Static Elasto-Plastic Analysis Based On Abaqus Fiber Beam Element

Fiber beam model is based on constitutive relations of material. Comparing with plastic hinge model, it could better simulate the components of axial force-bending coupling hysteretic behavior and has higher accuracy. The beam element in general finite element software ABAQUS is based on fiber beam. As the concrete material constitutives which comes with ABAQUS couldn’t simulate the concrete mechanical properties well, the application of fiber beam element in reinforced concrete frame structure is restricted. This paper develops concrete material user subroutine for fiber beam element in ABAQUS which based on user material subroutine interface of ABAQUS. Concrete uniaxial stress-strain relations and rules of loading and unloading conditions are established in the subroutine. By uniaxial tension and compression tests and repeated load hysteresis tests, the subroutine is verified to be reliable. And then, based on the subroutine developed above, this paper operates static elasto-plastic analysis on a three-dimensional frame structure and gets the target performance point of the structure by using the capacity spectrum method. At last, a comparison of the results of static elsto-plastic analysis which obtained in the conditions of different lateral loading force mode is made, and also a discussion of seismic performance of the frame that under different matching bar condition is made in this paper.Through the work done in this paper, the mainly conclusion is listed as following:(l)By the verification, the subroutine of concrete material developed in the paper has high accuracy and convergence. It is suitable for ABAQUS fiber beam element and simulates accurately the nonlinear characteristics of the beam and column elements of the frame structure.(2)In the result of static elasto-plastic analysis, uniform load pattern and parabola load pattern is the upper and lower limits of the pushover curve. The pushover curve under inverted triangle load pattern lies between the other two, and it’s approximate to the pushover curve under parabolas load pattern. Different loading patterns reflect the distribution of inertia force of structures, and it directly influences the results of static elasto-plastic analysis.(3)In the state of big earthquake performance, the matching bar conditions have an evident influence on seismic behavior of the structure, especially improving the reinforcement of the weak story which could improve the seismic behavior significantly. There are two types of ultimate failure form of frame structure:beam hinge damage and column hinge damage, and frame structure with beam hinge damage has a higher bearing capacity and ductility than the one with column hinge damage. The reinforcement should be designed to prevent the structure failure of column hinge damage.