Field testing of multiple span railroad flatcar bridges on low volume roads

摘要

The use of railroad flatcar (RRFC) bridges on low-volume roads was investigated in research conducted by the Bridge Engineering Center at Iowa State University. Previous research has demonstrated the feasibility, constructability, adequacy, and economy of using RRFC bridges, especially for use as single span bridges in which the spans are shorter than 66-ft in length. To verify the adequacy of using RRFC bridges for multiple spans, three multiple span RRFC bridges were field tested; two two-span bridges located in Buchanan County, Iowa and one three-span bridge located in Winnebago County, Iowa. A preliminary investigation into the use of sheet pile abutment was also made in conjunction with the testing of the Winnebago County RRFC bridge. All three bridges tested exhibited responses that were within the guidelines for bridge behavior (strains and deflections) as determined by the 1998 AASHTO Bridge Design Standard Specification. Transverse live load distribution characteristics were determined by grillage analysis and verified by live load deflection data from field tests. A simplified design procedure was developed for multiple span RRFC bridges to assist in the design of future multiple span bridges. A rating procedure previously developed for single span RRFC bridges was expanded to include multiple span RRFC as well Based on the results of this investigation, through proper RRFC selection, engineering, and construction, single span as well as multiple span RRFC bridges can provide an economical and efficient replacement bridge system for low volume roads.