Inelastic Dynamic Analysis Numerical Method Of Reinforced Concrete Frame Structures

The multi high-rise reinforced concrete frame structure has been widely used in urban construction because of its good characteristics such as flexible layout,light weight,less material and good integrity.There is no doubt that accurate inelastic dynamic analysis is particularly important.And the reinforcement in reinforced concrete structure plays a decisive role in the hysteretic behavior of the structure,while the accurate reinforcing bars model becomes one of the key factors that affect the reliability of the structural analysis results.A brief overview of the current research situation of steel constitutive model,a hysteretic stress-strain relationship of reinforcing bars is presented,named “reinforcing bars hysteresis model of reinforced concrete structures”.It is considered a part of the bond slip effect through reinforcing bars.In which the complete path-dependent cyclic constitutive model is obtained by combining two monotonic envelopes and two cyclic loops.The monotonic envelope comprises an elastic range and a linear hardening zone.The cyclic loop includes an unloading branch and a reloading branch.The unloading branch is a line.Based on the classical bond stress-slip hysteretic curve which has the “frictional branch” and the “reloading branch”,the reloading branch follows cubic curve which has lower stiffness than the Ramberg-Osgood one.And programming the UMAT of reinforcing bars in the ABAQUS common numerical analysis platform.The present model and the other existed models are used to predict the hysteretic behaviors of six RC structural test results.It is shown that predictions of the present model are in better agreement with the experimental results than ones of the other models.The results show that it is an effective numerical analysis method to describe the bond slip damage between concrete and steel bar by means of the constitutive relation of steel bars under the “weakening”of reloading stiffness and the “hysteretic energy dissipation coefficient”.The core region of the supercell is replaced by a planar four-node element,and a new beam-column node element based on the planar four-node element is established,named “dynamic super DOF(degree of freedom)beam-column element”,the bond slip effect of steeland and the core area concrete is considered,and the dynamic non-linear calculation is carried out by implicit Newmark algorithm.The subroutine of this element has been developed UEL program in the ABAQUS.The validity of this program is verified by a series of numerical simulations.It is of practical significance to the nonlinear analysis of reinforced concrete structure to practical application.