Finite Element Analysis On Hysteretic Behavior Of Chs-to-rhs Welded Y- And X-connections

The hollow steel section (HSS), with its beautiful appearance and reasonable mechanical behavior, has been widely used in convention centers, airport terminals, train stations and other large buildings. In rectent years, earthquake which happended frequently, caused huge losses of lives and property to the countries of the world. In response to this disaster, the scholars proposed the performance-based seismic design theory, which has been generally recognized by the scholars of the world and becomes the development direction of future structural design.This theory firstly requires the evaluation on the seismic performance of beams, colmns, connections, then the comprehensive evaluation on the seismic performance of the overall structure. However, as for the research of the HSS connections, the researchers at home and abroad mainly focused on the static performance and paid little attention to the hysteretic performance of the connections under cyclic loading. Especially, the research on the hysteretic performance of the CHS-to-RHS connections has not been carried out yet.Therefore, the numerical simulation analysis on the hysteretic performance of CHS-to-RHS Y-connections and CHS-to-RHS X-connections were conducted and displayed in this paper, using the ANSYS software. The concerned reasearch strategy is the combination of the typical model study and the large-scale parametric study. In the typical model study, some factors which impact the finite element analysis (FE) were determined, such as welding, boundary conditions and so on. In the parametric study, this paper studied the hysteretic behavior of these connections, in the case of changes of geometry parameters, material parameters or the pre-axial force of the chord. Besides, this paper made a comprehensive evaluation on the seismic performance of the two types of connections, on the basis of the results of the hysteretic curves, skeleton curves, hysteresis-loop area and energy dissipation factor.The hysteretic behavior of CHS-to-RHS Y-connections was compared with that of CHS-to-RHS T-connections, CHS-to-RHS X-connections and RHS-to-RHS Y-connections respectively,and the corresponding comparative evaluation on hysteretic behavior of the connections mentioned above was obtained here. What is more, this paper made a comparison of the finite element results and the quasi-static experiment results of two full-scale test specimens, proving the feasibility of using finite element analysis (FE) to study the hysteretic behavior of HSS connections. In addition, a functional relationship between the load-carrying capacities of the CHS-to-RHS Y-connections and the RHS-to-RHS Y-connections whose load-carrying capacity ratio were linear fitted was confirmed, on the basis of a large number of finite element results. The work may provide some useful information for the design of this type of connections.