Research On Deformation Limits Of RC Column Based On Material Strain

RC columns are important lateral force resistance components in structures, of which thedeformation capacity and failure mode of damage have a great effect on the seimicperformance of structures. At present, the seismic deformance indices of RC column in theperformance based design method of Chinese codes are just controlled by force instead ofquantified by numbers, which lead to inaccurate evaluation of the degree of damage in theseismic design process. This paper studies mainly on the seimic performance and thedeformation indices of column in different performance state, which include the contentslisted as follows:1. Summarize the RC column seismic performance experimental researches done byinternal and abroad scholars, and gather a patch of experimental data of RC columns in thedatabase of UC Berckeley. Then using ABAQUS to simulate the specimens. Thedamage-plasticity model of concrete and the double oblique model of reinforcement areadopted. The simulated load-displacement curve and the failure modes are in good agreementwith the experimental results, which indicates that in conditions of reasonable materialconstitution and FEA parameters, simulation of the stress state and failure mode of RCcolumn is feasible.2. Discuss the classification of the failure modes of RC column. By collecting theexperimental data of111columns and analyzing the relationships between factors likeshear-span ratio, area stirrup ratio, stirrup spacing and the failure modes of RC column, bringup to use shear-span ratio and flexural shear ratio as control factors of the failure modes of RCcolumn, and provide detailed classification.3. With reference to foreign specifications, this paper considers the description on thedeformation performance state and degree of failure of RC column in Chinese codes, bringsup to adopt the strain value of concrete and reinforcement, together with the bearing capacityof components as conditions to classify the performance state of RC column. The componentswith flexural and flexural-shear failure can be classified into6performance states: intact,slightly broken, light medium broken, medium broken, severe broken, ultimate state; thecomponents with shear failure can be classified into two states: yielding and ultimate state.4. On the basis of verification of the rationality and reliability of FEA method, bychanging shear span ratio, stirrup ratio, reinforcement ratio, flexural shear ratio and axialcompression,380RC column specimens are designed to numerically simulated by ABAQUS.The effect of axial compression ratio, reinforcement ratio, stirrup ratio on the plasticdeformation ability of RC column are mainly analyzed. Then deformation limit values of RCcolumn in different failure state are given which have been exaimined to make sure they areconservative values and can provide references to performance based seismic design.