Role of Skew on Bridge Performance

Abstract

Gravity load paths of high-skew bridges differ from the ones with no skew. High skew can also lead to stresses or displacements that adversely affect service performance. This paper demonstrates the effects of skew on bridges through finite element analyses, bridge inspections, and statistical analyses. Five deck-girder type bridges with and without skew were inspected. A database of more than 1,400 deck-girder type bridges was analyzed to seek relationships between skew and National Bridge Inventory (NBI) ratings. Practices of Departments of Transportation (DOT) were compared with each other and to provisions of AASHTO LRFD Bridge Design Specifications (BDS). Acute deck corner cracking and bridge movements were documented on some high-skew bridges. Field inspections and database analyses showed that not all high-skew bridges have performance issues, and NBI ratings are in general not sensitive to skew. This is likely because of many factors affecting performance and certain details mitigating skew effects.