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.
Comparative inelastic analysis of RCC and steel-concrete composite frame
The majority of building structures are designed and constructed in reinforced concrete which are mainly depends upon availability of the constituent materials and the level of skill required in construction, as well as the practicality of design codes. R.C.C is no longer economical because of their increased dead load, hazardous formwork. However composite construction is a new concept for construction industry. The use of modern composite systems, allowing the erection of multi-story structural frames to proceed at pace. The reviews shows that, the composite structures are best suited for high rise buildings compared to that of steel and reinforced concrete structures. Unfortunately, many of the available nonlinear analysis programs are only suitable for modeling traditional steel or reinforced concrete systems and are not directly applicable to composite frames. Part of this work presented herein is aimed to understand the nonlinear behavior of composite frame using ETAB 9.7.
Experimental Behavior of Connections to Concrete-filled Steel Tubes
Six large-scale connections were tested to failure using the quasi-static test method. All details consisted of a connection-stub which was shop fabricated and field bolted for construction. Experimental results indicated that welding the connection-stub directly to the skin of the steel tube resulted in a large deformation demand on the tube wall. Large tube wall distortions made the girder flange, the flange weld, and the tube wall highly susceptible to fracture. Inelastic cyclic behavior improved when external diaphragms were used to distribute the flange forces around the tube, and the connection was able to develop the bending strength of the girder. Using embedded elements to distribute the girder flange force to the concrete core was very efficient in alleviating the stress concentration on the tube wall, however, the connection performance was sensitive to the type of embedded elements. Deformed bars welded to the girder flange and embedded into the concrete core developed a connection strength of more than 1.5 times the plastic bending strength of the connected girder, and exhibited stable hysteretic behavior up to failure. Connections with continuous flange plates showed less promise without additional detailing to anchor the flange plate into the concrete core. Extending the girder connection-stub through the entire CFT column was sufficient to develop the full plastic bending strength of the connected girder, and exhibited favorable inelastic cyclic performance.