Experimental Analyses of Mechanical Performance of CFST Column to Assembled Steel H-Beam Connections
The mechanical performance of a new proposed type of cross-shaped connection with concrete-filled steel tubular (CFST) column and assembled steel H-beam was investigated. Cyclic loading tests on the cross-shaped connections are carried out by using MTS servo loading system. Comparative analyses are conducted based on the experimental results including hysteretic curves, skeleton curves and stiffness degradation curves as well as ductility coefficients of cyclic loading tests. Furthermore, effects of geometric parameters of ring-stiffened plate, axial compression ratio and backing plate on the deformation performance of cross-shaped connections are analyzed. The results show that the increase of width of ring plate and the shape change of ring plate from square to circle can both significantly improve the ductility and the hysteretic characteristics of connection. It is emphasized that the specimen with square ring plates is of better deformation performance but lower bearing capacity than the ones with circular ring plates. Besides, the backing plates always have positive effects on the hysteretic characteristics, ductility and energy dissipation of the CFST column connections. Conversely, the increase of axial compression ratio contributes negatively to both the bearing capacity and deformation performance of the connection specimens. It can be concluded that the presented cross-shaped connection is of good deformation performance relating to hysteretic characteristics, energy dissipation and ductility, which can provide reference towards engineering practice with potential perspective application.
Brace-Beam-Column Connections for Concentrically Braced Frames with Concrete Filled Tube Columns
Composite concrete filled tube~CFT! columns are advantageous for use in seismic resistant braced frame construction since these CFT columns are relatively inexpensive, stiff and strong. However, to utilize the composite behavior of the columns, the vertical component of brace force must be transferred through the beam-brace-column connection and distributed to both the concrete and steel in the column. Beam-brace-column connection details are critical for development of this composite action. This paper describes ana- lytical and experimental studies carried out to better understand the transfer and distribution of force to the joint. A range of beam-brace- column gusset plate connections were considered. It is shown that the majority of force transferred from the steel into the concrete occurs by bearing rather than by friction. Steel gusset plates with horizontal ribs, or gusset plates with holes, allow more force transfer and have more composite action than plain gusset plates. Slip deformations between the steel and concrete are likely to be too small to mobilize the strength of shear studs in these connections.
Strength and rotational stiffness of simple connections to tubular columns using flowdrill connectors
Abstract A new thermal drilling technique (the flowdrill process) has made it possible to use ordinary bolts in tapped holes in relatively thin-walled tubes. This in turn has opened the opportunity for traditional partial depth and flush endplate connections to be used to join open section beams to tubular columns in simply designed braced steel frames. The experimental work reported concerns a series of tests conducted to investigate the moment capacity and rotational stiffness of simple joints bolted to tubular columns using flowdrill connectors. Tests show the connections to behave in a manner suitable for use as either pinned or partial strength connections for simply designed braced steel frames. This paper is one of a series; the others deal with moment-resisting connections and the influence of filling the tubes with concrete.