond at first slip to the tensile stress in the steel-fibre concrete is proposed and found to be a viable means for predicting the initiation of first slip between the decking and the concrete. The values of the maximum shear bond stress predicted by the numerical model were in reasonable agreement with the shear stress evaluated from the experimental results.A series of static load tests was also conducted on two-span composite slabs fabricated using either plain concrete or SFRC with fibre dosages of 20kg/m3, 30kg/m3 and 40 kg/m3. The finite element model is shown to provide good agreement with experimental results and to accurately simulate the behaviour of the two-span composite slabs over the full range of loading.The SFRC slabs showed significant and consistent improvements in the overall strength, the post-cracking stiffness and the load at first slip compared to the plain concrete slabs. The improvement in the shear-bond behaviour afforded by the steel fibres at the steel-concrete interface has been quantified and the steel fibres have been shown to be a viable replacement for the conventional reinforcement traditionally used in the negative moment regions of the two-span slabs.