Abstract Manager

Bridges are key components of public transportation networks. Bridge owners need to ensure that proper maintenance programs are executed to maximize the lifespan of their assets safely, while ensuring that fiscal year expenditures are managed efficiently. Detailed structural evaluations are typically performed as bridges approach the end of their design service life. The assessment of bridge bearings (which support the superstructure and accommodate thermal movements) is a critical component of such structural evaluations. Bearing replacements are costly, as the work often requires construction of temporary load-bearing structures to jack and support the superstructure during bearing replacement. The topic of this study pertains to a 57-year-old concrete bridge located in Florenceville NB, which is undergoing a multi-year condition assessment and rehabilitation program. One component of the condition assessment, and the focus of this article, involves the assessment of main-span bearings. To complement traditional visual inspections, six vibrating wire deformation gauges were installed to monitor longitudinal displacement of the superstructure and temperature over time using an autonomous data acquisition system. The experimental results from 367 days of monitoring have shown that: 1) observed peak deformations during seasonal temperature changes are found to be in reasonably good agreement with computed theoretical movements, 2) instrumented bearings have returned to near their initial position after one complete calendar year, and 3) the coefficient of thermal expansion of the main span superstructure is shown to be in good agreement with the general design values recommended in the Canadian Highway Bridge Design Code. Based on the results of this detailed assessment, it was determined that the replacement of main span bearings is not warranted at this time, and such outcome has led to significant cost savings for rehabilitation of this structure.