Comparative study of long-term displacement measurement methods − Focusing on a Pre-stressed concrete bridge under construction

Bridges continuously deflect over their entire lifetime, mostly due to fatigue, deterioration, time-varying material properties, or changes in boundary conditions. Long-term displacement can be employed in both the construction and operation stages for quality control and prognostic maintenance measures. Despite their versatile advantages, conventional sensors are limitedly employed for long-term displacement measurements owing to practical limitations such as clearance occupation, financial feasibility, long-term drift error, or insufficient displacement resolution. This study aims to demonstrate the long-term application of displacement measurement methods on a full-scale railway bridge using a dual-camera system, a light detection and ranging (LiDAR) system, a strain gauge, a linear variable differential transformer (LVDT), and a ring gauge for long-term monitoring for 548 days. The resulting displacements are comparatively analyzed based on dead loads and weather conditions, elucidating the practical issues arising in the long-term displacement monitoring of full-scale bridge.