In a structural analysis for building frames, column-to-beam connections are assumed generally as a rigid and/or pinned condition for analysis simplicity. It gives some discrepancy for an overall behavior of building frames having some rotational rigidity of all connections. Many researchers have interested and studied on a structural behavior for building frames with semi-rigid connections. Despite many structural merits of Concrete Filled Steel Tubular (CFT) Columns, it may not be clear for exact structural behavior between CFT columns and steel beams. This paper is focused on a moment-rotation relationship for CFT frames composed of beam-column connections of exterior diaphragm with four rectangular plates. It has been known by some experimental results that CFT frames with the exterior diaphragm connections have represented as a semi-rigid condition with a low stiffness due to out-of-plane deformations of square tubes. The main purpose of this study is to get a function formula of the moment-rotation curve for the connections. There are not sufficient for test results of the connections to get a function. Therefore, an analytical approach needs to be utilized using a finite element program, ANSYS. The analysis models are made from existing test specimens and additional models are made for the implementation for insufficient test results. The function of moment-rotation curve is proposed using three-parameter power model and least-mean-square technique. The initial rotational stiffness of beam-to-column connection is determined by slope from zero to the analytical results.
展开▼
