Study On Seismic Appraisal Method Of Irregular Plane RC Frame Based On The Principle Of Equal Transcendence Probability

China’s current national seismic evaluation standard,GB50023-2009,is not perfect in the value theory of seismic action in the seismic calculation of existing buildings,and lacks clear probability significance.Moreover,the standard has been issued and implemented for more than ten years,and some of its provisions are no longer applicable with the development of time.In this paper,based on the 89 series of aseismic design codes,the L-type irregular frame structure with plane layout designed in the 8-degree（0.2g）aseismic fortification area is taken as the object to study the aseismic appraisal method.In this paper,two kinds of space frame models with irregular concave and convex indexes of 0.286（under the limit）and 0.444（over the 0.3 specified in the code）are designed according to the seismic fortification requirements of 8 degrees（0.2g）according to Code for seismic design buildings（GB 50011-2010）and the seismic appraisal method of equal transcendence probability.Using Sausage,the nonlinear analysis software,the elastoplastic time history analysis of the model designed according to the current code under the action of rare level earthquake is carried out,and the elastoplastic time history analysis of the model designed according to the principle of equal transcendence probability is carried out under the action of rare level earthquake reduced according to the principle of equal transcendence probability.According to the analysis results,the equal transcendence probability method is improved,and the space frame model is redesigned according to the improved equal transcendence probability method,and the comparison analysis is carried out with the software Sausage.The main conclusions are as follows:（1）Under the action of rare level earthquake reduced by the principle of equal transcendence probability,the frame structure designed according to the equal transcendence probability method before improvement(the reduction coefficient of the first level horizontal earthquake influence coefficientα_max is 0.719)has no overall damage and local damage,and achieves the seismic fortification goal of No Collapsing in the Strong Earthquake.However,the seismic response is greater than that of the new buildings designed according to the current code,and the overall performance is the energy consumption mechanism mainly based on the hinge at the column end.Before improvement,the method can not meet the technical requirements of seismic appraisal.（2）Improve the equal transcendence probability method by changing the reduction coefficient of the first level horizontal seismic influence coefficientα_max from0.719 to 0.86 which is the same as that of the third level.Under the condition of the first level earthquake resistance,the seismic response of the building which is designed by the improved method is slightly less than that of the new building designed according to the current code,and the overall performance is the energy consumption mechanism of mixed hinge,which is obviously improved compared with that before the improvement;In the second level seismic condition,the seismic response is slightly greater than the new building level,but less than the results before the improvement.Although the overall energy consumption mechanism is still mainly the hinge at the end of the column,the hinge ratio of the beam and column is significantly increased compared with that before the improvement,which is close to the level of the new building.The improved method can meet the technical requirements of seismic appraisal.（3）The improved equal transcendence probability method can meet the expectation that the seismic performance of new buildings is equivalent when the equal transcendence probability principle is applied to reduce the rare horizontal earthquake action.It is proved that the improved method can be applied to seismic appraisal.（4）The results of examples from this article show that when the concave convex index of plane irregular frame structure is not more than 0.45 and the floor height is not more than 30m,the inter story displacement ratio is not more than 1.5,and the degree of torsion is not large,so the frame structure is suitable for the seismic appraisal method with equal transcendence probability.