Evaluation Of The Structural Time-Varying Seismic Performance Based On Pushover

Earthquakes are one of the largest natural disaster to human, people have been committed to developing and improving seismic theory and engineering facilities a long time. In recent years, method of the structure's seismic performance evaluation in foreign countries widely used is nonlinear static analysis method, which is pushover method. However, it has some drawbacks, because it is based on the strength of structural material and components section size reality measured.The realization of the structure's intended function mainly depends on its performance in the throughout service process.In the use process of structure, it is take place of material aging,structural damage,manifested as strength of materials decreased, component cross-sectionalare decreased,which inevitably result in structural damage load force attenuation,affecting the determination of structure's capacity curve. Many scholars are committed to improving this method in order to apply on facilitate in the practicality, but there is no complete and reliable method at times. For this reason, this study was basis on the work of the original, capacity curve established time-varying of even more the actual situation, the establishment methods of evaluation considered time-varying.This paper introduces nonlinear static analysis methods for pushover analysis method of the application in the current nationas.Its basic principle is applied certain force of rules which are distribution with monotonic loading and to progressively increase the level of lateral forceaccording to the structural analysis model. Then modify the structure of the overall stiffness matrix when a component is going into plastic to modify the stiffness (or towithdraw from work)。So cyclica until the structure reached a predetermined state, to assess the seismic performance of structures. The main content: important related theory; basic assumption; basic steps: modeling, loading, capacity spectrum of the two same norm lines, one is from the structure of the (base shear) force - (peak) displacement curve into the capacity of lines, also known as the supply lines, representing the capacity of the structure to resist horizontal forces, the other one is from the acceleration response spectra into acceleration-speed respons aspectra namely ADRS spectrum, also known as the demand for spectrum, on behalf of seismic demand. Will be two lines painted on the one map, known as the performance point, also known as the target displacement point, structural seismic performance point. If the performance point isn't exist, indicates that at earthquake level of demand curve which representative it is, the structure will appear damaged beyond repair or collapse; If the performance point exists, request the damage degree structure at that level under the action of earthquake, which can be the distance between the yield curve point of structural capacity and the performance points divide the distance the yield point to the limit point ratio to find the probability said.,take as the probability .The use of the response spectrum curves of different exceedance probability representative the probability of structures under seismic response to assess the seismic performance of structures. Pushover association the inter-story drift and story drift angle of structure with performance standards such as "normal use, immediately available, life safety, prevented the collapse " evaluate the seismic performance, it is complete and advanced, it is also worth to extent to use. Then introduce SAP2000 analysis software, pushover analysis using SAP2000 the general steps and operation process. Hinge concept, types and specified. View pushover curve and its data.Secondly, appoint the attenuation parameters that affect the carrying capacity drop of building: concrete strength, elastic modulus of concrete, steel cross-sectional area, bar strength and its attenuate law :concrete intensity is diminished grow in initial stage enhances afterward drop gradually; the concrete flexible modulus is decreases gradually ;the bar intensity, cross section invariable first ,drop gradually afterwards.Again hinge concept, types and specified. View pushover curve and its data. According to the transfiguration of hinge when displacement of structure reaches to the performance point, sums up the change law that the beam and column plasticity cuts: concrete intensity change law is diminished grow in initial stage enhances afterward drop gradually; Hinges of the bar intensity, cross section drop gradually.Hinges of all parameter attenuations a bit i in initial stage, start a diminution afterwards.Lastly, law of Seismic performance and it's Evaluation. To determine an attenuation pointe very 5 years. And use SAP2000 examples to pushover analysis at significantly and all the parameters and the respective attenuation points, reaching the structure's interbedded linear and nonlinear displacement,yield force, destroys degree , time-varying curve of the performance point under hackneyed earthquakes and rare earthquake of every structure attenuation point , counts a data draws up a curve together. And Evaluation the Seismic performance by this six indices: As a result of calculating the structure's interbedded linear and nonlinear displacement satisfies the structure's interbedded linear and nonlinear displacement sufferance value that the Seismic criterion respectively;The affection of structure's Seismic performance of attenuations parameter of the concrete intensity is rises a bit in initial stage, afterward decreases gradually; The affection of attenuations parameter of the concrete flexible modulus is decreases gradually, but the extent is not big; The affection of attenuations parameter of bar cross section area and intensity is decreases gradually, but the extent is big . The affection of allof the attenuations parameter is decreases gradually, the maximum amounts to 10.81%.Know of the law that significantly and all the parameters attenuate will reduce the seismic performance of buildings.Because seismic performance of buildings should be subject to attenuation parameters in the actual situation, so it requested that we have to consider attenuation parameters in seismic peformense evaluation . Evaluation of Seismic performance must consider every parameter not neglecte everyone. Have verified to take a thinking that the main viewpoint of this article which Seismic performance of nonlinearity analysis not consider attenuation parameter decays isn't pertinency is correct and necessary.And the structure's yield force, destroys degree , time-varying curve of the performance point under hackneyed earthquakes and rare earthquake in all parameter attenuations situation is the ability curve of time-varying to be equaler with reality changeable.For the existing structure assessment, earthquake evaluation, relief and the improvement seismic design theory provide a scientific basis in a variety of conditions.