The Effect Of Column-to-Beam Strength Ratio On Seismic Performance Of RC Frame Structure

"Strong column-weak beam" is one of the important concepts of RC frame structure seismic design.The results show that under the action of earthquake,the beam of frame structure yields first can make the whole structure have better ductility and energy dissipation ability.The seismic design code of our country also puts forward corresponding measures to ensure that the RC frame structure can realize the failure mechanism of "strong column-weak beam" under earthquake.However,in postearthquakes,the RC frame structure designed according to the code rarely appears the failure mechanism of "strong column-weak beam" as expected by the designer,and most of the structures have plastic hinges on the column section before the beam section,which leads to the collapse of the structure.In order to solve this problem,the effect of column-to-beam strength ratio augmentation factors on seismic performance and failure mode of RC frame structures is studied.And the suggested value of column-tobeam strength ratio is given.The main research contents are as follows:(1)According to the code of our country,a 3-story RC frame structure with slab is designed,the reinforcement of beam is kept unchanged,and column-to-beam ratio is equal to 1.2,1.4,1.6,1.8 and 2.0 by changing the reinforcement of column.Medium joints at the bottom of the column base are taken to carry out reversed cyclic loading with different column-to-beam ratio and axial compression ratio.By analyzing the hysteresis characteristics,energy dissipation capacity,yield mechanism and skeleton curve of the components,the effect of column-to-beam strength ratio and axial compression ratio on failure mode of beam-column joint is studied.(2)In order to avoid the contingency of the calculation results of a single structure,the 6-story and 9-story RC frame structures with slab are designed according to the code of our country,the reinforcement of beam is kept unchanged,and column-to-beam ratio is equal to 1.2,1.4,1.6,1.8 and 2.0 by changing the reinforcement of column.Pushover analysis is carried out for 3 RC frame structures respectively,and the effect of column-to-beam strength ratio on the integral seismic capacity and failure mode of the structure is analyzed through the capability curve,the story drift,the absolute seismic capacity and the yield mechanism.(3)44 far-field non-pulsed ground motions and near-field pulsed ground motions are selected respectively,and their amplitudes are adjusted according to four earthquake magnitudes of frequently,fortification,rare and extremely rare.And then the dynamic time history analysis of 3 RC frame structures are carried out.The response of the structures under near-field pulsed ground motions and far-field non-pulsed ground motions was studied.The IDA and seismic vulnerability analysis of structures is carried out to study the effect of the column-to-beam strength ratio on the collapse resistance of the structures.