Restraint mechanism and bearing capacity calculation of steel-
concrete composite square columns with internal spiral bars |
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| Authors: | ZHOU Ji CHEN Zongping ZHOU Chunheng JING Chenggui |
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| Affiliation: | 1. College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China; 2. College of Architecture
and Civil Engineering, Nanning University, Nanning 530200, China; 3. School of Civil and Environmental Engineering,
Ningbo University, Ningbo 315211, China; 4. College of Civil Engineering and Architecture, Guangxi University
of Science and Technology, Liuzhou 545006, China; |
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| Abstract: | In order to reveal the restraint mechanism of steel-concrete composite columns with spiral bars, and clarify the influence of design parameters such as the spacing of spiral bars, the diameter of spiral bars and the ratio of diameter to width of spiral bars on the restraint strengthening effect of composite columns, 30 specimens of steel-concrete composite square columns confined with spiral bars, including 15 angle steel specimens and 15 steel tube specimens, were tested under axial compression. The failure process of specimens was observed, the mechanism of constraint strengthening was revealed, the influence of various parameters on axial compression behavior of the specimens was analyzed, and the unified formulas for calculating the axial compression bearing capacity of composite columns were proposed. The test results show that the built-in spiral bars can effectively improve the restraint arch effect of square angle steel skeleton or steel tube on the core concrete, and improve the bearing capacity and deformation performance of composite columns, but has no obvious effect on stiffness. The ductility of composite columns can be further improved by increasing the volume reinforcement ratio of spiral bars, and the bearing capacity of composite columns can be improved most significantly by increasing the diameter width ratio of spiral bars, followed by reducing the spacing of spiral bars and increasing the diameter of spiral bars. The improvement degree of the bearing capacity slows down with the increase of the amounts of spiral bars, and the improvement effect of the built-in spiral bars on the bearing capacity of angle steel reinforced concrete columns is significantly better than that of concrete-filled steel tube columns. Combined with the constraint model and Mander’s theory of confined concrete, the formulas established in this paper can accurately calculate the axial bearing capacity of steel-concrete composite square columns confined with spiral bars. |
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