Static Behavior Of Circular Tubed Reinforced Concrete Stub Columns Under Axial Compressive Loading Under Constant High Temperature

Steel tube confined concrete is a new kind of composite component,its main structure is the traditional concrete filled steel tube structure,the node will steel tube broken.The main mechanical characteristics of steel tube confined concrete steel tube is not directly under vertical load.Steel tube confined concrete compared with the traditional concrete filled steel tube with high bearing capacity,the bottom frame column in high-rise buildings,the equipment have become more widely used in the layer column.Steel tube confined concrete structure can decrease the size of cross section at the same time,thus increase the use of building area,the structure of steel tube confined concrete short column effect has been effectively avoided.So this article focus on steel tube confined concrete structure research,selection of cross section forms for circular steel tube confined concrete as a key research object.Steel tube confined concrete structure were analyzed under the condition of constant high temperature,mechanical performance under vertical static load.Specific content is as follows:First of all,the selection of ABAQUS as a finite element tool,this paper introduces the solving process of ABAQUS,the analysis steps,and simply expounds the constitutive relations of concrete filled steel tube and the establishment of the constitutive relation,by choosing reasonable unit types such as the establishment of a constant temperature of the steel tube confined concrete temperature field finite element model,and compared with previous experimental data and verify the accuracy and reliability of the model in this paper.Secondly,this paper introduces the damage model of concrete filled steel tube,steel tube confined concrete under constant temperature has carried on the stress analysis,through choosing reasonable unit types such as the establishment of a constant temperature of the steel tube confined concrete statics finite element model,and with previous experimental data of steel tube confined concrete(room temperature,the temperature of steel tube confined concrete and the steel tube confined concrete after high temperature)to compare and verify the accuracy and reliability of the model in this paper.Finally,the paper analyzes the constant high temperature condition under axial load carrying capacity of steel tube confined concrete main influence parameters with ambient temperature,the size of the steel tube confined concrete section,steel ratio,strength of concrete and steel tube strength.Through analysis the environment temperature has significant effects on the bearing capacity of steel tube confined concrete,when the environment temperature,the structure of the steel tube confined concrete elastic modulus is reduced,resulting in bearing capacity of steel tube confined concrete declines;Under normal temperature,when the increase of section size,the ultimate bearing capacity of the components significantly increased,temperature,ultimate bearing capacity increases slowly,when the temperature reached 800 ℃,almost without rising trend;When the increase of steel ratio of steel tube,component limit bearing capacity has no obvious increasing trend;Under normal temperature,when the increase of concrete strength,ultimate bearing capacity significantly elevated in the components,and the temperature rise,ultimate bearing capacity increases slowly,when the temperature reached 800 ℃,almost without rising trend;When steel tube strength increase,rising component of ultimate bearing capacity is not obvious.