Static Behaviour Of Overlapped KT-Type SHS Joints

Directly welded overlapped KT-type SHS (Square Hollow Section) joints, which are made up of three branchs and one chord, are very common in SHS trusses.there isn't any formula for the direct calculation of KT-type joints' strength, which hamper the application of this type of joint.Using ANSYS PROGRAM, the load-carrying capacity of the joint is studyed by numerical analysis.Here are the main parts of the analytic work:(1) The ANSYS model of the joint is constructed.Through the contrastive analysis, several conditions as boudary condition,loading condition used in FEA(finite element analysis) are fixed.The loading proportion of the branchs is got from the first KT-type joint in the lower chord of a Warren truss from the left side.After the comparison of the two deformation limits which are 0.03b0 and 0.06b0, 0.06b0 is chosen for the joints studyed in this paper.(2) The joints with changing parameters are calculated.According to the calculated results,the joints are divided into 4 types.One representative joint is chosen from each type and studyed to analyse the stress distribution,stress development and the load-displacement curve.Through the comparison of the load-displacement curves of different joints, the influences of main parameters on the static behaviour of the overlapped KT-type SHS joints are analysed with the chord compressed or not.(3) Through the multi-parameter regressive analysis, two formulas are presented.The first one is a strength formula for overlapped KT-type SHS joints with no chord axial load and the second one is used to calculate the factor caused by chord axial load.In fact, strength formula for overlapped KT-type SHS joints with different chord axial load can be deduced from multiplying the two formulas mentioned previously.