Flexural behavior of cold-formed thin-walled steel quadruple-limb build-up beam-column connections

Based on the combination of beam and column sections, a new type of beam-column connections wasproposed in order to realize the rapid assembly of the beam-column with its combination section. In order to study its flexural performance, monotonic loading tests were carried out on four groups of connections, and the failure modes and bending moment-rotation relationship of the connections were obtained through the tests. The influences of column thickness, the number of screws in the connection domain and the thickness of the end plate of the connection on the flexural performance of the connection were analyzed. This provided data for establishing an effective performance analysis model library of cold-formed thin-walled steel connections, and theoretically calculated the bearing capacity of the connection. The results show that the failure modes of this kind of connections mainly include screw pulling out or shearing, and bending failure of end plates. When the thickness of the column is doubled, the initial stiffness of the connection increases by 26% and the ultimate bending moment increases by 39.3%. When the number of screws in the connection domain is increased from three rows (6) to four rows (8), the initial stiffness of the connection only increases by 9.9%, and the ultimate bending moment only increases by 6.4%. When the thickness of the end plate increases from 4 mm to 8 mm, the initial stiffness of the connection increases by 45.5%, and the ultimate bearing capacity has no obvious change. It shows that the thickness of the column plate and the end plate of the connection have great influence on the initial stiffness of the connection, and the thickness of the column plate also has certain influence on the ultimate bearing capacity of the connection, while the number of screws has little influence on the initial stiffness and ultimate bearing capacity of the connection. When the thickness of the column is doubled at the same time, increasing the number of screws in the connection domain can improve the initial stiffness and ultimate bearing capacity of the connection. The bending moment-angle curves of four groups of connections show obvious nonlinear characteristics, and this kind of connections is determined to be semi-rigid based on Eurocode3 specification for steel structures in Europe. The ultimate bending moment of the connection is calculated through the stress analysis of the connection. By comparing the calculated value with the experimental value, it is found that the theoretical calculated value is in good agreement with the experimental value. The tested connections can also be used for box-type cold-formed light steel beam-column connections, which is conducive to rapid assembly. © 2023, Central South University Press. All rights reserved.