Parametric Study on Strengthening Methods for Welded Hollow Spherical Joints

Welded hollow spherical joints(WHSJ) feature simple configuration, reliable force transmission and sound economic efficiency, making them one of the most commonly used joint types in long-span spatial steel structures in China. A number of early long-span spatial structures in the country have been in service for more than 50 years. These structures are plagued by issues including structural aging and joint damage and failure, hence there is an urgent need for reinforcement and remediation. This paper presents a comparative analysis of different reinforcement techniques for welded hollow spherical joints. Adopting finite element analysis and parametric analysis, the strengthening performance of four reinforcement schemes — trapezoidal plate reinforcement, triangular plate reinforcement, sleeve reinforcement and outer ring rib reinforcement — is systematically investigated. The results show that trapezoidal plate reinforcement performs well under tension, compression, bending and other loading conditions, with the bearing capacity improvement coefficient ranging from 1.25 to 1.60. Triangular plate reinforcement also boasts good practicality, with its bearing capacity improvement coefficient reaching approximately 1.15 to 1.50. The single ring rib reinforcement achieves the best strengthening effect under in-plane bending of the stiffening rib, where the bearing capacity improvement coefficient can exceed 1.50. In addition, the applicability of different reinforcement methods varies remarkably with the parameter changes of welded spherical joints. The research conclusions can provide theoretical reference and data support for the design, reinforcement and maintenance of welded hollow spherical joints.