Static behavior of aluminum gusset joints with titanium bolts for reticulated shells

This study presents 10 full-scale static tests on 6082-T6 aluminum alloy gusset joints assembled with TC4 titanium alloy bolts under pure bending, tension bending, and compression bending, with axial forces ranging from −100 kN to 100 kN. The joints exhibited a four stage M -Φ response consisting of the fixed stage, slipping stage, bolt hole bearing stage, and failure stage. Under pure bending and compression bending, failure was governed by flexural torsional buckling of the member flange, whereas under tension bending the governing mode shifted to net section fracture. Increasing axial tension further changed the fracture path from an almost transverse crack at +50 kN to an inclined tearing path of about 45° at +100 kN. The slipping stage stiffness showed the largest scatter, with a maximum COV of 0.61 under −100 kN compression bending. A finite element model calibrated against the tests reproduced the global response envelope, resistance level, and governing failure location, while the stagewise rotational stiffness was characterized primarily from the tests. The results clarify how axial force governs the failure mode transition and provide experimental evidence for the mechanical assessment of low-magnetic aluminum alloy gusset joints.