The Experimental Research On Axial Compressiv E Performance Of Concrete-filled RPC Tube After Elevated Temperature

The concrete filled RPC tube named CFRT is a new type of composite structure developed by utilizing the ultra-high performance concrete and high-strength steel stirrup.It can exert the ultra-high compressive performance of RPC and the combination effects of confined concrete.The t ests on the mechanical behaviors of CFRT after exposure to high temperature are conducted in this paper.The main achievements can be summarized as follows:Research findings on thermal properties of concrete under high temperature are summarized.The finite element analytic modal was established with the universal finite element software ANSYS/14.5 to compute the section temperature field of CFRT stub columns.The coincidence between the calculated data and measured data proves the validity of finite element model.Experiment were carried out at high temperature on 15 specimens.The thermocouple was set inside the specimen.The change law of the temperature with time inside concrete was obtained under different temperature.The results showed that the closer to the center position of the cross section,the lower the temperature growth rate,the longer the temperature growth time.A little temperature crack along circular on the surface at the middle of the specimen after the specimen was cooled to normal temperature.All the formation of specimens were complete under high temperature,and no burst appeared.The results showed that the resistance of high temperature of CFRT was good.Totally 15 stub column specimens are conducted axial compression test after exposure to elevated temperature to explore the influence of different grade temperature,different stirrup spacing stirrup configuration and the strength of concrete on the failure mode and axial compression performance.Based on the ultimate capacity calculation method of confined concrete,this method mainly consider the effect of material strength damage under high temperature,using Mander(1988)confined concrete strength model to calculate the internal concrete strength.The capacity of prefabricated RPC tube and internal concrete is simply added.The results show that the formation of this method is simple and has a clear mechanical meaning.The ultimate capacity of CFRT can be better predicted after high temperature.