Indirect Monitoring of Railway Bridges by Direct Integration

Railway bridges are of importance as critical elements in transportation networks. Unfortunately, many railway bridges are old and these structures are subject to degradation over time. To monitor bridge structures, many methods are introduced. In recent years, indirect bridge monitoring methods have become more popular. These methods use passing vehicles to measure dynamic responses such as accelerations. In this paper, a new direct integration approach is introduced to directly calculate the apparent railway track profile (AP) that is consistent with the measured accelerations. An adaptation of the Newmark Beta numerical method is used for this purpose. Using AP, bridge displacement profile difference (BDPD) is calculated to monitor bridges. The BDPD is the difference between the baseline (healthy) profile and the apparent profile after damage and environmental effects. BDPD is sensitive to temperature change and bridge damage. It has its own frequency which is close to the bridge frequency.