Research On Shear Behavior Of Square Concrete Filled Double-skin Steel Tubular Columns

With concrete filled double-skin steel tubular are widely used in practical engineering as long span bridge,heavy loading structures and high-rise buildings,it is necessary to research the mechanical properties of CFDST members.At present,scholars at home and abroad have studied the mechanical behavior of CFDST under axial compression,compression with bending and pure bending.There are few studies on the shear behavior of CFDST.This paper research the shear behavior of CFDST and suggest a formula to calculate shear capacity based on the results from numerical simulations.The research work is summarized as follows:1.The research results in experiment and theory related to this paper was reviewed and summarized firstly.Then identify the theoretical methods and simulation methods to studies the shear mechanical properties of square CFDST: use Finite element software ABAQUS to calculate and analysis the load-displacement curves of square CFDST under pure shear.2.Experiment of 16 concrete filled steel tubular under pure shear and 4 square CFDST members under compression bending and shear are simulated by finite element analysis methods.The correctness of finite element analysis methods is verified by comparing experimental results and simulation results.3.Based on the reliability of finite element analysis methods was verified well,this paper studied the load-displacement curves of different shear span ratio square CFDST under pure shear.The range of the shear span ratio corresponding to the shear failure of the members was determined.From the aspects of failure pattern,load-displacement curves and individual loading capacity of each part in square CFDST,indicated the working mechanism of square CFDST under pure shear.4.The effects of yield strength of inner and outer steel,concrete cubic compressive strength,nominal steel ratio on section,hollow ratio and diameter-thickness ratio of inner steel on shear capacity of square CFDST members were investigated.Then the effect factors were studied in the parametric analysis.Based on the results from multi-parameter analysis,a practical calculation formula for the shear capacity of square CFDST under pure shear was proposed by regression analysis.The reliability of calculation formula for the shear capacity of square CFDST were analysed.The calculation formula results are in good agreement with simulation calculation results,indicated that the simplify calculation formula can be used as a reference for relevant engineering structures.