Experimental Research On Restoring Force Characteristic Of Steel Reinforced Concrete Special-Shaped Column Frame Joints

The special-shaped column structure can largely make up the shortcomings of traditional rectangular column structures, such as the avoidance of dead space on room layout; the space reduction brought by traditional column edges and the restriction of furniture arrangement. Additionally, the new structure can create more economic benefits for the estate development, while implemented the idea of economical use of land under the circumstance of increasingly shortage of residential building area. In recent years, although the special-shaped column structure attracts broad attention from academic cycles in many countries, it still has some insufficiencies, which are mainly known as the low bearing capacity, low ductility, poor seismic performance and the like. Based on this, for the purpose to make full use of the unique advantages of special-shaped column structure, while in concurrent, make up the mentioned defects and deficiencies, the steel reinforced concrete (SRC) special-shaped column structure was proposed. In this paper, the restoring force characteristics of SRC special-shaped column frame joints have been systematically analyzed. Relevant details in this research could be summarized as following:(1) The experimental study was carried out to test related performances of the chosen 17 specimens of SRC special-shaped column frame joints under low cyclic loading. In the mean time, the parameters of steel configuration forms, axial compression ratio and steel ratio were taken into account in the designing of these specimens. The loading measure was designed to exert external loading on the end of columns by taking load-displacement effects into consideration. (2) By paying attention to the failure process of above mentioned specimens, the failure patterns of them were analyzed. With respect to the experimental results, the hysteretic curve and skeleton curve were drawn out to get insight into the restoring force characteristics, which contains hysteretic characteristics, ductility, energy dissipation and stiffness degradation rules. The results show that the failure of the SRC special-shaped column frame joints can be described as a four-stage process from initial cracking, yield, ultimate to the final destruction. Comparing with the reinforced concrete special-shaped column frame joints, the hysteretic loops of the SRC special-shaped column frame joints are plumper, the descending curve is gentler and the displacement ductility coefficient together with the viscous damping coefficient are higher. These prove that the SRC special-shaped column frame joints have better restoring force characteristics and seismic performance.(3) With the acquired experimental data, the dimensionless skeleton curve model was fitted; the stiffness degradation rules were obtained as well. Upon such foundation, a three-line restoring force model which fits for the SRC special-shaped column frame joints is established.The researching results of this paper paved down solid foundation for the establishment of both the calculation theory and time-history seismic analyzing measures for SRC special-shaped column frame joints. Further, it would be reasonable to believe that the application of such an excellent structural system in the future might be more prosperous.