NCHRP Process 12-50 was implemented to evaluate and verify composite steel I-girder bridge design software used commonly in Indiana. A test-bed of twenty one bridges was developed with the guidance from an Indiana Department of Transportation appointed research advisory panel (RAP). The test-bed included five simple-span and sixteen multi-span bridge superstructures. More than 80 parameters were required to define a bridge and they include bridge span, girder spacing, number of beams, section type, steel strength, girder sections, and other required bridge parameters. Some of these parameters were initially selected by INDOT and practitioners.

An indigenous computer program PURDUE CSBD was developed to implement the bridge design calculations specified in the AASHTO LRFD specifications, which is currently endorsed by the INDOT bridge design manual. Both MERLINDASH and PURDUE CSBD were used to generate design calculation results for the complete test-bed of bridges. The output from both computer programs is compared to identify assumptions and discrepancies between MERLIN-DASH and the AASHTO LRFD specifications. These comparisons indicate excellent agreement between the results from both programs for: (1) moments, (2) shears, (3) stresses, (4) deflections, (5) flexural strength and all relevant parameters, (6) shear strength and all relevant parameters, and (7) shear connector related parameters. The test-bed of bridge structures and the PURDUE CSBD program are recommended for evaluating and verifying other bridge design software

Report Number



Process 12-50, composite steel, bridges, design, validation, test-bed, SPR-3023

SPR Number


Project Number


File Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, Indiana

Date of this Version