Performance of a skewed semi-integral bridge

This project was developed to enhance the Virginia Department of Transportation's (VDOT) in-house expertise in the design of integral bridges and to provide a resource for consultants performing design work for VDOT. It involved extensive field monitoring of a highly skewed semi-integral (integral backwall) structure. The main purpose was to provide feedback regarding some of the assumptions behind the recently adopted set of integral bridge design guidelines, ultimately leading to reduced construction and maintenance expenses for VDOT. The project was focused on the long-term monitoring of a skewed semi-integral bridge located on Route 18 over Blue Springs Run in Alleghany County, Virginia. This report presents the results and analysis of field data acquired from various sensors between October 19, 2006 (shortly after the bridge was completed), and March 24, 2008. The results to date indicate satisfactory field performance, with a need for further monitoring. The main reason for constructing jointless bridges is to eliminate recurring maintenance costs associated with deteriorated bearings and spalled beam ends, commonly encountered with conventional structures. It is estimated that these maintenance expenses amount to approximately $366,000 per year in Virginia. In the past 7 years, integral bridges constituted between 10% and 30% of the total bridges constructed by VDOT, with 24% reached in 2007. VDOT is committed to the design of jointless bridges where practicable, within a clearly defined set of constraints based on the current state of the practice. It may be possible to consider a greater percentage of bridges for integral design through a better understanding of the field behavior.