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PROCEEDINGS OF THE THIRD INTERNATIONAL CONFERENCE ON CIVIL AND STRUCTURAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
Simplified Structural Software using the Release-Deformation Method
Consulting Engineer, Dublin, Eire
R. Holloway, "Simplified Structural Software using the Release-Deformation Method", in B.H.V. Topping, (Editor), "Proceedings of the Third International Conference on Civil and Structural Engineering Computing", Civil-Comp Press, Edinburgh, UK, pp 199-206, 1987. doi:10.4203/ccp.4.8.4
The paper contains a plea for simplification and standardisation of structural software. This is particularly desirable since engineers do not normally have special expertise in programming. An engineer's training is unlikely to equip him with mastery of more than one programming language, for instance - formerly FORTRAN but now more likely to be BASIC. On the principle that an engineer should fully understand what ever method of analysis he uses, we might conclude that computer programs for general usage should be written in BASIC without the use of machine code programing. This, in effect, would preclude the use of graphics. This may not be such a serious drawback since most graphical displays are of limited practical value. The diagrams cannot be measured accurately or recorded by conventional printers; graphical programs are machine-dependent, lengthy and can require a lot of memory. Inclusive of data preparation time, diagrams can be slower to produce than sketches on paper. Although graphical displays rate highly as 'selling points' in commercial software packages, their real value may lie in identifying gross errors in output and thus acting as a check on the main program.
Comprehensive software packages can be criticised also in that they induce a false sense of security and accuracy, are unduly elaborate for straightforward design problems and are often difficult for the engineer to comprehend. The Author advocates standardisation of BASIC and disk formatting procedures and the use of non-graphical programs in elementary BASIC for everyday design work. This would allow portability of software from one computer to another.
A means of helping to achieve this is described in Part 2 of the paper. This outlines the Release-deformation method of analysis based on the Flexibility method of linear structural analysis. This involves the introduction of notional releases into the structure, identification of the resulting discontinuities and the application of forces to eliminate these and restore the structure to its pre-release status. These effects provide a set of equations that can be expressed in compact tabular matrix form using stiffness parameters. A Deformation diagram, used t o exhibit the behaviour of the loaded structure at release, is an important feature in sign determination. The tabulated figures are fed in sequence as data into an appropriate computer program. A suite of about seven programs of the type listed in the book 'Structural Design with the Microcomputer' is deemed adequate for solving nearly all common problems in practical structural analysis.
Based on these modular programs, a general classification system for structural software is recommended. This would identify the scope of a particular program and form a first step towards standardisation of structural software.
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