STUDY ON HOT SPOT STRESS CONCENTRATION FACTOR OF WELDED CONCRETE-FILLED STEEL TUBULAR TRUSS JOINTS

There are two main connection types for concrete-filled steel tubular truss structure, tubular intersecting welded joints and tube-gusset welded joints. With the use of ANSYS finite element software, the models of the K-type tubular intersecting joint, the tube-gusset joint and the broom type joint were established to study the stress concentration. The hot spot stress was calculated based on the method proposed by International Institute of Welding (IIW) and Det Norske Veritas (DNV). The hot Spot Stress concentration factors at the welding toes of the three welded joints under the typical loads were discussed. The results show that the tubular intersecting joints are small in shear stress range, and large in normal stress concentration factor. The stress concentration of tube-gusset joints is lower compared with the tubular intersecting joints. The maximum hot spot stress exists at the end of the tube-gusset joints. For the broom joints, the stress concentration is close to that of the tube-gusset joints, but the structure is relatively complex. According to the fatigue evaluation method based on the hot spot S-N curves, the concrete-filled steel tubular truss structure has good anti-fatigue performance when using the tube-gusset joints.