Creep-Effected Dynamic Response of a Concrete-Filled Steel Tubular Member in Axial Compression and Impact Load
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CREEP-EFFECTED DYNAMIC RESPONSE OF A CONCRETE-FILLED STEEL TUBULAR MEMBER IN AXIAL COMPRESSION AND IMPACT LOAD H. Y. Qiao,a Y. M. Yao,a C. S. Li,a X. G. Jiang,b M. Ding,b c
Y. D. Wang, and T. Lan
UDC 539.4
d,1
The finite element model of a tubular member under the combined action of axial compression, creep, and axial impact was constructed with the numerical analysis software, to evaluate the core concrete creep effect on the dynamic responses of a steel tubular member in axial compression. In the model, the creep effect of core concrete of different age is equivalent to the change of its elastic modulus. Then, the dynamic responses of a tubular member in axial compression and impact were simulated considering the creep effect, time-history curves of impact load, contact time, axial deformation, stress and strain were plotted, and the effect of creep on them was discussed. The impact load peak decreases with the development of the core concrete creep, and the most is about 51%; the contact time and axial deformation increase; the concrete stress decreases, but the concrete strain increases greatly. The minimum and maximum principal concrete strains after 30 years exceeded those after 28 days by 6.35 and 8.6 times, respectively. The core concrete creep has a less effects on the stress and strain of the steel tube. The fruits provide a scientific help for the impact resistance design of a concrete-filled steel tubular member in axial compression. Keywords: concrete-filled steel tubular member, axial compression, numerical simulation, creep, dynamic response. Introduction. Concrete-filled steel tubular member has been widely used in industrial factory building, trestlework, metro platform, high-rise or super high-rise structure, and bridge structure, etc. due to advantages, such as high bearing capacity, good plasticity and tenacity, easiness of construction, lower price, good fire resistance, and the beautiful layout, etc. [1, 2]. Creep will occur in the core concrete when concrete-filled steel tubular member bears the axial compression load. Creep can produce the internal force redistribution along the concrete section and steel tube section, i.e., concrete stress becomes smaller and steel tube stress increases significantly. Sometimes, when concrete-filled steel tubular member bears a large dynamic load by chance, the steel tube would possibly enter the plastic state in advance and the local buckling would happen. Creep has a big impact on the natural vibration frequency and dynamic response of concrete-filled steel tubular member, especially in the early stage when creep happens [3]. Studies on mechanic performance of concrete-filled steel tubular member started in a large scale from the later 1960s, and mainly focuses on static performance and dynamic performance [4]. Began earlier than the dynamic performance study, the static performance study has progressed from experimental study to establishing the constitutive relation of concrete-filled steel tube, and achieved many valuable research results [2, 5–7].
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