Strain-Based Condition Assessment of a Suspension Bridge Instrumented with Structural Health Monitoring System

Strain provides information about local behavior of structural components, and is one of the most concerned parameters in the structural health monitoring (SHM) of civil structures. It plays an important role in the condition assessment of bridges in terms of fatigue or yielding of the structural material, safety reserve or reliability of structural components, etc. The Wind And Structural Health Monitoring System (WASHMS) deployed on the suspension Tsing Ma Bridge (TMB) in Hong Kong has hitherto operated continuously for 17 years. As part of the WASHMS, 110 strain gauges were installed on the bridge to measure the dynamic strain response of the TMB. Based on the strain measurement data acquired in 2012, the structural condition of the TMB is evaluated by addressing the following issues: (1) Evaluation of the characteristics of stress responses in structural members on different deck cross-sections and comparison with the results obtained in 1999. (2) Statistical analysis of daily maximum stresses in different members and comparison with the design values (designated stresses) due to live loads at both serviceability limit state (SLS) and ultimate limit state (ULS). (3) Evaluation of the inner forces of monitored structural members and the corresponding strength utilization factors (SUFs). The assessment results obtained in the present study can be used as a reference or guideline for scheduling the bridge inspection and maintenance activities.