Behavior of RHS X-joints having high brace to chord width ratio under axial compression

摘要

In this study, the behavior of rectangular hollow section (RHS) X-joints having a brace to chord width ratio (BCWR) higher than 0.85, or the behavior as affected by the chord sidewall buckling was investigated experimentally and analytically. The experimental program tested six full-scale RHS X-joints fabricated from both ordinary and high strength steel under axial compression. All high strength steel specimens with a measured yield stress as high as 700 MPa exceeded the Eurocode design strength with sufficient margin. Significantly different joint behavior was observed depending upon BCWR; the joints with high BCWR exceeding 0.85 was very brittle with rapid post-peak strength degradation irrespective of steel grades. According to the test results, brittle behavior of RHS X-joints as affected by the chord sidewall buckling seemed probable at a BCWR less than 0.85. The sidewall buckling strength for RHS X-joints in Eurocode was again shown to be very conservative, and a new strength formula was proposed. The effect of chord stress was also numerically investigated based on test-validated FE nonlinear analysis.