Three-dimensional Macro-Modeling of Beam-to-rectangular Hollow Section Column Joints under Cyclic Loading. Part 2: Modeling of Beam-to-column Joint by Extended Component-Based Approach

A rectangular hollow section (RHS) is compact and has remarkable structural performance, and therefore, RHS tubes are regarded as efficient column members in building steel structures. While the omission of continuity plates (diaphragms) at beam-to-column joints substantially simplifies the fabrication of the beam-to-tubular column joints, it causes the joints to decrease in rigidity, and thus, to be semi-rigid owing to a local out-of-plane deformation of the column tube. Presently, there is a lack of suitable modeling for this type of beam-to-column joint that can describe the three-dimensional semi-rigid behavior of the joint. The purpose of the present study is to establish a three-dimensional macro-model of the beam-to-RHS column joints, especially under cyclic loading conditions. In Part 2 of this two-part paper, a cross-section component, which is a multi-degrees-of-freedom structural element, is introduced to describe the local deformation of the cross-section of the RHS column tube. A three-dimensional beam-to-RHS column joint model is then assembled with the cross-section components, which can describe the complex three-dimensional behavior of the beam-to-column joint. The modeling approach adopted in this study is regarded as an extension of the component method for the modeling of steel joints. The feasibility of the proposed macro-modeling of the beam-to-RHS column joint is verified by comparison with loading test results of previous experimental studies.