Secant Stiffness Method Research Based On 2D Non-linear Finite Element Of Reinforced Concrete

The material nonlinear properties of reinforced concrete have a great influence on the behavior of the structures. During the process of external force acting on the structures, the mechanic properties of the concrete and reinforcement change significantly due to the influence of the history loading. How to model the crack of concrete and the loading and reloading of the reinforcement and concrete under cyclic loading has been the focus of the researchers worldwide. From the work of Collins and Vecchio, we have a further understanding about the reinforcement and concrete nonlinear properties. Based on MCFT(Modified Compression Field Theory), proposed by Vecchio, Lai wuqing worked out NAP program and initially realized the analysis of 2-D components under monotonic and hysteretic loading considering the combined action of N, M and V. pointing at the problems existing in the NAP program, large amount work has been done which will be the basis of further study.In the paper the main work has been done as following:①The advantages and disadvantages between All-Secant stiffness and tangent stiffness in the nonlinear monotonic analysis were reviewed.②The principle and method in utilizing the elastic secant stiffness in the reinforced concrete nonlinear hysteretic analysis were presented.③Iterative method used by Lai Wuqing was revised by employing the so called secant stiffness method.④Improvement on concrete hysteretic constitutive model was carried out.⑤Replacement of the energy convergence criteria utilized by Lai Wuqing with that based on the secant stiffness was given.⑥Work out the new analysis program (NAP) based on the new nonlinear principle.⑦Case studies on large amount of monotonic and reversed cyclic analysis with the modified program on walls and panels were presented.⑧Comparison the analytical result with that from lai's program and experiments was undertaken.Such conclusions have been obtained as a result:①Better convergence and numerical stability are achieved in the analysis of 2-D reinforced concrete components using the new elastic secant stiffness than tangent stiffness.②Compared with"the quadrant method"proposed by Zhu Bolong, the complete...