Research On "Strong Column And Weak Beam" Of Prestressed Concrete Under First Aseismic Grade

The seismic performance of prestressed concrete frame structures（hereinafter referred to as the PC frame structure）has been more recognized and widely used in high intensity areas.But for the first grade earthquake-resistant frame structure,the"strong column and weak beam" differential adjustment,the flexural capacity of normal section seismic super common prestressed beam with the adverse conditions will result in difficulties and column reinforcement "strong node weak component".In order to solve the existing problems of the first grade earthquake-resistant frame structure,improve the seismic performance,its application in high intensity area,with reasonable reinforcement in columns should be weakened,allowing the structure to form a "mixed hinge mechanism under rare earthquake,while strengthening the side column,avoid" layer structure formation mechanism".In order to determine the level of PC frame structure with the new "strong column and weak beam " adjustment measures,taking 4 pieces of 8 degrees（0.2g）of different span number and number of the first grade earthquake-resistant plane frame as the research object,based on the OpenSees software,weakening the middle column,control side column longitudinal reinforcement not to yield,elastic-plastic analysis in the 30 earthquake wave earthquake level under the inverse side column coefficient and statistical analysis,has put forward the probability that the coefficient of value.Finally,according to the new adjustment measures,the framework is redesigned and nonlinear analysis is carried out to investigate whether the seismic performance meets the specifications and achieve the desired results.Through the above work,draw the following main conclusions:（1）The specific weakening scheme of the middle column is that the design value of the moment of the middle column is calculated by the formulac ∑M_c=1.7∑M_b except the top of the frame and the axial compression ratio of the column is less than0.15.The design value of the bottom bending moment of the bottom column is also multiplied by the increasing coefficient of 1.7.The reinforcement area of the weakened middle column is greatly reduced,and the purpose of weakening the middle column is achieved.（2）The new moment of side column end coefficient values: except the frame topcorner joints,the design value of the moment of upper floors of side column is calculated by the formulac ∑M_c=η_c·M_bua,flexural strength coefficient of intermediate floors is 1.2,1 layer is 1.4,column bottom bending moment design values increase coefficient of 2.0.（3）Under the rare earthquake,the multi grade PC frame structures designed according to the new adjustment measures can avoid the failure of the whole and the local,and the seismic performance is good.The structure is mainly a hybrid energy dissipation mechanism with a middle column and a prestressed beam hinged out,while the side column is seldom hinged except at the bottom of the bottom column,so as to prevent the structure from forming a layer mechanism".In summary,the new first grade earthquake-resistant frame structure with " strong column and weak beam " adjustment measures which can meet the requirements of the code structure under rare earthquake,and weak in the column,strengthen the side column,improve the structure of energy dissipation performance adjustment.