Final Scope

The design of bridges often involves the use of structural analysis models of varying degrees of complexity. Superstructure design models vary from approximate 1-dimensional line girder analysis models to complex 2- and 3-dimensional finite element analysis models. Substructure and foundation models often consider soil-structure interaction, second-order effects, dynamic response (for seismic analysis), and interaction with the superstructure. A variety of software analysis programs are used to create and run these models, both commercial software and user- developed software. These models, and the structures they represent, can be quite complex, with enormous amounts of input parameters and output of results.

Structural analysis typically includes choosing appropriate software, identifying qualified staff, creating appropriately refined models, making appropriate assumptions, performing the analysis, and checking the results. The quality process is even more rigorous for complex structures.  The engineer must understand the limitations of the software, the anticipated behavior of the structure, and review the predicted behavior of the models to determine if the model is correctly representing and estimating the real-world performance of the structure. A simple “check the program input values” is not always practical, or sufficient, for checking these models. Often it is necessary to perform other actions to check the model, such as “sanity check” reviews of key model results, comparing the model results to the results of simpler analysis methods, performing full independent analysis modeling and comparing the results, or other methods.

The objective of this synthesis is to document state department of transportation (DOT) practices related to the quality processes for bridge analysis. The synthesis will document the processes used to identify appropriately qualified staff, choose appropriate software, model the structure, and validate the results.

Information to be gathered includes (but is not limited to):

• Identification of DOTs that have formal and informal quality processes for models and those that do not.
• Written or informal processes for identifying appropriately qualified staff, both in-house and consultants (e.g., education requirements, license requirements, experience levels, prequalification requirements);
• Written or informal processes for choosing appropriate software (e.g., prequalification lists, required type of analysis for a given structure type or for a given purpose of analysis);
• Written or informal processes for modeling the structure (e.g., boundary conditions, material properties, loading distribution, section loss, nonlinear versus linear, dynamic, time dependent, buckling, type of element, soil structure interaction);
• Written or informal processes for validating the results (e.g., line-by-line checking, “sanity check” reviews of key model results, comparing the model results to other results, independent review and analysis, instrumentation); and
• Written or informal processes for reconciling discrepancies between independent models.

Information will be gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected agencies for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial):

• Adams, A., et al., “Manual for Refined Analysis in Bridge Design and Evaluation,” Report FHWA-HIF-18-046, Federal Highway Administration, Washington, DC, May 2019.
• Choe, L, et al., “Evaluation of Prestressed Concrete I-Girder Bridge Design Software with NCHRP Process 12-50,” Transportation Research Record Number 2131, (Structures), Washington, DC, 2009.
• Jungil, S., et al., “Evaluation of Composite Steel I-Girder Bridge Design Software Using NCHRP Process 12-50,” 89th Annual Meeting of the Transportation Research Board, Washington, DC, 2010.
• Michael Baker Jr. Inc., et al., “Bridge Software Validation Guidelines and Examples,” NCHRP Report 485, Transportation Research Board, Washington, DC, 2003.
• Mlynarski, M., et al., “A Comparison of AASHTO Bridge Load Rating Methods,” NCHRP Report 700, Transportation Research Board, Washington, DC, 2011.
• Mlynarski, M., et al., “Bridge Software Validation Guidelines and Examples,” Transpor- tation Research Record Number 1696, Washington, DC, 2000.
• US Nuclear Regulatory Commission, “Software Quality Assurance Program and Guide- lines,” Report NUREG BR-0167, Division of Information Support Services, Office of In- formation Resources Management, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, February 1993.
• Varma, A.H., and Jungil, S., “Verification of LRFD Bridge Design and Analysis Software for INDOT,” Report FHWA/IN/JTRP-2009/27, Joint Transportation Research Program