基于模态曲率的结构损伤检测技术研究.doc

毕业论文


2012 年 5 月
摘要
随着我国交通事业的迅速发展,桥梁、公路网密度不断提高,大跨度桥梁不断涌现。但是很多桥梁在使用过程中由于各种原因均可能发生不同程度的损伤、开裂或老化,从而埋下安全隐患,若不及时发现并修补就有可能造成重大事故,危害人们群众生命安全并导致重大的财产损失。因此,对现役桥梁结构进行损伤检测和早期预报,及时获取桥梁运营下的健康状况具有很重要的意义。
本文以模态曲率为基础,分析了其对于桥梁结构损伤评估的适应能力,并运用模态曲率差的变化率来确定损伤位置。模型实验表明模态曲率差的变化率不仅反映了桥梁损伤的位置,而且某些阶振型的模态曲率差还指示了损伤单元的长度,但在振型的平衡位置,模态曲率差不容易反映结构的损伤。实际检测中需要获得结构的多阶振型才可以对损伤位置实现较好的识别。
通过有限元分析表明,曲率模态对桥梁结构的整体损伤、局部损伤都有较好的敏感性,所得结论可为实际公路桥梁的损伤诊断提供参考。
关键词:ANSYS模拟;模态参数;损伤分析;模态曲率差变化率;桥梁结构
Title:Based on the modal curvature of the structural damage detection research
Abstract
With the rapid development munication industry in our country, density of work improves constantly and the large span bridge is emerging constantly. But structural damages such as cracking and aging etc. to some degree during the bridge structures service life occur from time to time, Some invisible damages do not alert the engineers in time and may result in disastrous consequences and ultimately cause substantial loss of life and property .Therefore, it is important mand the health status of bridge monly using state in time and to detect damages at the earliest possible stage.
In this paper. Modal curvature analysis of its ability to adapt to bridge structural damage assessment, and use of the absolute value of modal curvature to determine the damage location. Model experiments show that the absolute value of the modal curvature difference rate reflects not only the bridge damage position, but some of the vibration modes, modal curvature difference also directed the unit length of injury, but the modal curvature difference in the shapes of the equilibrium position, is not easy to reflect structural damage. Actual testing required to obtain the structure of multi-vibration modes the type can only be better identification of damage location.
Finite element analysis shows that curvature mode is a sensitive index in damage diagnosis for whole bridge structure or for pant of it. Some useful conclusions for girder bridge is