Experimental and Nonlinear Finite Element Analysis of Double Skin Beam-Column Joints

The Double Skin Composite (DSC) or Steel-Concrete-Steel (SCS) elements (beams, slabs and columns) have been subjected to intensive studies during the last three decades. Member beam, column and slab have been studied under monotonic, cyclic and fatigue loading, and there are also a few studies on impact loading to assess the structural response of such constructions. Validating connectivity between the DSC beam and DSC columns is behind the usage of such constructional systems since all the present studies focus on individual members. The main objective of this thesis was to introduce the Double Skin Composite (DSC) beam-column joint as a new structural element. Experimental investigation and Nonlinear Finite Element Modelling (FEM) of the structural behaviour of the DSC joint subjected to monotonic and quasi-static loading was introduced. Five DSC joints have been tested to assess the efficiency of the DSC beam-column joint in its basic design and to identify the most efficient strengthening method. Further, six DSC beam-column joints were tested to study the effect of steel fibre (SF) and the effect of high-strength concrete (HSC) on the behaviour of the joint under monotonic loading and under cyclic loading. The general FE Package ABAQUS 6.10 was used to model the nonlinear behaviour of the DSC joint. The Concrete Damage Plasticity Model (CDPM) was used to model the concrete in tension and compression, and the steel elements of the composite were modelled using the elastic-plastic model. The model was validated against the experimental result and showed good agreement in predicting the maximum load and the general behaviour with a deviation of 10% or less. The examined strengthening methods showed improvement in the ultimate load capacity of between 517% and 871%. SFC and HSC provided the best performance in increasing the ultimate load and moving the location of the plastic hinge away from the face of the column. The validated FE model was used to conduct a parametric study to investigate the effect of the concrete compressive strength, shear stud connector spacing to steel plate thickness ratio, and the stud diameter to steel plate thickness ratio. The parametric study findings were in good agreement with experimental observations such as that the concrete compressive strength had a significant effect on the joint shear resistance and ultimate load.