Seismic Design Of Rc Frame Columns Considering The Random Characteristics Of Eccentricity And Its Influence On The Ductility Of The Structure

The investigation report on the earthquake damage of Wenchuan earthquake.The damage of column end of RC frame structure is more serious than that of beam end,The failure mode presents the "strong beam weak column" of the frame structure.But the failure mode of "strong column and weak beam",which is expected in the seismic design of building structure in our country is rarely happen,the relevant studies indicated that the appearance of this kind of "weak column" phenomenon is related to the low reliability of the design of the RC frame column;After considering the random characteristic of eccentricity,Under the combination of several main parameters,According to the present method,the seismic reliability of RC frame columns will be greatly changed.At present,the research work of this aspect has not been paid enough attention,In this paper,the corresponding research on this problem is carried out,The finished core work can be summarized as follows:(1)The research object is selected as the research object of the reinforced concrete rectangular section large eccentric compression frame column,According to the calculation formula of bearing capacity in seismic code of our country,a nonlinear failure equation considering the stochastic characteristic of eccentricity is established.Using Matlab program to consider the stochastic properties of the main factors,such as the gravity load,the horizontal earthquake action,the concrete strength and the strength of the steel bar which are considered in the nonlinear limit state equation,then the Carlo Monte method is used to calculate the reliability value of the frame column in the case of moment increasing coefficient at different column ends,And considering the condition of the reinforcement ratio in 1%-4%,The reasonable value of the seismic adjustment coefficient of the bearing capacity is determined under the condition of the moment increasing coefficient at different column.(2)According to the current carrying capacity of the standard seismic adjustment coefficient and the improvement of the bearing capacity of the seismic adjustment coefficient of the frame column reinforcement calculation,the corresponding frame structure contrast model is obtained.Pushover analysis was carried out by using OPENSEES finite elementsoftware,the capacity curve of frame pushover under different load carrying capacity is obtained.Then the failure mode of the model is obtained by the data processing which is according to the pushover analysis of the frame structure at the bottom of the shear vertex displacement curve,The pushover capacity curve is converted to the two line by the equal area method to calculate the frame structure of the ductility coefficient.Through the failure modes and ductility analysis of frame structures,we have get some suggestions on seismic design of RC frame structures.