Torsional-resistance Design And Study On Seismic Collapse Reliability Based On Double Random Of Frame-Shear-Wall Isolated Structure

When the plane irregular frame-shear-wall structure was subjected to seismic action,usually due to the center of mass didn't coincide with the rigid heart,would produce significant torsional deformation,might be more serious damage,or even collapse.In this paper,the method of seismic fragility analysis for plane irregular structures was proposed based on the characteristics of inter story displacement and torsional displacement.The seismic behavior of plane irregular structures became clear.On this basis,the paper put forward the torsional design method of isolated structures.The reliability of lateral incremental collapse,vertical progressive collapse and lateral progressive collapse of isolated structures was analyzed by using reliability analysis method based on seismic overall damage model.The main contents of this paper were as follows:1)Collapse vulnerability analysis of plane irregular structures based on double indexesA method of seismic vulnerability analysis for plane irregular structures was proposed.Wavelet transform coefficient method in MATLAB was used to identify the most unfavorable input direction of ground motion;Took into account the correlation and randomness between the quantitative indexes,used the method of calculating the exceedance probability,the inter story displacement angle,the inter story torsion angle and the exceedance probability in the double index limit state were calculated respectively.The comparative analysis shows that the input angle of ground motion cannot be ignored for the seismic performance of plane irregular structure.When analyzing the vulnerability of plane irregular structure,the effects of the inter layer displacement and the inter layer torsion angle should be taken into account to prevent the overestimation of the seismic performance of the structure.The vulnerability analysis method based on double indexes is more safe and reliable for the evaluation of the seismic performance of the plane irregular structures.2)Torsional design method of plane irregular base isolated frame shear structureA method for torsional control of plane irregular frame shear isolation structures was proposed.Did seismic isolation design for structures with different eccentricity.By adjusting the relative position between the rigidity center of isolator layer,the mass and rigidity center of upper structure,the method for torsional control of plane irregular isolation structures was obtained.The results show that: 1)for the symmetric structure or small eccentric structure,make the mass center of upperstructure and the rigidity center of isolator layer coincided as far as possible so as to control the torsion of the isolator layer.2)for large eccentric structure,the torsional displacement ratio of isolator layer should be less than 1.2,make the rigidity center of the isolator layer and the rigidity center of the upper structure are respectively positioned on both sides of the mass center of the isolator layer,so as to control the torsion of the upper structure.3)Seismic overall damage model of base isolated frame shear structure based on multi parameterBy the introduction of the component importance index,a seismic overall damage model of isolation structure was proposed,which took into account the important degree of the components.The study shows that the seismic overall damage model considering the important degree of the components can also reflect the influence of component plastic accumulative damage degree and component important degree on the whole damage.Making use of this damage model is more safe and reliable to evaluate the seismic performance of the isolated structure under the action of strong earthquake.4)Study on the reliability of lateral incremental collapse of base isolated frame shear structure based on the seismic overall damage modelA reliability analysis method based on the seismic overall accumulative damage model was proposed for the frame-shear-Wall isolated structure.Considering the randomness of structure and seismic wave,Latin hypercube sampling was used to form the sample space.The dynamic non-linear analysis of each sample was carried out.Based on the seismic overall damage model of the isolated structure,the cumulative damage index of the upper structure and isolator layer were calculated respectively.The seismic reliability of structural seismic collapse limit state was analyzed by quadratic fourth-order moment method,and the exceedance probability of lateral incremental collapse of structures under earthquake was obtained.5)Reliability analysis of vertical progressive collapse of base isolated frame shear structure under earthquakeBased on the seismic damage model of the isolation bearing,the most susceptible isolation bearing under earthquakes was obtained.Then,based on the parameter randomness of the damage structure,the vertical progressive collapse load coefficient of the damage structure was obtained by using the vertical stochastic dynamic incremental analysis method.Took the load coefficient as the overall performance index,the probability of vertical progressive collapse of the damaged structure was obtained by using the quadratic fourth-order moment method.Research shows that analysis the reliability of the vertical progressive collapse of thebase isolated frame shear structure by using the reliability theory,the vertical progressive collapse probability of the damaged base frame-shear-Wall isolated structure under the action of earthquake can be obtained intuitively.And provide a reliable basis for structural design and post-earthquake reinforcement.6)Reliability analysis of progressive collapse of base isolated frame shear structure subjected to series of ground motionsFor the base isolated frame shear structure,the earthquake may lead to the failure of the isolation bearing,when the damaged structure experienced aftershocks once again,it may produce three failure modes: the first is the lateral collapse of the structure due to the failure of the isolator layer;the second one is the lateral progressive collapse of the structure due to the failure of the upper structure;the third one is the vertical progressive collapse due to the failure of the damaged beam.The collapse probability is related to the ground motion intensity of the main and the aftershocks.The collapse modes of the damaged structures are different under different failure positions of isolation bearing.