Bridge Software Validation Guidelines and Examples

NCHRP 12-50 is a research project to investigate current software validation procedures and to provide an improved method of verifying bridge design and analysis software. The removal of errors in bridge design and analysis software has a far-reaching impact on safety assurance in the design and rating of bridges. Bridge engineers are relying on automated computations at an increasing rate. Automation of bridge computations is now an integral part of routine practice. In theory, this software should be error free—yet perfect software remains elusive. The number of bridge types and geometric configurations, materials, and loadings creates a large solution domain that must be addressed. The validation method currently being developed involves the automated generation of a series of test suites. Each test suite will contain input files for several analysis engines (software packages) and the results of the analyses and designs performed by these engines. The automatic generation of input files for a particular software package enables thousands of different cases to be created in a matter of minutes. Similarly, the output from the engines can be compared automatically using database or spreadsheet software. Each problem generated will have slightly varying input parmeters. The goal is to increment the various input parameters to test as many articles of the LRFD Specifications as possible. This novel, systematic, and automated approach provides guidelines that can be applied to a host of computational processes associated with bridge engineering, specification development, and software maintenance. Some examples are presented to illustrate the process.