竖向地震作用对框架—核心筒结构抗震性能的影响

发布时间：2019-03-07 09:00

【摘要】：地震工程的传统观点认为：水平地震作用是引起结构破坏的主要原因，竖向地震力则微不足道。但是大量地震记录表明，竖向地震作用比较明显，大量的震害现象也很难用传统的观点来解释，而以竖向地震力的影响来解释比较合理，但是仍有不少学者对这种观点提出了质疑，，所以竖向地震作用对于结构抗震性能的影响需要更进一步的研究。本文采用PERFORM-3D软件建立结构分析模型，首先采用振型分解反应谱法分别计算结构在工况1单向水平地震作用和单向加竖向地震作用，工况2水平双向地震作用和和三向(水平双向和竖向)地震作用下结构的地震反应情况，水平双向地震输入采用规范建议的比值X:Y=1:0.85，三向地震输入比值取X:Y:Z=1:0.85:0.65，结果表明竖向地震作用对于结构的水平位移基本没有影响，而对框架梁跨中竖向位移影响较大，竖向地震对框架柱轴力影响明显，墙肢轴力增幅较小，而且框架梁跨中弯矩和梁端弯矩在竖向地震作用下都明显增大。为了进一步分析竖向地震作用的影响，本文进行了结构的弹塑性地震反应分析，分析在两种工况下结构的反应。选择了EL centro波、TAFT波和天津波三条典型的强震记录，结果与振型分解反应谱法相吻合。三向地震输入和双向地震输入顶点位移的时程曲线基本相符合，两种工况下层间位移角曲线也基本吻合，即竖向地震作用对结构水平位移影响很小，而结构框架柱、剪力墙轴力变化剧烈，柱轴力最大增幅66.1%，且柱中都出现拉力，这样原来压弯、压剪的受力状态变成了拉弯、拉剪，对于构件的承载力降低明显，受力不利，结构的抗震设计应该对于这种情况有所考虑。跨中弯矩和梁端弯矩在竖向地震作用下剧烈波动，正负交替出现，均比无竖向地震时增大很多，竖向地震加快了框架梁的变形发展，跨中竖向位移增量也很明显。结果表明，对于竖向地震作用不能忽视，规范中对竖向地震的简单规定值得进一步研究，竖向地震动对结构抗震性能影响的研究工作还需要更全面更深入的研究。
[Abstract]:The traditional view of earthquake engineering is that horizontal seismic action is the main cause of structural damage, while vertical seismic force is negligible. However, a large number of seismic records show that the vertical seismic action is relatively obvious, and a large number of earthquake damage phenomena are difficult to be explained from the traditional point of view, but it is more reasonable to explain the effects of vertical seismic forces. However, many scholars have questioned this point of view, so the effect of vertical seismic action on seismic performance of structures needs to be further studied. In this paper, the PERFORM-3D software is used to establish the structural analysis model. First, the modal decomposition response spectrum method is used to calculate the unidirectional horizontal seismic action and the unidirectional plus vertical seismic action of the structure under condition 1, respectively. In case 2, the horizontal bi-directional seismic action and the seismic response of the structure under the action of three-way (horizontal-directional and vertical) earthquakes, the horizontal bi-directional seismic input shall adopt the recommended ratio of X, Y, 1, and 0.85 for the horizontal two-way earthquake. The results show that the vertical seismic action has no effect on the horizontal displacement of the structure, but the vertical displacement of the frame beam has a great influence on the vertical displacement in the span of the frame beam, and the three-way earthquake input ratio is 0.85 脳 0.65, which shows that the vertical seismic action has no effect on the horizontal displacement of the structure. The effect of vertical earthquake on axial force of frame column is obvious, and the increase of axial force of wall limb is small. Moreover, the moment of middle span and the moment of beam end of frame beam obviously increase under the action of vertical earthquake. In order to further analyze the influence of vertical seismic action, the elasto-plastic seismic response of the structure is analyzed in this paper, and the response of the structure under two kinds of working conditions is analyzed. Three typical strong earthquake records, EL centro wave, TAFT wave and Tianjin wave, are selected. The results are in good agreement with the modal decomposition response spectrum. The time-history curves of three-way earthquake input and two-way earthquake input peak displacement basically accord with each other, and the displacement angle curve between the two conditions is basically consistent, that is, the vertical earthquake has little effect on the horizontal displacement of the structure, while the frame column of the structure has little influence on the horizontal displacement of the structure. The axial force of shear wall changes violently, the maximum increase of axial force of column is 66.1%, and the tension appears in the column, so that the original compression and bending, the stress state of compression and shear become tension bending, tension and shear, the bearing capacity of the member is obviously reduced, and the stress is unfavorable. This situation should be taken into account in the seismic design of structures. The mid-span moment and the beam end moment fluctuate violently under the action of the vertical earthquake, the positive and negative alternately appear, both increase a lot more than without the vertical earthquake, the vertical earthquake accelerates the deformation development of the frame beam, and the increment of the vertical displacement in the span is also obvious. The results show that the vertical seismic action cannot be ignored, and the simple regulation of vertical earthquake in the code is worthy of further study, and the research work on the influence of vertical seismic motion on the seismic performance of structures needs more comprehensive and in-depth study.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU973.31

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