Experimental and Numerical Analysis of the Performance of Circular Hollow Section KK′X Joints

Abstract:

The behavior of multiplanar KK′X gap joints in circular hollow section （CHS） trusses was investigated experimentally and numerically. First， failure tests on two KK′X joints with different geometric parameters were conducted with different geometric parameters to examine their deformation feature， failure mode， load-deformation responses， ultimate bearing capacities， and strain intensity distributions. Next， a finite element （FE） model of KK′X joints was established and validated against the experimental results. The plastic zone and its development were analyzed using this model. The results indicate that the failure mode of the all joints belongs to chord plasticization. The depression deformation of chord wall at K compressive brace came to maximum. Increasing the brace diameter could enhance the ultimate bearing capacity of the joint. The stress distribution near the intersection between brace and chord is more complicated， with the maximum strain intensity occurring at the chord saddle adjacent to the K compressive brace， where yielding initiates first. The plastic zone then propagates outward， eventually encompassing the most region of the joint region.