Nonlinear Finite Element Analysis Of RC Frame Structure Based On OpenSEES

Reinforced concrete frame structure has flexible and diverse layout, and its forcetransfer mechanism is also clear and concise, therefore RC frame structure is used inmultistory and high rise building commonly, and it is widely used in the earthquakefortification area for its high load capability, good ductility and entirety. So researchon anti-seismic performance of RC frame structure has important significance. Thenonlinear element analysis method which based on finite element analysis software iswidely used as an effective and practical research tool in the field of earthquakeengineering.In this thesis, based on the correlative researches at home and abroad, severalaspects are studied as follows:1、Firstly, a brief discussion on fundamentals of stiffness-based and flexibility-based fiber beam-column elements is carried out. Then, based on the analytical resultsof a RC cantilever column, the divided methods for a member are suggested: for DBelement, a member should be divided into five or more elements, for FB element, oneelement is enough; for both DB element and FB element, one element should have atleast four section integration points; for DB element, FB element and HB element, thesection should be divided into6×6fiber mesh or denser.2、Based on OpenSEES, a RC frame structure test is simulated, what’s more, thesimulation results are highly consistent with the experimental results which thus helpto verify the accuracy of the model. And some other conclusions are drawn: theeffects of the steel bar hardening should be ignored when creating a numerical modelof a RC frame structure; the best numerical model for the simulation of beam-columnjoints is fiber beam-column element combined with beam-column joint element; foran overall RC frame structure the fiber beam-column element is good enough.3、The effects of the axial compressive ratio, reinforcement rate of columns andcast-in-situ floor slabs on the ductility and capacity of energy dissipation of the RCframe structure are analyzed by using static analysis method. The results show thatwith the reduction of the axial compressive ratio of the columns, the ductility ofdisplacement gets improved; but the reduction of the reinforcement rate leads to theopposite result, at the meanwhile, the capacity of energy dissipation of the RC framestructure gets reduced; the influence of the cast-in-situ floor slabs also degrades the ductility and the capacity of energy dissipation of the RC frame structure and theadverse effects aggravated with the increase of effective flange width values.4、Based on transient analysis method, the effects of the axial compressive ratioof columns, cast-in-situ floor slabs and the cross section dimension of beam on theseismic performance of the RC frame structure are investigated. Through this research,we have substantial reasons to believe that: reducing the load level of the column isbenefit for the seismic performance of the frame; the cast-in-site floor slabs and largercross section dimension of beam can lead to the “strong beam, weak column” failuremode and weak-layer failure of the RC frame structure.