【作者】 何伟；

【导师】 王博；

【作者基本信息】 郑州大学 ， 水工结构工程， 2010， 博士

【摘要】 中、下承式钢管混凝土拱桥是一种新兴的桥型,应用广泛。但近年来国内外出现了多起中、下承式钢管混凝土拱桥垮塌事故,造成了较大的人员伤亡和经济损失。据统计大多数事故产生的主要原因是吊杆的锚固失效或吊杆锈蚀断裂。由于桥梁的突发事故与其健康状态有关,因此若能对桥梁的损伤程度和健康状态进行识别与评估,多数事故是可以避免的。中、下承式钢管混凝土拱桥中比较容易发生且对结构安全造成隐患的损伤主要包括吊杆、横梁、系杆等构件的损伤,因此,吊杆、横梁、系杆等构件的损伤识别是中、下承式钢管混凝土拱桥损伤识别研究中的关键问题。本文针对中、下承式钢管混凝土拱桥损伤识别问题进行研究,取得的主要研究成果如下：1)针对横梁、系杆梁等梁类结构,提出了基于频率和振型摄动的结构损伤识别方法。在进行损伤识别时,先通过振型的变化分别建立损伤初定方程和损伤确定方程,运用振型摄动求解损伤单元位置和损伤程度,再运用频率摄动方程进行损伤校核,以确保损伤识别结果的唯一性和准确性,有效地避免“伪损伤”的出现。该方法可以利用频率测试精度较高而振型信息量丰富的优点,任意选取与可测自由度对应的方程构成损伤识别方程组进行求解,可提高计算效率和精度,识别结果可靠。分别采用数值模拟和钢梁试验说明了即使结构出现损伤程度较小的多单元损伤,只需一阶模态,即可完全识别出损伤,避免工程中高阶模态难测而无法识别损伤的情况。2)针对大型结构的测试信息不完备的情况,提出了广义残余力向量的概念和基于广义残余力向量法的结构损伤识别方法。通过测试结构前几阶低阶模态,计算残余力向量差矩阵,并取矩阵各行元素绝对值最大值构建广义残余力向量。损伤识别时先利用广义残余力向量初定可能损伤单元位置,再通过频率摄动对单元损伤程度进行筛选,确认损伤位置。分别以简支梁和桁架数值模拟及钢梁试验验证了该方法的可行性。3)针对吊杆的损伤识别问题,基于摄动理论分析了吊杆损伤对吊杆系张力和桥面位移的影响,提出采用吊杆张力或结点间位移差的变化来识别吊杆的损伤。通过算例验证了运用与损伤吊杆相邻吊杆张力的变化来识别吊杆损伤时,识别结果精度最高,各吊杆损伤识别结果精度随着与损伤吊杆距离的增加而降低。采用基于结点间竖向位移差的变化来识别吊杆损伤,方法实用,结果可靠。4)针对吊杆张力测试中存在的问题,建立了考虑弹性支承、附加质量等复杂边界条件下吊杆张力与横向振动频率之间的隐式关系式。该表达式精度较高,适用于各类吊杆。同时,为便于工程应用,给出了考虑简单边界条件的吊杆张力简化计算式。基于Rayleigh法给出了考虑弹性支承和附加质量等复杂边界条件的吊杆张力计算显式表达式,采用不同的振型函数给出了多种吊杆横向振动频率与吊杆张力之间的显示关系式。最后通过实例验证了各表达式的精度,分析了各表达式的应用特点与差异。5)根据中、下承式钢管混凝土拱桥的特点,说明了中、下承式钢管混凝土拱桥健康监测的流程,给出了桥梁健康档案指标的构成及特点。以郑州黄河二桥主桥为实例说明了中、下承式钢管混凝土拱桥健康状态评估的实现。更多还原

【Abstract】 Half through or through concrete filled steel tubular arch bridge (CFSTAB) is a newly-developing type bridge and widely applied. But in recent years there are many collapse accidents of half through or through CFSTAB both at home and abroad which have caused great casualties and economic losses. According to the statistics, the main cause of the accidents is anchorage failure or hanger corrosion fracture. Because the disasters are closely related to the health statu of the bridge, most of accidents could be avoided if the extent of damage and health status of the bridge can be assessed in time. The damage of this type bridge mostly occurred in beams, tie bars, suspenders and other components. So such damage detection is the key problem of damage identification for half through or through CFSTAB.In this paper, the crucial problems to solve in damage identification method for half through or through CFSTAB have been studied and some corresponding solutions have been put forward. Main research results of the thesis are as follows:1) For beams, tie bars damage identification a new method based on the perturbations of frequencies and mode shapes is proposed. First, according to the changes of mode shapes between damage and undamaged structure, damage pre-determination and determination equations are established. The perturbation of mode shapes are used to solve element damage parameters, then the detection results are substituted into damage check equations based on frequencies differences to check the precision of the results. The damage detection equations established from this method can guarantee the uniqueness of recognition results, avoid "pseudo damage" phenomenon. Numerical examples and the tests show that even the structure are multiple and low extent damaged, only one-order mode is need to identify the damage.2) For large-scale structure and the incomplete test information a concept of generalized residual force vector and a new method for structure damage detection based on generalized residual force vector are advanced. Firstly, the damage structure is measured to get the residual force vector matrix. Then the matrix is compared with the one of undamaged structure to get the difference matrix. The biggest absolute value in each row of the difference matrix formed the generalized residual force vector. In damage identification the improved residual force vector is defined to locate the suspected damaged elements preliminarily. Then the damaged extent is estimated by frequency perturbations. The numerical simulation and experiments prove the feasibility of the method.3) The influence has been analyzed to suspender tension and deck displacement caused by the damage in suspender based on the perturbation theory. And a new method of damage identification for suspender is advanced based on the change of suspender tension or displacement difference between nodes. And the examples show that when the tension difference of the adjacent suspenders to the damaged one was used to identify damage, the accuracy of the result is the highest. And the result precision is decreased with the distance increases between the suspenders and the damaged one. The method using the changes of vertical displacement difference between nodes to identify suspender damage is practical and reliable.4) For suspender tension test problems, the implicit expression between the vibration frequency and suspender tension is set up which has consider the influence of elastic support, additional quality and others complex boundary conditions. The expression is high precision and applicable to long and short suspenders, but the form is complex. So the simplified calculation formula has been studied with the normal boundary conditions. For convenience in engineering application the explicit expressions are proposed under the complex boundary conditions of elastic support, additional quality and others based on Rayleigh theory. And different vibration mode function is used to derive the relationships between the suspender tension and the vibration frequency. Finally, an example is used to verify the accuracy of the various expressions. And the application characteristics, differences of the expressions have been analyzed too.5) According to the characteristics of the half through or through CFSTAB the process of health monitoring has been illustrated, and the composition and characteristics of bridge health record indexes have been explained. Zhengzhou Yellow River Bridge is taken as an example to illustrate implementation of health assessment to through CFSTAB.更多还原