A Simple Monitoring System for Damaged Bridges in Myanmar

Abstract

Myanmar officials have observed damage and unwanted movement of some bridge structures situated within the Yangon, Myanmar region. Low bearing capacity soils (termed “soft soil” herein) may be responsible for the observed damage and unwanted movement. The observations may indicate that the current bridges have not been adequately designed and constructed to fully accommodate the soft soils. Several damaged bridges were repaired; however, it was not clear if these repairs halted the unwanted movement of the structures. We conducted comprehensive observations of the existing conditions to fully understand the contributing factors of the damage and unwanted movements. We utilized our detailed observations to develop a simple and straightforward independent monitoring system to assess whether the bridge repairs were successful in arresting further unwanted movement. The Thakhut Bridge and Twantay Bridge were selected as the subjects of our study. A monitoring system consisting of two displacement transducers and a portable data logger were installed on the Thakhut Bridge to monitor movement of the central pier. The monitoring results indicated that the central pier of the Thakhut Bridge moved 3.5 mm over an eight month period along the direction aligned with the bridge axis. Because the movement of the central pier in Thakhut Bridge behaves linearly with time, the future relative displacement can be predicted to be on the order of 5–6 mm per year. A monitoring system consisting of an inclinometer and a portable data logger were installed on the Twantay Bridge to monitor the inclination of the south main tower. Our observations indicated that the inclination of the south main tower of the Twantay Bridge ranged from 0.00° to 0.04° (in the direction of the bridge axis). The very small angles of inclination that were observed led us to conclude that the south main tower was in a stable condition. The implementation of a simple and straightforward independent monitoring system will permit Myanmar officials to effectively plan and implement the requisite maintenance and corrective measures for damaged bridges.