Axial tensile behavior and strength of welds for CHS branches to SHS chord joints

• Eight X-joints with CHS branches to a SHS chord were tested to determine the axial tensile behavior of the welds.
• Uneven strain distribution in the non-rigid joints was in contrast to the uniform strain distribution in the rigid joints.
• The strength of the welds in non-rigid joints is significantly less than that of rigid joints.
• A prediction formula for the axial tensile strength of the welds is proposed.

In this work, experimental investigations were conducted on the axial tensile behavior of welds connecting tubular X-joints with CHS branches to a SHS chord. Five non-rigid and three rigid welded joints were tested under monotonic loading conditions. The weld properties were specially measured using a negative mold. Next, the strain distribution, the failure modes and the strength of the welds were obtained. The results indicate that an uneven strain distribution exists in the non-rigid joints in contrast to the uniform strain distribution in the rigid joints. The strength of welds for the non-rigid joints exhibits a significant reduction compared with rigid joints. Finally a predictive formula for the axial tensile strength of the welds is proposed according to the method of effective length based on experimental research and finite element analysis, which is capable of meeting the reliability requirements of the AISC specification.