| Partially Encased Concrete Composite(PEC)structure is a novel type of composite structure with a late development.The basic form of this type of composite structural section is that concrete is filled in the opening section of the steel member.Besides,according to the practical application requirements,additional components as known as steel tie rods,can be selected to improve the structure performance.Among all PEC structures,PEC columns are the most widely used as load-bearing component.In addition to the many advantages of conventional steel-concrete composite structures,PEC columns have also been improved in terms of steel fire resistance,corrosion resistance,and prefabricated assembly efficiency.At the same time,with the increasing diversification of building structural forms,the traditional square column system can no longer meet requirements for building aesthetics and seismic performance.In this context,therefore,as the special-shaped PEC column,especially the cross-shaped PEC column,which can construct a non-convex column system,it has been gradually applied to practical building structures.However,the systematic research on the crossshaped PEC column in China is insufficient,and its working mechanism and mechanical properties need to be solved urgently.In this study,the compression performance of the cross-shaped PEC short column is deeply studied with experimental research,numerical analysis,theoretical research,etc..Within the scope of this study,the following are the specific research contents and results:(1)The experimental study on the axial compression performance of 6 cross-shaped PEC stubs was conducted.The influences of some key parameters such as steel content,tie rod spacing and section length-width ratio were measured.It demonstrated the failure mode of the cross-shaped PEC stubs under axial compression and the influence of above-mentioned parameters on mechanical properties of short columns.(2)This study also conducted numerical study of the axial compression performance of the cross-shaped PEC short column by using ABAQUS finite element analysis software.Then the constitutive relation of the confining concrete of the cross-shaped PEC short column was proposed,and experiment was established to validate the finite element model.Moreover,the influence of parameters including steel content,steel strength,tie rod spacing,concrete strength and section length-width ratio on the axial compression performance of the cross-shaped PEC short column were explored for the further study,and the mechanics mechanism of the whole process was analyzed.(3)The study developed an experimental study on the bias performance of seven cruciform PEC stubs.The influence of each parameter on the failure mode,ultimate bearing capacity,and ductility performance of the eccentric short column was clarified,and the changing laws of the load-vertical displacement(N-Δ)curve and the load-strain(N-ε)curve were revealed(4)The finite element analysis model of the cross-shaped PEC biased short column was established,and the experimental data was used to verify the feasibility of the model.The detailed parameter analysis and the whole-process force mechanism analysis were carried out,and the validated finite element analysis model was used to evaluate the mechanical properties of the cross-shaped PEC short column under bias pressure.The results revealed the development and change laws of the contact stress and axial stress inside the short column at each stage.(5)This paper offered a calculation method of the axial and eccentric bearing capacity of the cross-shaped PEC short column by conducting design method of the cross-shaped PEC short column,and the accuracy of the calculation method is verified.The results were based on the test and numerical analysis in this paper,and combined with the existing research results at home and abroad. |
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