Enhancing braced frames’ lateral ductility by new beam-end splices of supported blade or sliding teeth: FE analysis

Abstract

For overcoming premature damages happened to steel beam-column-brace joints under significant story-drifts, researchers proposed different hinge-splices. In this paper, at first, the bolted beam-hinges of web double-angle splice (WLS), top-flange double-plate splice (TFS), and TFS with web shear-plate (TFS-W) are evaluated through validated finite-element models, in diagonal buckling-restrained braced frames. As a result, WLS inevitably possessed appreciable bending-rigidity, and its bottom bolts failed under one cycle of 2%-drift. Moreover, TFS suffered gradual beam-subsidences leading to drastic splice-bucklings, and TFS-W sustained additional fixity and web-slot widenings, under low-to-high gravity-loads and double cycles at 1, 2, 3, and 4% drifts. Hence, TFS’s shear performance was improved by adding web end-plates standing on cantilever-plates welded across beam gap, which both precluded the beam subsidence and facilitated cyclic splice-rotations. Subsequently, innovative supported-blade splices (SBSs) and sliding-teeth splices (STSs) are developed with four versatile configurations, and analyzed under the aforementioned incremental lateral-loading protocol. In SBSs, single axial blade-plates, and clamping support-plates or bolted connector-plates were economically incorporated. Alternatively, STSs utilized double shear-plates with multiple cantilever teeth inserted into fit socket-holes created in single end-plates. In consequence, SBSs effortlessly transmitted large gravity-loads and considerable beam-axial forces, while allowed maximal beam-column rotations with blade-plate bending smoothly along its slit/slotted mid-length. Furthermore, during the transfer of substantial shear-forces from brace to column or beam, STSs rotated steadily around their welded/bolted collector-plates by sliding their long teeth inwards/outwards the corresponding sockets, which merely caused superficial yieldings at tooth-socket interfaces.