Study On Stress Concentration Of Stainless Steel Uniplanar Hybrid Tubular Joints

The stainless steel structures have been used more and more widely in the building structure due to its attractive appearance,high corrosion resistance,good impact toughness,easy maintenance and high comprehensive cost-effective.At present,the fatigue performance study of the carbon steel tubular joints with pure circular or square hollow section chord and brace has been quite mature,and a lot of design specifications for the carbon steel material and structure have been published.While for the stainless steel tubular joints,the research of the fatigue performance is very little,especially for the joints with square hollow section chord and circular hollow section brace.The stress concentration factor is a fundamental index to evaluate the fatigue performance of the structure or component.Therefore,the paper analyzed the stress concentration factor of the stainless steel uniplanar tubular joints with square hollow section chord and circular hollow section brace under the action of axial force using the test method and finite element numerical analysis.In this paper,the following research works were carried out:(1)The tensile tests for the stainless steel tubes with four kinds of section dimension were conducted to study the mechanical property of stainless steel,in order to provide the reliable material parameter to the finite element numerical analysis.(2)The test were conducted to research the hot spot stress concentration factors of the stainless steel uniplanar welded T-joints and X-joints with square hollow section chord and circular hollow section brace under the action of axial force.According to the symmetry,the half of the joint was chose to be the studying object.The strain gauges were pasted on the chord and brace respectively,and the angles between adjacent strain gauges were 45°.The hot spot stress concentration factors of the positions were studied where the strain gauges were.(3)The finite element models of the stainless steel uniplanar welded T-joints and X-joints with square hollow section chord and circular hollow section brace were created using the finite element software ANSYS,and the analysis results were compared with the test results to check the validity of the models.Meanwhile,the solid models without weld were created to illustrate the importance of the weld.(4)Based on the current calculation formulae for the stress concentration factor of the carbon steel tubular joints with pure circular or square hollow section chord and brace,the parametric equations for the stress concentration factor of the stainless steel uniplanar welded T-joints and X-joints with square hollow section chord and circular hollow section brace were proposed on the basis of large number of parameter analysis.And the calculation results were compared with the finite element results to verify the high accuracy of the proposed parametic equations.