Verification of Girder-Distribution Factors for Short-Span Steel Girder Bridges by Field Testing

Abstract

The procedure and results of field tests performed on five simplysupported, short-span steel girder bridges to verify girder-distribution factors (GDFs) are presented. Prior analytical studies have shown that, in most cases, currently used GDFs are too conservative. However, these studies also showed that, for short spans and short girder spacing, the GDFs can be too permissive. Therefore, this paper focuses on the experimental evaluation of girder-distribution factors for short-span steel girder bridges. The research work involved formulating the testing procedure, selecting the structures, installing the equipment, determining the measurements, and processing the results. Strains and deflections were measured and filtered to calculate GDFs. The results were compared with the distribution factors specified by the AASHTO Standard Specifications (1996) and the AASHTO LRFD Code (1998). The measured GDFs were found to be lower than the AASHTO values in all cases.