Study On The Mechanical Performance Of Tappered Concrete-filled Double Skin Steel Tube Torsional Artifacts

The tapered concrete-filled double skin steel tubular columns have been widely used in building structures.In the practical engineering application,the conical section concrete-filled double skin steel tubular columns with large hollow rate is often used instead of the equivalent section concrete-filled double skin steel tubular columns.So that the structure more in line with the force requirements,and reduce the weight.Therefore,it is necessary to study the torsional composite mechanical properties of tapered concrete-filled double steel tube.This paper studies and analyzes the mechanical properties of tapered concrete-filled double steel tube pure torsion members,pressure torsion members,and compression torsion members.(1)The analysis model of concrete filled steel tube composite pure torsion,pressure torsion and bending torsion components with conical hollow interlayer is established.The rationality of the model in this paper is verified by the relevant experimental results of previous studies.Under the load of pure torsion,pressure torsion and bending torque,the whole torque-angle curve of typical components is analyzed.The interaction,failure modes and working mechanism among the components of the conical hollow sandwich composite members are analyzed.It is concluded that this kind of tapered concrete-filled double steel tube has better bearing capacity and plastic performance.(2)The main factors affecting the torsional bearing capacity of tapered concretefilled double skin steel tubular columns under different loads of pure torsion,pressure torsion,bending and torsion are analyzed.The influence of taper,hollow ratio,axial compression ratio,yield strength of outer steel tube,yield strength of inner steel tube and strength of concrete on torsional capacity of tapered concrete-filled double steel tube was analyzed.It is concluded that the significant parameters affecting the torsional capacity of the composite members are the taper and the yield strength of the steel tube.The torsional bearing capacity of three different composite members is compared and analyzed,which indicates that the torsional resistance of the tapered concrete-filled double skin steel tubular columns is relatively good.(3)According to the calculation formula in technical regulations for concrete filled steel tubular structures with hollow interlayers,the pure torsion component and pressure torsion component of the conical hollow interlayers are checked.The comparison between the finite element calculation results and the formula calculation results is safe.The calculation method of torsional bearing capacity of tapered concretefilled double skin steel tubular columns with large hollow ratio is proposed.Comparing the calculation results of the model,the agreement is good.