Mechanical Properties Analysis Of Column Foot In The Column With Double Steel Tube-confined Concrete Columns Under Vertical Loads

Steel tube-confined concrete has been used widely in industrial and civil budilingsnow in our country due to its advantage of outstanding bearing capacity, good plasticityand toughness,excellent construction performance and good economic returns, etc,especially in monolayer industrial factory’s columns.The first application in Hefei is aheavy steel factory project of Rong an Power, and double steel tube-confined concretecolumns were used as the main vertical power transmission system. Through refer to thecurrent study situation of the steel tube-confined concrete laced columns at home andabroad,only a small amount of experiments were down in our country, the contents ofthe experiments and the range of paramenters were very limite, and almost no relevantprovisions in foreign, so it’s particularly necessary to carry out both theoretical andexperimental research of the steel tube-confined concrete laced columns in order toreveal its working mechanism, proposing a reasonable method of calculating,and guidethe engineering practice.First,the paper expounded the basic features,current research status and applicationof steel tube-confined concrete in domestic and foreign.Second, the author introducednine kinds of codes in home and abroad about calculating the ultimate bearing capacityof steel tube-confined circular concrete short columns under axial compression.According to the calculation principle of each code, the author cited75test dates ofsteel tube-confined circular concrete short columns under axial compression from thepart scholars and calculated,then the theoretical calculated results were compared withexperimental results. The calculated results of code CECS28:29got more closer tothose obtained results by the test when the steel ratio in certain range.Again,the papertook the double steel tube-confined concrete columns of B-axis intersects with the12-axis which were used in heavy press assembly1#factory in Hefei MetalformingMachine Tool Co.,Ltd for studying object. Through the surface strain instrument whichwere arranged on the outer surface of steel tubes, monitoring the change of strain in thesteel tubes column foot timely under eight combination modes of drives，thus obtainedsteel tubes stress under the vertical loads.Then， calculating the stress of the coreconcrete according to the theory. The calculated results showed that the stress ratio ofthe core concrete and the steel tube is roughly from4.5to5.0. Finally, using the finiteelement software ANSYS to simulate the force of the core concrete and steel tubes inthe column foot of double steel tube-confined concrete columns under the eight corresponding combination modes. Then, compared simulation results with and theactually measured datas and theoretical calculated values. The comparison resultsshowed that the simulation results have a good agreement with those obtained by theactually measured. At the same time,it also showed that the selection of unit types isaccorded with the actual during numerical simulation, providing a reference for similarprojects in numerical simulation.At the end of the paper, the author put forward some suggestions about designand construction on double steel tube-confined concrete columns according to theresults of the research, providing valuable datas and related reference for theoreticalresearch and application of double steel tube-confined concrete columns.