【作者】 陈鲁；

【导师】 张其林；

【作者基本信息】 同济大学 ， 结构工程， 2007， 博士

【摘要】 悬索结构是最古老的结构形式之一。中国现代悬索结构之发展始于50年代后期和80年代。目前应用悬索结构的结构形式主要有悬挂体系、斜拉体系、张弦梁屋架、平面索桁架、单层索网、空间索网格以及张拉整体结构等。近几十年来,随着索结构被应用的越来越广泛,其设计计算理论也得到了很大的完善和发展。索是工程设施的重要结构构件,索力是索结构的一个重要参数,如何确定施工过程中和使用过程中结构的索张力大小就成为了摆在工程设计人员面前的一个重大问题。本文论述的弹性磁学EM(Elasto-magnetic EM)技术方法是测量预应力结构和拉索桥中索力的新方法。这种方法能够克服现有方法的缺点,是一种具有较好稳定性和较高精度的无损检测方法。弹性工程磁学法又称为磁通量法,由电磁感应现象,两个线圈组成一个电磁感应系统,主要线圈通入直流电,通电瞬时,由于有铁芯存在,会产生电磁感应现象,也就是说,会在次要线圈中产生瞬时电流,因此在次要线圈中会测得一个瞬时电压。此感应电压为瞬时,须通过放大器经由数据采集系统得到。电磁感应产生的电流强度以及电压的大小依赖于铁芯材料本身,或者说与铁芯材料的磁导率有着直接的关系。而且,铁芯材料的磁导率又与铁芯的应力状态相关,实际上我们可以通过该电磁感应系统测量得到的输出电压以及铁芯材料的其他的一些材料参数(例如横截面积,温度)等换算得到材料的磁导率。因而也就可以间接地得到铁芯材料的应力状态。首先,本文讨论了悬索结构和拉索结构的研究现状与发展前景,介绍了现行的各种对拉索张力进行测量的方法理论。其次,从基本理论着手,详细介绍了作为弹性工程磁学法理论基础的几个学科的基本理论内容。阐述了金属晶体学的基本理论,包括晶体的结构及其基本性质、金属的基本结构及其性质、晶体的结构缺陷以及金属晶体的能量理论等内容一一作了论述;详细叙述了电磁学的基本理论,介绍了铁磁性物质的磁化理论、磁化的微观机制、磁畴结构以及磁能等各个方面的内容。也阐述了索结构的力学计算理论,推导了单索的平衡方程、几何方程和变形协调方程,并简要介绍了钢索的材料性质和钢索锚具的相关内容。然后,本文讲述了弹性工程磁学法的基本原理与测量方法。形成了比较完整的测量原理与测量方法,并研制了基本的测量仪器,有了这些理论、方法以及设备,就可以进行试验工作了。接着,论述了一个针对弹性工程磁学法基本理论和测量方法的验证性的初步试验。分析了试验结果及结论,通过试验结果,可以得到,输出电压值对于不同拉力状态具有较好的灵敏度,因此应用弹性工程磁学法测量索拉力的方法的实用性也在试验中得到了证实。接下来又介绍了应用弹性工程磁学法进行实际工程测量的试验,包括安徽大学体育馆模型试验、中国航海博物馆模型试验以及广东省博物馆预应力钢索拉力检测。结果说明,弹性工程磁学法测量拉索拉力的方法是可行并且具有较高的精度的。最后,关于进一步工作的方向进行了简要的讨论。更多还原

【Abstract】 Cable structure is one of the oldest kind of structures. The modern cable structure in China developed on 1970s. Nowadays, analysis and calculation for this kind of structures had been to a very advanced level. However, cable is the importance part of structure, so theory and methods of checking and measuring the tension of cable should have been developed. The EM method introduced in this paper is a new kind of method to measure the cable’s tension. This method is also a lossless method which has high precision and stability.The EM is abstract of Elasto-magnetic. From Faraday’s theory, if there is a system which has two coins, te direct current is imported into the primary coil. According to Faraday’s law, at the same time, because there is cable in the center of this system, instantaneous current would be present in the second coil. So we can measure the instantaneous voltage. This voltage is depended on the magnetic permeability of cable. Therefore the magnetic permeability is also depended on the cable’s stress. So the tensile stress of cable can be known by measuring the instantaneous voltage of second coil.In this paper, some other methods are introduced one by one and advantage, shortcoming and applicable field of methods also are expressed here.As the basic theory of the EM method, several kinds of knowledge are introduced in this paper such as mental theory, electrical theory and structural theory. And the basic theory of EM theory is also discussed.An experiment which can test the EM theory is introduced. From the result of this experiment, we can validate the practicality of EM method. And we developed a measure system from this experiment.And then, several experiments that used the EM sensor to measure the true project is introduced. These experiments include the model of AnHui university stadium, the model of China sail museum and the GuangDong Museum. The result of this experiment expressed that EM method has high precisionIn the finality, the problems requiring further studies are discussed.更多还原