【作者】 贾玲玲；

【导师】 柳春光；

【作者基本信息】 大连理工大学 ， 防灾减灾及防护工程， 2009， 博士

【摘要】 跨河、跨江桥梁结构以及海洋平台的动冰力研究已逐渐成为寒冷区域结构工程抗冰反应分析的重要任务之一;其中桥梁结构作为跨海、跨河流域的重要交通枢纽,在冰激作用下的振动研究更是不容忽视,显得尤为重要。考虑到进行室内模型试验可以方便地控制一些参数,同时可以将各项参数进行合理组合,以便能够直观和更深入地发现在原型观测和现场试验中出现的问题,也便于找出各参数之间的内在联系,总结出一般规律,为寒冷海域和江河流域的结构抗冰设计提供重要的参考价值。鉴于此,本文针对冰激桥墩结构振动问题从不同方面展开了一系列与之相关的研究,主要研究内容如下:(1)根据结构抗震反应分析思想提出了冰振反应谱,首先建立了基于功率谱密度函数的冰振反应谱;其次借鉴地震反应谱内插法的思想从理论和实际观点出发,假定在等距离微小时间间隔内冰荷载按二次抛物线规律变化,由Duhamel积分推导出冰振位移、速度以及加速度反应谱的一系列连锁公式,建立了基于非线性内插法的冰振反应谱,并利用实际冰压力时程曲线进行了冰振反应谱数值分析,为以后冰激结构振动的研究提供一种方便、简捷、精确的分析方法,也能够将其有效地应用到结构的抗冰计算中。(2)考虑到室内模型设计的难易程度直接关系到模型试验能否顺利进行,本文在两个合理假定的基础上,根据相似基本理论及强迫振动理论,推导出一种改进的动冰力模型试验相似律,以便能用更精确的模型试验结果去预测原型结构在冰荷载作用下可能发生的破坏。同时为验证该相似律的合理性及适用性,通过冰激桥墩振动算例进行了数值分析,分别对频率、时间、位移、速度以及加速度等相似比尺进行了理论验证。(3)为有效地解决荷载输入信息已知和部分输入信息未知情况下,结构的物理参数识别问题,探求了一种改进的物理参数时域识别和荷载反演算法,并利用该算法对一悬臂型桥墩结构的多个参数识别结果进行了有效验证。此外,考虑到精细时程积分法的方便适用性,首次将其应用到动冰荷载的识别中;并通过具体算例和真实试验数据对以上两种算法的识别效果分别进行比较分析,进一步深入说明其在实际工程计算中的适用性。(4)利用本文提出的改进的动冰力模型试验相似律设计了一桥墩模型,首次在大连理工大学海岸和近海工程国家重点实验室,开展了冰激柱体桥墩振动室内模型试验。通过本试验,分析直立桥墩结构在冰振作用下的响应特点,并探讨冰的破坏形式以及冰压力时程曲线的特性;同时将有限元计算结果和模型试验结果结合起来进行分析比较,进一步验证本文提出的改进的动冰力模型试验相似律的适用性。(5)基于考虑流固耦合效应的桥墩振动响应分析方法,在流体理论分析基础上,建立了不同环境荷载激励下的非线性Morision方程,并利用Matlab数值分析软件对不同工况下的墩-水耦合振动响应进行了计算比较。由于该方程同时考虑到附加质量效应和流固耦合效应,能够真正解决结构与水的耦合振动问题,有利于深水桥墩结构设计。更多还原

【Abstract】 Researches on dynamic ice forces acting on bridge structures over rivers or seas and ocean platforms is one of the important tasks of the ice-resistance response analysis in cold areas.The vibration analysis of bridge structure as the traffic keys over sea and river need to be carefully and is of paramount importance.Considering almost all the parameters can also be controlled conviniently and united reasonably in the model test,performing model test in laboratory is an effective way to find the problems directly in prototype measurement and field experiment,to analyze the relations between each parameter,and to generalize the general laws.All of the above can provide important references for the ice-resistance design in cold areas.Therefore,a series studies of ice-pier vibration are performed from different aspects in this paper.The main work of this his thesis is summarized as follows:(1) Ice response spectra is proposed based on the idea of a seismic response spectra analysis of structures.Firstly,ice response spectra on the basis of power spectra density function is established;Secondly,based on the assumption of quadratic parabolic interpolation method,the nonlinear interpolation analysis method of ice response spectra is studied from both theoretical and practical points of view,and the successive computation formulas including ice displacement,velocity and acceleration response spectrum are deduced by Duhamel integral.Furthermore,to analyze the effectivity and applicability of the method, the real temporal curves of ice pressure are used to be studied.The results show that the presented method is more convenient and accurate to study the structural response induced by ice force,also it can be effectively applied in the design of ice resistance.(2) The degree of accuracy extent of model design directly relates to the success or not of model test.In this paper,to study similitude laws for dynamic ice force model test which is always a hot problem in ice mechanics,a new modified similitude law for dynamic ice force model test is proposed based on ice-induced virbration theory and two reasonable assumptions.So that more precise results of model test can be obtained to evaluate the possible damage of the prototype structure excited by ice loads.To verify the validity and applicability of the similitude law,a ice-induced pier vibration is examplified,and the similitude ratio of time,displacement,velocity and acceleration are analysized in theory, respectively. (3) To solve the parameter identification problem of the flexible arm structure with known loads information or other incomplete input information,an improved physical parameter and load inversion method in time domain is proposed in this paper.A flexible arm pier structure with unknown imput,as the numerical example,is given to verify the new algorithm.Furthermore,precise time integration method is introduced to identify dynamic ice loads due to its facility and applicability.Then,a numerical example and real test datas are performed to investigate the identification effect.The results show that both the first algorithm and the precise time integration method can be effectively applied to identify dynamic ice loads in practical engineering.(4) Based on the modified similitude law,a laboratory test is performed for the simulation of ice-induced vibrations of a pier structure in state key laboratory of coastal and offshore engineering,dalian university of technology.In the model test,the response characteristic of pier structure introduced by ice loads is analysized,and the damage form is also studied.Furthermore,the results obtained from model test and FEM numerical calculation are compared.So that the improved similitude law for dynamic ice force model test also can be got to vertified both in theory and practice in further.(5) To consider the fluid-structure coupling effect on the response of bridge piers in deep water,on the basis of fluid mechanics principle,nonlinear Morison equation of the pier structure is established under different loads action.By the numeric analysis,the pier-water coupling vibration responses of bridge pier are studied and compared deeply under earthquake, ice loads and wave force action.As the effect of added mass of water and the coupling effect of fluid-structure are both considered in the nonlinear Morison equation applied in this paper, the probem of piers-water coupling vibration can be settled fundamentally,and it is feasible to the piers design.更多还原