Damage Character Analysis Of Self-anchored Suspension Bridges And Damage Identification Of The Main Girder

Entering the21st century, transportation infrastructure facilities increase continuously, with the high-speed development of China economy, which makes many large bridges have been applied widely. These bridges are not only as representative building, but also as transit hubs where they placed in. So it is an important work to ensure the safe and normal operating of the bridges during their existence,and bridge healthy monitoring is taken more seriously to know operation of using bridges more comprehensively, as whose important part the damage detection technique becomes the focus of research in recent years.Based on different theorys, there are many kinds of damage detection methods, having different detection effect on different parts of a structure, at present. Therefore it is nessary to research applicability of detection methods of structural members to monitor structural damage more availably.Considering above exposition, the paper, on the basis of finite element analysis and load test, analyses nondestructive bearing force characteristic and damage characteristic of Yang Mingtan bridge in detail,and in accordance with the above result, a variety of detection methods, of which most is based on dynamic analysis, is used for the primary beam being the most damaged part of the bridge.Then their detection effect is compared by which the paper finds a way being applicable to primary beam monitoring. The specific studies in this paper are listed as following:1. After reviewing related literatures, the paper presents a panorama of bridge healthy monitoring and gives a brief introduction of the development of damage detection technique both in China and abroad and important detection methods at present.2. The fundamentals of damage detection technique based on both statical and dynamic analysis are expounded systematically, and the main theorys of several detection methods used in the paper are also introducted.3. According to separable pendant line theory, finite element model of equilibrium state of Yang Mingtan bridge is established, by which statical and dynamic analysis of the bridge is done,and the analysis results are compared with the experiment value of the load test. Then it is known that the calculated value is close to the actual valuethe, indicating that the model is accurate and its analysis results has confidence.4. The damage of the primary beam, the pylon tower and the suspenders are simulated in the model.Then the statical and dynamic damage characters of the bridge, basing on undamage analyses.are searched,of which results show that the internal force of structure caused by the same statical and dynamic loads and natural characteristics of dynamic will changes.But the variation of medium damage of20%is not as obvious as that of the damage of the whole structural member.5.There are five damage parts simulated in the primary beam chosen according their mechanical characteristics and relationship with position of sensors.Each one has damage degree of10%,20%and40%respectively.Then basing on the identification effect and rate of the separate and modula damages of five parts, the curvature mode indicator CMSE of4th step vibration modes is made the main monitoring method, from used a variety of detection indicators, of the primary beam of Yang Mingtan bridge, which having both identification capacity of each simulation damage and good filter performance.