土木工程专业英语带翻译Word格式文档下载.docx

1、practice. For example, because bridges, as well as most civil engineering structures, are large in size, and have quite lownatural frequencies and vibration levels, at low amplitudes, the dynamic responses of bridge structure are substantially affected by the nonstructural components, unforeseen env

2、ironmental conditions, and changes in these components can easily to be confused with structural damage.All these give the damage assessment of complex structures such as bridges a still challenging task for bridge engineers. This paper firstly presents the definition of structural healthmonitoring

3、system and its components. Then, the focus of the discussion is placed on the following sections:the laboratory and field testing research on the damage assessment;analytical developments of damage detectionmethods, including （a） signature analysis and pattern recognition approaches, （b） model updat

4、ing and system identification approaches, （c） neural networks approaches; andsensors and their optimum placements. The predominance and shortcomings of each method are compared and analyzed. Recent examples of implementation of structural health monitoring and damage identification are summarized in

5、 this paper. The key problem of bridge healthmonitoring is damage automatic detection and diagnosis, and it is the most difficult problem. Lastly, research and development needs are addressed. 1 Introduction Due to a wide variety of unforeseen conditions and circumstance, it will never be possible o

6、r practical to design and build a structure that has a zero percent probability of failure. Structural aging, environmental conditions, and reuse are examples of circumstances that could affect the reliability and the life 专业资料word of a structure. There are needs of periodic inspections to detect de

7、terioration resulting from normal operation and environmental attack or inspections following extreme events, such as strong-motion earthquakes or hurricanes. To quantify these system performance measures requires some means to monitor and evaluate the integrity of civil structureswhile in service.

8、Since the Aloha Boeing 737 accident that occurred on April 28, 1988, such interest has fostered research in the areas of structural health monitoring and non-destructive damage detection in recent years. According to Housner, et al. （1997）, structural healthmonitoring is defined as“the use ofin-situ

9、,non-destructive sensing and analysis of structural characteristics, including the structural response, for detecting changes that may indicate damage or degradation”1. This definition also identifies the weakness. While researchers have attempted the integration of NDEwith healthmonitoring, the foc

10、us has been on data collection, not evaluation. What is needed is an efficient method to collect data from a structure in-service and process the data to evaluate key performance measures, such as serviceability, reliability, and durability. So, the definition byHousner, et al.（1997）should be modifi

11、ed and the structural health monitoring may be defined as“the use ofin-situ,nondestructive sensing and analysis of structural characteristics, including the structural response, for the purpose of identifying if damage has occurred, determining the location of damage, estimatingthe severityof damage

12、 and evaluatingthe consequences of damage on the structures”（Fig.1）. In general, a structural health monitoring system has the potential to provide both damage detection and condition assessment of a structure. Assessing the structural conditionwithout removingthe individual structural components is

13、 known as nondestructive evaluation （NDE） or nondestructive inspection. NDE techniques include those involving acoustics, dye penetrating,eddy current, emission spectroscopy, fiber-optic sensors, fiber-scope, hardness testing, isotope, leak testing, optics, magnetic particles, magnetic perturbation,

14、 X-ray, noise measurements, pattern recognition, pulse-echo, ra-diography, and visual inspection, etc. Mostof these techniques have been used successfullyto detect location of certain elements, cracks orweld defects, corrosion/erosion, and so on. The FederalHighwayAdministration（FHWA, USA）was sponso

15、ring a large program of research and development in new technologies for the nondestructive evaluation of highway bridges. One of the two main objectives of the program is to develop newtools and techniques to solve specific problems. The other is to develop technologies for the quantitative assessment of the condition of