Finite Element Analysis Of Seismic Performance Of Regional Confined Concrete Columns

With the rapid development of high-rise and super high-rise buildings,it is difficult for traditional reinforced concrete columns to meet the requirements of ductility and bearing capacity at the same time.Previous studies have shown that regional confined concrete columns can effectively solve the problem of short columns under high axial pressure.Most of regional confined concrete(RCC)have involved rectangular column so far and the research on circular column is just beginning.ABAQUS finite element analysis software is used to simulate and analyze the seismic behavior with different axial compression ratios,shear span ratio,stirrup spacing and stirrup arrangement in this project.The main research work is as follows:(1)A comprehensive study on the theory of RCC column was carried out.The constitutive model of RCC is introduced.By comparing and analyzing the difference between the traditional confined concrete column and the RCC column in the distribution of confined stress,the restraint efficiency and the development of cracks,it is found that the RCC column can show good mechanical properties under many kinds of mechanical conditions.Meanwhile,the formulas for calculating the bearing capacity of RCC columns under axial and eccentric compression are derived and the joint force of concrete under compression on both sides and the position of the resultant force are obtained.(2)Based on the experimental data of RCC columns with axial compression ratios of 0.9and 1.1 under cyclic loading,the correctness of the ABAQUS finite element simulation was verified.The results show that the mechanical behavior of regional confined concrete columns under cyclic loading can be described more accurately when using concrete damage Model(CDP Model)to define concrete material and using the regional confined concrete constitutive model and the classical bilinear follow-up reinforcement model.The experimental results are in good agreement with the simulation results and the maximum error of horizontal bearing capacity is only 6.4%.Failure to consider geometric nonlinearity in modeling will overestimate the bearing capacity and seismic behavior of columns.(3)Quasi-static experiment of RCC column and core column was conducted under cyclic loading by using ABAQUS finite element software.Seven RCC column appeared axial compression ratios of 0.9/1.1/1.3,shear span ratio of 3/4/5 and stirrup spacing of50mm/75mm/100 mm while one core column present axial compression ratio of 1.1,shear span ratio of 5 and stirrup spacing of 100 mm.The hysteresis curves,skeleton curves,energy dissipation,stiffness degradation and horizontal bearing capacity of each specimen wasanalyzed.The results indicated that all specimens exhibited good seismic performance.With large axial compression,the horizontal bearing capacity of RCC columns was high,but the speed of decline of bearing capacity and the rate of stiffness degradation appeared relatively fast at the later loading stage with the relatively poor ductility and energy dissipation capacity.With large shear span,RCC column performed small horizontal bearing capacity,strong ductility and energy dissipation capacity.With large spacing of stirrups,RCC column with small constraint coefficient showed low horizontal bearing capacity,poor ductility deformation and energy dissipation capacity.With the same situation,the seismic behavior of RCC columns and core columns was basically the same.When the axial compression ratio was 1.1,the shear span ratio was 4 and the stirrup spacing was 50 mm,RCC column performed the best seismic behavior.It is proved that RCC column has good mechanical and seismic properties,while the research conclusion can provide reasonable reference for engineering design.