Interface Bond Slip Of Concrete Filled Steel Tube Column With Built-in Ring Steel Plate

Because of its excellent mechanical properties,concrete-filled steel tube columns are increasingly used in various high-rise,long-span and heavy-load structures.At present,in order to enhance the joint working performance between steel tube and concrete,structural measures such as welding studs and stiffening ribs in the tube can be generally adopted to ensure the interfacial adhesion between steel tube and core concrete,but this structural measure has a large welding workload and complicated construction,which has caused certain construction difficulties.In recent years,as a structural measure to enhance the cooperation between steel tube and concrete,inner ring steel plate has attracted the attention of the engineering community.The inner ring steel plate can not only improve the restraint capacity of concrete filled steel tube,but also occupy less space inside the steel tube and will not conflict with the stressed steel bars in the tube,which is convenient for construction.Based on this,this paper puts forward a shear-resistant structure with inner steel plate instead of welded studs,and studies the bond shear-resistant performance of circular,square and octagonal cross-section concrete-filled steel tube columns with inner ring steel plate by ABAQUS finite element analysis software.The main research contents and conclusions of this paper are as follows:(1)The accuracy of the modeling method is verified through the existing tests,and the loading process,failure characteristics,bond shear capacity and load-slip curve trend of the tests and finite element simulations are compared.The results show that the failure characteristics of the finite element model are similar to the experimental phenomena,and the load-slip curve is in good agreement with the curve trend obtained from the tests,which proves that the modeling method adopted in this paper is feasible and accurate.(2)ABAQUS is used to build 90 concrete-filled steel tube columns with girdle plates.According to the calculation results,the stress of concrete-filled steel tube column with inner ring steel plate is analyzed,the concluded that the buckling deformation of concrete-filled steel tube columns with girdle plates can be effectively prevented.The maximum bond bearing capacity and load-slip curve of concrete-filled steel tube columns with embedded steel strips and embedded ring steel plates are compared and studied,which proves that ring steel plates are far stronger than steel strips in improving the interfacial bond performance of concretefilled steel tube columns.(3)The parameters of the simulation results are analyzed,and the influences of the thickness of steel tube,the thickness of ring steel plate,the number of layers and the spacing between layers on the bonding properties are studied respectively.With the increase of the thickness of steel tube,the thickness of ring steel plate and the number of layers of ring steel plate,the bond bearing capacity of concrete filled steel tube columns with three sections is obviously improved.When the conditions of three kinds of concrete-filled steel tube columns are the same,and the spacing of ring steel plates changes in the range of 0-200 mm,the bond bearing capacity increases with the increase of spacing.(4)The composition of bond shear capacity between steel tube and core interface is analyzed.According to the existing formulas,the calculation formulas of bond shear capacity of concrete-filled steel tube columns with circular section,square section and regular octagonal section are put forward respectively.