深水圆截面桥墩地震响应的分析与试验

发布时间：2018-04-21 13:00

本文选题：Morison方程 + 振动台试验　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着经济的快速发展,一大批大跨度深水桥梁相继建成。相比于处于内陆的桥梁,深水桥梁所处环境更加复杂,不仅会遭受强风荷载,还会受到地震作用。当处于深水中的结构遭受地震作用时,水-墩相互作用而产生的动水压力不仅会改变结构的动力特性,还会改变其动力响应。因此,对于深水桥墩的地震响应研究有很重要的理论与应用意义。为真实的模拟海底地震作用机理,本文对水箱结构进行了设计,水箱由刚性基础支承于地面,并通过水平连接板与振动台连接,以达到水箱向振动台只传递水平荷载,不传递竖向荷载的目的,并通过自行设计的水箱完成了振动台模型试验。本文通过试验实测加速度值,对Morison方程中的附加质量系数与附加阻尼系数进行了测定。并研究了附加质量系数与附加阻尼系数与结构入水深度比、长细比、雷诺数三个参量的关系。研究发现,附加质量系数随着结构入水深度比的增大而增大。附加质量系数与附加阻尼系数随着雷诺数的增大而减小。而针对附加质量系数与附加阻尼系数在负数区间波动的现象,可以解释为圆柱结构从水中吸收了一定能量,引起了自身的不稳定造成的。但截至目前为止,还没有一种完备的理论模型可以对这一现象进行分析,有待相关学者进一步探究。本文选取墩底最大剪力、墩底最大弯矩、墩顶最大位移三个基本参量,利用有限元软件Workbench对桥墩结构进行动力响应分析。研究发现:(1)对于同一直径的圆形截面单墩,结构的动力响应随着地震动峰值加速度的增大而增大。对于不同直径的圆形截面单墩,地震动水效应对桥墩墩底最大弯矩有增大效应,而对墩顶最大位移却有减小的趋势。(2)随着长细比的增大,桥墩结构墩底最大剪力与墩底最大弯矩都有明显的增大趋势,而墩顶最大位移幅值却先增大后减小,其值最后小于无水单墩。说明水的存在会改变结构的动力响应,但未必都是增大效应。通过对比数值计算与试验得到的墩顶加速度时程曲线发现两者趋势基本相同,其中试验实测得到的加速度峰值为0.96g,而数值模拟所得到的加速度峰值为0.82g,两者误差为14.58%。
[Abstract]:With the rapid development of the economy, a large number of long-span deepwater bridges have been built one after another. Compared to the inland bridges, the environment of the deep water bridge is more complex, not only will suffer strong wind load, but also be subjected to earthquake action. When the structure in deep water is subjected to seismic action, the dynamic water pressure produced by water pier interaction will not only change. The dynamic characteristics of the structure will also change its dynamic response. Therefore, it is of great theoretical and practical significance to study the seismic response of the piers in deep water. For the real simulation of the mechanism of the seabed seismic action, the water tank structure is designed. The water tank is supported by the rigid foundation on the ground surface and connected by the horizontal connecting plate to the vibrating table. The water tank passes the horizontal load only to the vibrating table, does not transfer the vertical load, and completes the shaking table model test through the self designed water tank. In this paper, the additional mass coefficient and the additional damping coefficient in the Morison equation are measured by testing the measured acceleration values. The additional mass coefficient and the additional damping system are studied. It is found that the additional mass coefficient and the additional damping coefficient decrease with the increase of the Reynolds number, and the additional mass coefficient and the additional damping coefficient fluctuate in the negative interval, and the additional mass coefficient and additional damping coefficient decrease. It can be explained that the cylindrical structure absorbs a certain amount of energy from the water and causes its own instability. But so far, there is not a complete theoretical model that can be used to analyze this phenomenon. The maximum shear force of the bottom of the pier, the maximum bending moment of the bottom of the pier and the maximum displacement of the pier top are selected in this paper. Three bases are selected in this paper. The dynamic response of the pier structure is analyzed by the finite element software Workbench. It is found that: (1) the dynamic response of the structure increases with the increase of the peak acceleration of the ground motion for the single pier with the same diameter. For the single pier with different diameter, the earthquake dynamic water effect increases the maximum bending moment of the pier bottom. The maximum displacement of the pier has a tendency to decrease. (2) with the increase of the length and length, the maximum shear force of pier bottom and the maximum bending moment of pier bottom all have a obvious increase trend, but the maximum displacement amplitude of the pier top increases first and then decreases, and its value is less than that of the single pier without water. It is indicated that the existence of water will change the dynamic response of the structure, but not the dynamic response of the structure. It is necessary to increase the effect. By comparing the acceleration time curve of the pier top acceleration obtained by numerical calculation and test, it is found that the two trends are basically the same, of which the peak acceleration of the acceleration is 0.96g, and the peak of the acceleration is 0.82g, and the error is 14.58%.

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55

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