Fracture Analysis Of T Style Steel Truss Joints Based On Ellipsoidal Strength Model

Currently, T steel truss is the one widely used heteromorphosis steel truss structure form, because of its unique style. And increasingly be used in many architectural structure, especially in large-scale structure such as stadium, exhibition center and ect. With the publication of Light Steel Truss roof Trapezium (Part of T Steel), T steel truss will be more widely applied in practical projects. And in-depth analysis of plane and space for the system of T style steel truss joints'capacity is needed.Chord and web member intersect on T steel truss joint, and the joint transfers and balances internal stress of the truss structures. So the T steel truss joints are of vital importance to overall safety. Geometric mutations, stress concentration, welding defects and welding residual stress envoys in joints area, then make the point district stress more complicated, and induce joints'fracture.Using the secondary development function of FE Code ANSYS and compiling ellipsoidal hydrostatic yield model as the subroutines program. Eighteen fillet welds were simulated numerically based on the ellipsoidal strength model. By contrast with test results, the revised coefficient k of crack index CI was proposed for the suggested ellipsoidal fracture model considering welding defects and residual stress. Based on the revised crack index CI, fracture analysis was performed on general chord joints and midspan joints of T style steel truss, the ultimate bearing capacity of T style steel truss joints is obtained and the details of preventing brittle fracture are proposed.The results provide experience for further research on other forms of T steel truss joints'failure mechanism and design.