Vibration-Based Condition Assessment and Retrofitting of the Chambal Railway Bridge in India

In recent times, there has been a growing interest among researchers in vibration-based damage detection methodologies, given their attractive features and the potential to offer continuous health monitoring at a reasonable cost. This study focuses on assessing the extent of damage in a pier of the Chambal Bridge, situated on the Chambal River in the Bhind-Etawah section of the North Central Indian Railways. The investigation was prompted by the observation of visible cracks in the bridge pier, causing disruptions to regular passenger and goods train services. Conventional nondestructive tests were ineffective in gauging the extent of damage, leading to the necessity of vibration-based condition assessment. An ambient vibration test was conducted to extract the modal properties of undamaged and damaged piers. Changes in frequency were utilized to estimate stiffness loss, while differences in mode shapes were employed to pinpoint the locations of damage. The findings revealed significant stiffness degradation, prompting the development of a retrofitting plan. A detailed finite element analysis guided the design of a reinforced concrete jacket with additional reinforcements to restore the damaged pier’s original strength and stiffness, which eventually facilitated the safe resumption of train services.