Study On Axially Compressive Behavior Of Concrete-Filled Aluminum Tube After Exposure To High Temperature

Concrete-filled aluminum tubular columns have better corrosion resistance and low temperature resistance than concrete filled steel tubular columns,and have light weight and high material recycling efficiency.It is an environmentally friendly structural bearing component with great application prospects.However,due to the relatively low high temperature mechanical properties of aluminum alloy,the synergistic effect of aluminum alloy tube and concrete after high temperature and its influence mechanism on the compressive bearing capacity of concrete-filled aluminum tubular columns cannot copy the existing theory and methods of high temperature mechanical properties of concrete filled steel tubular columns.Therefore,it is of great significance to study the axial compressive behavior of concrete-filled aluminum tubular columns after exposure to high temperature.This paper has achieved the following main results.Standard tensile specimens were intercepted from 6063-T5 and 6061-T6aluminum alloy round and square tubes respectively.Tensile tests of aluminum alloy materials were carried out at room temperature(20℃),100℃,200℃,300℃,400℃and 500℃.The yield strength,tensile strength,equivalent yield strength ratio and stress-strain relationship curves of aluminum alloy materials after high temperature were obtained.Considering the influence factors such as section form,wall thickness and the highest temperature experienced by the specimens,the experimental study on axial compressive behavior of square(12)and round(12)concrete-filled aluminum tubular columns after exposure to high temperature was carried out.The failure modes,stress-strain curves and ultimate load-carrying capacity of the short columns under axial compression were obtained.The influence mechanism of section form and confining effect coefficient on the deterioration of mechanical properties of the short columns after exposure to high temperature was revealed.Based on the deterioration model of material mechanical properties of aluminum alloy and concrete after exposure to high temperature,the finite element model of concrete-filled aluminum tubular columns were established by using ABAQUS software.Considering the influence parameters such as yield strength of aluminum alloy,strength of core concrete,confining effect coefficient and aluminum content,.The deformation law,failure characteristics and load-bearing capacity of the axial compressive behavior of concrete-filled aluminum tubular columns after exposure to high temperature are simulated.The variation of axial compressive strength coefficient(K_Y)of concrete-filled aluminum tubular columns after exposure to high temperature was obtained.The synergistic action mechanism of aluminum tube and core concrete after exposure to high temperature was revealed by combining the factors of section form,confining effect coefficient(ξ)and temperature(T).Based on the conclusions of experimental research and finite element simulation,the feasibility of the existing classical calculation theory and method for the axial compressive capacity of concrete filled steel tubular column was compared and analyzed.The temperature(T)and the coefficient of confinement effect(ξ)as parameters was fitted to obtain the calculation coefficient(K_Y)of the axial compressive behavior of concrete-filled aluminum tubular columns after exposure to high temperature.A method for calculating the bearing capacity of the axial compressive behavior of concrete-filled aluminum tubular columns based on superposition theory was proposed.