Comparison Reasearch On Moderate And Minor Earthquake Of RC Frame Structure Based On Component Deformation Performance Evaluation

The performance-based seismic design method is currently at the forefront of the international seismic design field,and the idea is reflected in the seismic design specifications of countries and regions such as the United States,Japan,Australia,new Zealand and Europe.Current Chinese codes also put forward the concept of “structure seismic performance design”,but there are still many imperfections.At present,China uses minor earthquakes for structural seismic design,but the moderate earthquakes are used as “fortification intensity earthquakes”.In addition,foreign mainstream seismic codes use earthquakes with a 50-year surpassing probability of 10% as design earthquakes,which is equivalent to the level of moderate earthquakes in China.It can be seen that the moderate earthquake design has certain rationality.As a key part of performance-based seismic design in Chinese codes,the moderate earthquake design must be given enough attention.This paper compares the contents of the minor earthquake design and the moderate earthquake design in detail.The relevant specifications include Code for Seismic Design of Buildings(GB50011-2010),Technical Specification for Concrete Structures of Tall Buildings(JGJ3-2010)and the industry standard of Guangdong Province Technical Specification for Concrete Structures of Tall Buildings(DBJ15-92-2013).The research contents and main conclusions are as follows:(1)Summarize the performance design of moderate earthquake and conventional design of minor earthquakes,compare the combined expressions of seismic load effects of various codes,discuss the principle of value of each parameter in the formula,and study the influence of different design methods on the bearing capacity demands of frame beams and frame columns.(2)Establish 18 sets of YJK typical RC frame structure models with different structural heights,fortification intensity and site soil types.Each group is designed according to three methods: minor earthquake design,JGJ3-2010 moderate earthquake design and DBJ15-92-2013 moderate earthquake design.It is found that moderate earthquake design of the RC frame structure will lead to an increase in the section size of the beam and column members and an increase in the reinforcement of the longitudinal bars.(3)Import 54(18×3)structural models into PERFORM-3D finite element software,use the fitting coefficient method to select 14 seismic waves for each structure,and analyze the elastoplastic time history of the structures under rare earthquakes.The distribution law of shear span ratio and bending-shear ratio is obtained.The seismic performance evaluation method of RC structure based on component deformation is used to compare the performance changes of the members,and it is found that the structures meet the fortification requirements of “no callapse under rare earthquakes”.The performance of frame columns designed by the moderate earthquake and the small earthquake is similar,but the performance of frame beams of the moderate earthquake design is better than that of the small earthquake design.(4)On the basis of rare earthquake PGA,the seismic force is continuously increased.With the first vertical member failure criterion adopted as the foundation of structural collapse,the collapse vulnerability analysis of the structure is carried out based on the IDA method.It is pointed out that the RC frame structure designed by the three methods has a strong relationship of anti-collapse capability: DBJ15-92-2013 moderate earthquake design > JGJ3-2010 moderate earthquake design > minor earthquake design.However,when the number of structural layers is large,the site soil conditions are poor,and the seismic fortification intensity is high,the use of the moderate earthquake design will reduce the collapse resistance of the structure.