Load testing of highly skewed concrete bridges

Recurrent service problems and uncertainties in load distribution have been frequently reported by Departments of Transportation for skewed bridges. Service problems, such as deck cracking or excessive bridge racking can lead to bridge deterioration, and indicate the need of a better understanding of the structural response of high skew bridges to service loading. This paper presents the instrumentation and load testing of a three-span, medium span length, prestressed concrete bridge with 64° of skew to understand service, analysis and design problems associated with skew. The instrumentation plan for the bridge was developed based on service problems observed in concrete bridges with high skew such as deck cracking and displacements, as reported by the literature and by regular bridge inspections. Complete understanding of skew related responses required both short-term testing and long-term load monitoring. Structural responses of the key areas of the bridge to live and temperature loads and shrinkage were measured. The effects of certain bridge details on live load distribution were determined using finite element models validated through short-term load testing data. The evolution and magnitude of bearing movements and deck strains were captured for long periods of opposite thermal tendencies.