Monotonic bending behaviour of TOBs bolted beam to SHS column connection with stiffening component

Abstract

Three types of prefabricated stiffening components that can be used in Square Hollow Section (SHS) columns and a complete assembly process are proposed in this paper. A total of six full-scale Thread-fixed One-side Bolts (TOBs) bolted beam to SHS column joints with stiffening components were tested under monotonic quasi-static load. The stiffening component and endplate stiffener are variables for the six tested joints. The failure modes, bending moment curves, and strain responses of each joint are generated and analyzed in this paper. The results show that four failure modes appeared in the tests, namely endplate yielding with SHS wall deformation, beam yielding with SHS wall deformation, endplate and beam yielding with SHS wall deformation, and beam yielding. Importantly, a thread depth of 1.2 times the bolt diameter ensures that no thread failure occurs before the bolt fails. In terms of structural performance, welding vertical and transverse diaphragms in the stiffening components can improve joint initial rigidity by 9.8%–51.6% and yield bending moment by 14.2%–17.7%. Moreover, endplate stiffener and diaphragm inside the stiffening component can improve the deformation storage coefficient by 1.4%–40.0% and 27.9%–31.7%, but weaken the strength storage coefficient by 4.1%–10.9% and 6.8%–13.5%, respectively. By comparing the joints with that using spliced column, the assembly process for stiffening components proposed in this paper can result in a better structural response. Finally, the computational methods including endplate, SHS column, and beam analysis models are recommended to predict the yield bending moment of such joints. Validation results of the tested joints show that the predicted yield bending moments are in good agreement with the test ones, and the errors between them remain 0.6%–13.9%, with an average of 5.2%. • Assembly process of prefabricated stiffening components in SHS columns are proposed. • TOBs bolted beam to SHS column connections with stiffening components were tested. • A thread depth of 1.2 times the bolt diameter ensures that the TOB is not pulled out. • Assembly process proposed in this paper results in a better structural response. • Computational methods of this kind of connections are recommended.