Abstract
In 1997, The American Society of Civil Engineers published a report prepared by their Task Committee on Avoiding Failures caused by Computer Misuse, the self-checking procedures developed in this research have been designed to prevent such misuse. In 2002, The Institution of Structural Engineers, published Guidelines for the use of computers for engineering calculations, which commence "These guidelines have been prepared in response to growing concern regarding the appropriate use of computers for structural calculations" and end with "Ten Top Tips to help get things right". The IStructE guidelines give definitive technical management advice which the writer advocates. This research deals with engineering matters not covered by the IStructE guidelines, the target audience is engineers who develop and support software for the production of engineering calculations. Verifying the correctness of structural engineering calculations considers calculations for both the structural analysis of frameworks and the structural design of components such as beams, slabs & columns, and develops a unified approach for the development of Verified Models for both types of calculation. In this thesis, verifying means establishing the truth or correctness of software models by examination or demonstration. Each model to be verified incorporates a self check, verification is the process of generating a thousand or more discrete sets of engineered data providing high coverage for the model, running the model with each set of data, computing the average percentage difference between key results produced by the model and its self check, averaging the key results for each run, averaging for all runs and when the average percentage difference for all runs is within an acceptable value, typically 3 % for models for structural analysis, then the model is said to be a verified model. Tools used for assisting verification are discussed including: benchmarking, flow charts, check lists and aids, help, generating sets of test data, self checking software, checking against known solutions, conversion of parametric files to numeric files, cross referencing of variables. Approximately 50% of calculations submitted to building control departments for approval are now produced by computer. Engineers say that due to the pressure of work in the design office, checking is not as thorough as they would like. From the starting position that the data has been checked, this research develops an extensive set of models which are self checking and have each been verified with sets of automatically generated data providing extensive coverage for each model. All systems are described in sufficient detail such that they may be used by others.