Study On The Effect Of Constitutive Model Parameters On The Precision Of Finite Element Analysis Method For Concrete Filled Steel Tubular Structures

Finite element software ABAQUS is used in this thesis,Aiming at the remaining problems of using ABAQUS in the analysis of concrete filled steel tubular structures,the following research works has been carried out:(1)The axial compression tests of concrete filled steel tubular short columns in previous thesis have been simulated and analyzed.different constitutive curves of concrete,consideration of concrete damage in monotonic analysis,different parameters of yield function of concrete and flow law have been compared.Based on the comparison of force-displacement curves and failure modes of members,the concrete constitutive parameters suitable for the analysis of concrete filled steel tubular stub columns under axial compression are selected.(2)The test of concrete filled steel tubular slender columns under cyclic loading in previous thesis is simulated and analyzed.The effects of different cyclic strengthening criteria of steel and different stiffness recovery factors of concrete on the simulation results are studied.The most suitable setting value of damage recovery factor is selected according to the minimum inaccuracy of capacity.(3)The interface between steel tube and concrete is treated in different ways,which are surface-to-surface contact and perfect bonding,respectively.The inaccuracy between the perfect bonding model and the test results is analyzed;(4)Two joints(one exterior joint,one inner joint)and a single-story single-span frame are simulated and analyzed with the model and parameters corrected by the previous works.A three-story two-span frame is simulated and analyzed too,and the inaccuracy between FEA model and test results is compared.Through above works,the following conclusions and suggestions can be drawn:(1)It is difficult to obtain the correct force-displacement curve by using plain concrete stress-strain curve in the axial compression simulation of concrete filled steel tubular short columns,and the confined concrete constitutive model can nearly predict the axial compression bearing capacity and deformation performance of concrete filled steel tubular short columns,but the relevant parameters of concrete need to be corrected.(2)In the simulation of concrete filled steel tubular slender columns under cyclic loading,the compress stiffness recovery factor of concrete has a significant effect on the shape of the horizontal force-horizontal displacement hysteresis curve.For the four examples selected in this paper,the finite element calculation results are in good agreement with the experimental data when the factor is set to be 0.6.(3)When the slip between steel tube and concrete is ignored,the peak capacity calculated by finite element method is larger,and the peaking displacement is smaller.(4)The finite element model established in this paper fits well with the force-displacement curves of the concrete filled steel tubular column to H-shaped steel beam joints,so as the single-story frame and main failure model of these specimens is reflected in the FEA model.However,the simulation of the three-story two-span frame of the concrete filled steel tubular column to H-shaped steel beam still has large inaccuracy.The main cause of the inaccuracy is FEA model do not take defects like rupture of welding line into consideration.