Influences Of Moment Magnifying Coefficient On Seismic Performance Of RC Frame Structures

At present, the reinforcedconcrete frame structure has become the most used structural forms in the urban and industrial building.In recent year, lots of the reinforced concrete frame structure were badly damaged in many previous earthquakes. The typical seismic damages manifested that reinforced concrete frame structures broke down because of weak column-strong beam which is completely contrary for current codes in the previous earthquake. Therefore, research on seismic performance of RC frame structure is of great significance.Considering that the earthquake mechanism is a process that uncertainty(structure and earthquake) is coupled with non-linear variables, this paper employs increment dynamic analysis(IDA)method to analyze the earthquake uncertainties. In this paper, Reinforced concrete frame structure with cast-in-place slab is studied by the numerical simulation method. Reinforced concrete frame structures with different moment augment factor of column are discussed of by IDA method and seismic fragility analysis method. Discuss the seismic performance of RC frame structures with different moment augment factor of column at different seismic levels.In response to the failure phenomena that reinforced concrete frame structures fail to realize the “strong column-weak beam” yield mechanism, the main contests are as follows:(1)The paper discusses the key problems that are involved in IDA-based seismic fragility analysis. Then, 16 earthquake records are desired in this paper with a 1S(T,5%) as the indicator for seismic strength and θmax as the indicator for structural damages. Determine the performance level of a reasonable limit state point;secondly, it introduces the finite element modeling theory on Perform3D-based RC plane frame construction and the problems of model design.(2)Depending on different column-to-beam strength ratios, the RC frame structures with and without slabs, which designed with the Chinese seismic codeare established, then doing nonlinear analysis of frame structure of these two types by seismic performance analysis The top displacement, story drift and the distribution of plastic hinges under rare earthquake are studied with dynamic time history analysis. Discuss whether the floor impact when the moment of column increases coefficient on RC frame structural damage mechanisms.(3)Takes the 6-floor RC plane frame construction as the example to elaborate on IDA-based seismic fragility analysis procedure. Finally, it conducts IDA-based seismic fragility analysis on plane frame construction with 13 roof trusses. The reasonable column-to-beam strength ratios are obtained.The paper proposes that is may be appropriate to increase the moment magnifying coefficient value in the subsequent code revision.The results of this paper shows, during the design and analysis of frame structure,the steels in the range of the effective flange width are suggested to take account to bear the bending which endured by the beam, and considering to increase the moment augment factor of column to realize the strong column-weak beam yield mechanism.