Study On Ensuring Failure Mechanism For RC Frames Based On The Beam-column Design Parameters Of The New Code

For cast-in-situ reinforced concrete frame structures,"strong column-weak beam"damage mode is the most ideal. In the wenchuan earthquake, however, this good energyconsumption structure’s performance is "strong beam-weak column" damage mode, mostof the frame structures appears plastic hinge at the end of the column. There are someunreasonable places in the current code for seismic design of buildings. Because there are alot of factors which affect the implementation of the “strong column-weak beam” damagemode, in this paper, the main factors that affect the implementation are elaborated andthese factors are qualitatively analysis. What’s more, the moment amplification factor ofcolumn and stiffness amplification factor of beam are analysised in detail. The mainresearch contents of the paper are as follows:Firstly, the stiffness amplification factor of beam which ensures the strongcolumn-weak beam mechanism for RC frames is studied. Making Pushover analysis in thecases of the third level seismic requirement for regions of7degree, the second levelseismic requirement for regions of8degree, the first level seismic requirement for regionsof9degree respectively. These numerical examples are plane frames. The coefficients are1.8,2.0,2.2and2.4respectively. By comparing the damage mode, story displacement,interstory drift displacement and interstory drift ratio in major earthquakes of the framestructures, we can ensure the reasonable value of the stiffness amplification factor of beam.Secondly, the moment amplification factor of column which ensures the strong column-weak beam mechanism for RC frames is studied. Making Pushover analysis in thecases of the fourth level seismic requirement for regions of6seismicity, the third levelseismic requirement for regions of7degree, the second level seismic requirement forregions of8degree, the first level seismic requirement for regions of9degree respectively.These numerical examples are plane frames. The coefficients are0.8to2.2. In theseismicity regions, the numerical examples contains the original structures. These originalstructures’ moment amplification factor of column are1.2,1.3,1.5,1.7respectively. Bycomparing the damage mode, story displacement, interstory drift displacement andinterstory drift ratio in major earthquakes of the frame structures, we can ensure thereasonable value of the moment amplification factor of column.Finally, According to the above-mentioned the stiffness amplification factor of beamand the moment amplification factor of column which are reference proposal value, theoriginal structures are redesigned. By nonlinear dynamic response analysis and Pushoveranalysis, the damage mode and interstory drift ratio in major earthquakes between theoriginal structures and adjusted structures are studied.According to the analysis of the model, the conclusions are as follows: in the case ofthe fourth level seismic requirement for regions of6seismicity, the ensuring of thestiffness amplification factor of beam and the moment amplification factor of columndepend on the code for design of buildings. In the cases of the fourth level seismicrequirement for regions of7degree, the second level seismic requirement for regions of8degree, the first level seismic requirement for regions of9degree, the stiffnessamplification factor of beam are1.8and the moment amplification factor of column are2.0.In the case of the first level seismic requirement for regions of9seismicity, the momentamplification also is2.2. Through the actual example analysis above-mentioned beam andcolumn design parameters values are reasonable.