STRUCTURAL HEALTH MONITORING OF BRIDGES

Abstract

It is important to monitor the Structural Health of Rail and Road Bridges at suitable intervals. Visual inspection and usual hammer test can not reveal the internal faults, specially the incipient faults. The present work aims at identifying the parameters which need to be scientifically measured for evaluating Structural Health of Bridges and designing the instrumentation system for their measurement. Distributed Data Acquisition Systems has been used to cater to the needs of long Bridges. In this dissertation, important performance parameters like Strain and Vibration as. well as influencing parameters like Temperature Profile, Wind Speed and Speed of Vehicle running on the bridge are considered for monitoring bridge structure. For the measurement of these parameters various Transducers/Sensors are used, which are connected to Remote Data Acquisition Modules (RDAMs) through signal conditioning units wherever necessary. These RDAMs are networked to Central computer through RS-485 link for data acquisition. Data is collected by RDAMs from transducers as and when the central computer requests for data. Data acquisition software is written using C-language. The data so collected is stored in specified format in data files. In another exercise, Temperature gradient has been measured across the section of a beam by using RDAMs. Apart from these parameters, the measurement of parameters such as Length Change, Vertical Deflection, Inclination, Cracks and Prestressing Forces which influence the performance of Bridges has been discussed. Now--a-days, due to advancement in Optical Fibre technology, it is possible to use Optical Fibres for sensing purpose also. Hence instead of using Conventional Sensor system, Optical Fibre Sensor system is used for bridge monitoring with several advantages. In this disseration, various types of Fibre Optic Sensors are discussed and the application of those sensors in monitoring bridge parameters is proposed