FINITE-ELEMENT MODELING OF TUBULAR JOINTS .1. NUMERICAL RESULTS

The results of a study of 12 tubular joint models with varying branch to chord diameter ratios beta and branch inclination angles theta, subjected to axial tension, axial compression, and in-plane bending moment, are presented. The analyses were performed using finite-element software that is capable of modeling elasto-plastic material behavior and geometric nonlinearities as well as ductile and brittle fracture. The results showed that the current use of sin(theta) in design equations for inclined branches is reasonable, but somewhat conservative. When compared with the current experimental database, a close correlation of results was obtained for all axial tension cases, and for axial compression and in-plane bending moment cases for low to moderate beta values. For a beta value of 1 and compression and bending loads, the enhanced strength that was observed was attributed to uncertainty in the definition of failure, and the effects of various support conditions and chord lengths in the experimental studies. It is recommended that these properties be standardized for the definition of the database.