脉冲型近断层地震作用下深水桥墩动力响应特性研究

发布时间：2018-01-28 12:22

本文关键词： 深水桥梁等效单墩近场地震远场地震速度脉冲脉冲参数动水压力地震动响应　出处：《北京交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：地震作用下,由于动水和深水桥梁水中部分的动力相互作用,势必显著改变桥梁的振动特性和地震响应,而不同的地震动类型以其独特的频谱特性,有可能会对桥梁的动力行为产生不同的影响。脉冲型近断层地震下深水桥梁的动力响应特征,是深水桥梁抗震设计中有待研究的重要科学问题。本文采用基于流固耦合理论的势流体动力数值算法,以典型铁路深水桥梁的等效单墩模型为对象,开展了如下研究工作： (1)采用基于流固耦合理论的势流体计算方法,借助ADINA有限元软件进行地震作用下水中桥墩的流固耦合动力分析。对比研究了近场和远场地震荷载激励下桥墩的动力响应响应特性,分析动水效应对矩形、圆形两种不同截面形式的等效单墩结构的振动特性和地震动响应的影响程度,并对半解析的Morison方程法进行了对比检验。结果表明：随着水深的增加,桥墩自振周期不断延长。与无水环境下相比,动水压力的存在使得桥墩结构的地震响应变化显著,并且近场地震作用下桥墩结构的动力响应明显大于远场,因此对于近断层区域的深水桥梁的抗震设计应给予关注。 (2)在近、远场地震激励下深水桥墩的动力响应计算基础之上,对作用于矩形、圆形两种不同截面形式桥墩的动水压力分布规律以及总动水压力特性进行对比分析,并与我国铁路、公路规范以及日本规范中的动水压力计算方法进行了检验。总体而言,地震作用下,深水桥墩结构所受到的动水压力随着水深的增加而不断增大；动水压力沿桥墩高度是先增大后减小的抛物线型分布。通过对各规范算法的检验可知,日本规范规定的总动水压力值偏大而中国公路规范规定的总动水压力偏小；对于分布动水压力,近场地震下,对于矩形截面桥墩,两规范动水压力估计不足；而对于圆形截面桥墩,日本规范偏于保守,铁路规范结果较为接近。远场地震下,两类规范算法的动水压力都偏于保守。 (3)采用人工合成近断层脉冲型地震动的方法,定量分析脉冲峰值Vp、脉冲周期Tp、脉冲类型三类代表性速度脉冲参数对矩形、圆形两种截面形式深水桥梁动力响应的影响。结果表明：在人工合成近场脉冲型地震动作用下,深水桥墩结构的地震动响应比无脉冲时有较大的增加,并且脉冲峰值Vp、脉冲周期Tp、脉冲类型,这三类脉冲参数对深水桥墩地震动响应影响显著。脉冲峰值Vp对深水桥墩地震动响应的影响程度随着Vp的增加而不断增大；当脉冲周期接近桥墩结构的自振周期时,Tp对深水桥墩地震动影响最大；在深水桥墩结构自振周期变化范围内,C类脉冲对深水桥墩地震动响应影响最大,B类次之,A类最小。
[Abstract]:Because of the dynamic interaction between the dynamic water and the underwater part of the deep water bridge, the vibration characteristics and the seismic response of the bridge will be changed significantly under the earthquake action, and different types of ground motion will have their unique spectral characteristics. The dynamic response characteristics of deep water bridges under impulsive near-fault ground earthquakes are important scientific problems to be studied in seismic design of deep water bridges. In this paper, the potential hydrodynamic numerical algorithm based on the fluid-solid coupling theory is used to study the equivalent single-pier model of typical deep-water railway bridges as follows: 1) the potential fluid calculation method based on fluid-solid coupling theory is adopted. The fluid-solid coupling dynamic analysis of bridge piers under seismic action is carried out by means of ADINA finite element software, and the dynamic response characteristics of piers under near-field and far-field seismic loads are compared and studied. The influence of hydrodynamic effect on the vibration characteristics and seismic response of rectangular and circular equivalent single-pier structures is analyzed. The semi-analytical Morison equation method is compared. The results show that with the increase of water depth, the natural vibration period of bridge piers is prolonged and compared with that in anhydrous environment. The dynamic water pressure makes the seismic response of pier structure change significantly, and the dynamic response of pier structure under near-field earthquake is obviously larger than that of far field. Therefore, attention should be paid to seismic design of deep water bridges near faults. (2) on the basis of dynamic response calculation of deep water pier under near and far field earthquake excitation, it acts on rectangle. The distribution law of hydrodynamic pressure and the characteristics of total hydrodynamic pressure of two kinds of circular piers with different cross-section are compared and analyzed, and compared with the railway in China. The calculation method of dynamic water pressure in highway code and Japanese code is tested. In general, the dynamic water pressure of deep water pier structure increases with the increase of water depth. The hydrodynamic pressure along the pier height is a parabolic distribution which increases first and then decreases. The total dynamic water pressure specified in Japanese code is higher than that in Chinese highway code. For the distributed hydrodynamic pressure, under near-field earthquake, for the rectangular section pier, the two specifications of the dynamic water pressure estimate is insufficient; For circular section pier, the Japanese code is conservative and the result of railway code is close. Under far field earthquake, the hydrodynamic pressure of the two kinds of code algorithms is conservative. The method of synthetic near-fault pulsed ground motion is used to quantitatively analyze the rectangular pulse parameters of pulse peak value, pulse period T _ p and pulse type. The effect of circular cross-section on the dynamic response of deep water bridge shows that under the action of synthetic near-field pulsed ground motion, the response of deep water pier structure is larger than that without pulse. And pulse peak Vp, pulse period Tp, pulse type. These three kinds of pulse parameters have a significant effect on the seismic response of deep water piers. The effect of peak pulse V _ p on the seismic response of deep water piers increases with the increase of VP. When the pulse period is close to the natural vibration period of pier structure, Tp has the greatest influence on the ground motion of deep water pier. In the range of the natural vibration period of deep water pier structure, the effect of C type pulse on the ground motion response of deep water pier is the biggest and the second is the B type and the second class A.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U442.55

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