【作者】 刘哲；

【导师】 刘云贺；

【作者基本信息】 西安理工大学 ， 防灾减灾工程及防护工程， 2010， 硕士

【摘要】 本文主要探讨了大型渡槽结构体系在强地震作用下,渡槽内水体的大幅度晃动以及水体与槽壁的动力相互作用所形成的强流体固体动力耦合,以及大跨度渡槽结构各支承点跨越不同类型的场地,多支承点不同激励的行波效应问题,得出了一些有意义的结论,为大型渡槽结构的抗震研究提供一定的参考。本文首先采用频率积分法的Trifunac方法对所选的地震波加速度时程曲线来进行0轴修正,消除求解速度时程和位移时程由于积分误差累积造成的基线漂移。为渡槽结构进行地震时程分析做相应的准备。其次,对渡槽结构进行了动力特性分析研究,结构的动力特性主要包括结构的自振频率和振型等一些基本参数。自振频率是结构动力特性的指标,同时也是判别结构是否会发生共振的依据。通过对结构自振特性的分析判断了渡槽结构模型的合理性。最后对渡槽内的水体应用任意拉格朗日一欧拉法进行了流固动力耦合的非线性描述,将渡槽的支撑点与非支撑点分别考虑,建立了渡槽结构一致地震输入模型和多点地震输入模型,分析了强地震作用下渡槽内水体的大幅晃动,渡槽结构的不同支撑点的输入具有时间差效应的多点输入问题对渡槽结构的影响。分析结果表明：1、结构与流体之间的相互作用就会使结构产生类似于TLD(调谐液体阻尼器)的效应。这样渡槽内的水体能给结构提供更大的阻尼,改善结构的能量耗散,与空槽模型相比能够明显的减小结构的最大位移。2、不同波速的多点地震输入都对大跨度渡槽的动力响应有着明显的影响,不同的输入使得槽内的水体晃动幅度减小,但结构中的应力分布却明显增大,主要是各支撑点地震输入时间间隔变化,导致跨端截面底面中心两端点的相对位移变化,地震波速越小时,引起的应力变化越大,由于渡槽是一种重要的输水建筑物,当相邻跨处两渡槽横截面相对位移过大时,会造成伸缩缝止水橡胶带的破裂,从而大量漏水,危及渡槽的安全。在渡槽设计时应充分考虑这一因素对渡槽的影响。本文考虑不同的过水深度并建立一致地震输入模型和多点地震输入模型,分析结果表明：1、随着渡槽内水体增加时,渡槽结构跨中截面的最大位移是先减小后增大；当槽内无水时,跨中截面的位移值最大；这因为计算模型考虑了流体、固体之间的相互作用,当输入的地震波速越小,结构两端所受到激励间隔的时间就越长,结构与流体之间的相互作用就会使结构产生阻尼效应。这样渡槽内的水体能给结构提供更大的阻尼,改善结构的能量耗散,能够明显的减小结构的最大位移；2、随着渡槽内水体增加时,渡槽结构跨端截面的最大位移是随之增大；这是由于随着水位的增加,渡槽结构的上部质量增大,从而使作用槽体上地震作用增大的缘故；当槽内无水时,跨中截面的位移值最小；这是因为渡槽结构的槽体与槽墩采用铰接的处理的方法,地震动时结构和流体相互作用降低了渡槽结构的动力响应；所以通过以上分析可知,在对像渡槽这种大跨结构进行抗震分析时,应该考虑不同过水深度在地震作用下对结构所产生的影响。更多还原

【Abstract】 This thesis discusses the large-amplitude sloshing water of the large-scale flume that is under strong earthquake and fluid-solid dynamic coupling effect which caused by interaction of flume’s sloshing water and sidewall. This paper also studies the travelling wave effect under different situation such as long-span flume’s supporting points standing on different types of ground and multi-support point excitation. At the end, it comes with some meaningful conclusions that providing a reference for the study of aseismatic design of large-scale flume.First of all, it takes the Trifunac method of Frequency Integral for O-axis modification about time-history curves of earthquake’s acceleration, which avoids baseline drifting caused by accumulated integration error when calculating time-hisory of speed and displacement. It makes preparation for taking time-history analysis of flume.After that, it takes analysis of dynamic characteristics of flume, which contains some essential parameters of natural frequency and mode of vibration. Natural frequency is not only the index of structural dynamic properties but also the basis of judging whether the structure would be in resonance. It assesses the rationality of flume’s structural model through analyzing the characteristics of natural frequency.It takes Lagrange-Euler method to describe the water in the flume that is under fluid-solid dynamic coupling as nonlinearity. Then, considers supporting and non-supporting points for consideration respectively and creates flume model of uniform and multiple-support excitation. It analyses the large-amplitude sloshing water in the aqueduct and multi-support excitation’s time difference effect on flume.It shows that:First, the interaction of structure and fluids could make the structure produce an effect that is similar to TLD. As a result, the water in the flume could afford more damping force and improve the efficiency of energy dissipation. So compared with empty flume model, it can reduce maximum displacement obviously. Secondly, Multi-support input with different speed waves has obvious effect on long-span flume’s dynamic response, and different inputs reduce the sloshing amplitude but increase the stress distribution on the structure. The mainly reason about relative displacements’change of cross-section’s both ends of the bottom is that interval of multi-input is changed. The stress change that caused by earthquake increases along with the decreases of the earthquake wave speed. Flume is a crucial conveyance structure, the rubber waterproofing strap of two flumes’ cross section will be torn up when relative displacement is too large. And this will cause severely leaking that would endanger the safety of flume. Consequently, this factor should be taken full account of in designing.Investigations of different water depth through single-support earthquake input models and multi-support earthquake models have been conducted in this research, the result has shown that firstly, as the water body increases in the flume, the maximum displacement of mid-span section in the plume declined first then increased subsequently, and the displacement of mid-span section of the plume reaches its maximum value when there is no water body in the flume. This is mainly because the interaction effect of fluid and solid was taken into consideration in the simulating model, which the excitation intervals received between two ends of the structure became longer as the decrease of the input earthquake wave speed, that the interaction between system and the fluid induced a damping effect to the system, thereafter the water body in the flume provided more damping onto the system, ameliorating the energy dissipation of the whole system, which significantly reduced the maximum displacement of the system. Secondly, as the water body increases in the flume, the maximum displacement of mid-span section in the plume declined first then increased subsequently also caused by the reason that as the water level increases, the weight of the upper part of the flume raises, that enhanced the earthquake effect on the functional flume. The displacement value of mid-span section of the flume drop to its minimum value when there is no water in the flume, that is because the flume and its slot buttress are connected using the method of hinge joint, which diminish the dynamic response of the plume by the co-action effect of the system and the fluid. From all discussed above, a conclusion can be obtained that when analyzing the anti-seismic issue for high-span system like flumes, the influence on such system during earthquake under different water depth should be taken into consideration.更多还原