Study On Mechanical Properties Of Square Rubber Concrete Filled Steel Tube Members Under Pure Bending

In order to vigorously promote the concept of green building,actively promote the application of rubber concrete filled steel tube components made of rubber powder crushed by waste tires to replace coarse and fine aggregates,this paper systematically studied the mechanical properties and bending working mechanism of square rubber concrete filled steel tube members from two aspects of experiment and finite element numerical simulation.By calculating the bending capacity of rubber concrete filled steel tube members using the existing domestic and foreign related codes,comparing with the test and simulation results to verify relevant technical personnel provide reference.The specific research results and conclusions are as follows:(1)Based on the parameters of the shear span ratio and rubber powder substitution rate,six square rubber concrete filled steel tube members were tested under pure bending,and the failure forms and load deformation curves of the specimens were examined.The results show that: rubber concrete filled steel tube and ordinary concrete filled steel tube have basically the same mechanical properties,and show good ductility when subjected to bending failure.The shear span ratio has no significant effect on the ultimate bending bearing capacity and initial bending rigidity of rubber concrete filled steel tube members,and has a little effect on the bending rigidity in the use phase.The substitution rate of rubber powder has a greater impact on the bending rigidity of the component.The initial bending stiffness of the test piece with a rubber powder replacement rate of 10% is increased by 19.03% compared to the initial bending stiffness of the ordinary concrete filled steel tube components,but when the rubber powder replacement rate is 20%,the initial bending stiffness is lower than that of the ordinary concrete filled steel tube components 18.11%.(2)The ABAQUS finite element software was used to refine the modeling of rubber concrete filled steel tube members,and the rationality of the finite element model was verified based on the test results.And the constraint mechanism of rubber concrete filled steel tube members in the bending process was analyzed.At the same time,the research parameters were expanded to analyze the influence of steel content,rubber concrete strength and steel yield strength of the bending bearing capacity and bending rigidity of members.The results show that the finite element method can simulate the mechanical performance of square rubber concrete filled steel tube members under the action of bending moment.Increasing the yield strength of steel,the steel content and the strength of rubber concrete can increase the bearing capacity of the component.The steel content has a significant effect on the bending bearing capacity of the component.When the steel content increased from 0.092 to 0.160,the bending capacity of the member increased by 45.96%.(3)Introduced Japanese regulation AIJ(2008),British regulation BS5400(2005),European regulation EC4(2005),Chinese regulation GJB4142-2000,DB21/T1746-2009 and GB50936-2014.The calculation provide method of concrete filled steel tube bending capacity.The above rules are used to calculate and compare the bending capacity of rubber concrete filled steel tube members,and the results show that the above six specifications can be used to calculate the bending capacity of rubber concrete filled steel tube members,and the calculation results are conservative.Among them,the calculation result of Europeanregulation EC4(2005)is the most consistent.The bending bearing capacity calculated by the European regulation EC4(2005)is 9.55% lower than the test and finite element simulation results.In summary,pure bending mechanical tests and corresponding theoretical studies of square rubber concrete filled steel tube members were studied in the paper.Besides,this paper clarified the influence of various parameters on the bending capacity and bending stiffness of rubber concrete filled steel tube members,and revealed the difference in the calculation of bending bearing capacity of each regulation.It can provide a reference for the simplified formula of bending bearing capacity of rubber concrete filled steel tube members.