Experimental study of ultra-large capacity end-plate joints

When bolted joints are required in steel structures involving large spans or heavy loads, ultra-large capacity end-plate joints with 12 bolts or 16 bolts in tension should be applied if ordinary end-plate joints or large capacity end-plate joints cannot meet the resistance requirement. Four full-scale specimens of ultra-large capacity end-plate joints were tested subjected to monotonic load. The moment-rotation curves of all the specimens were obtained, and the moment resistance, rotational stiffness, and distribution of the bolt strain increments in tension were analyzed when the bolt diameter, the end-plate thickness, or the layout of the bolts changed. The tested ultra-large capacity end-plate joints shared the failure mode of end-plate yielding followed by bolt fracture or necking, and the thickness of the end plate had an obvious influence on the joint resistance. A significantly inhomogeneous distribution of bolt strain increments was observed. Bolts in corners, which made little contribution to the moment resistance in the tests, could be removed or considered as shear-resistant bolts. In the design of this kind of joint, the resistance of the panel zone can be decided according to the Chinese code, the American code, or the Eurocode, and the equivalent number of the bolts in tension is recommended to be 7.0 based on a proposed distribution model of the tension load resisted by bolts in tension, derived from the tests.