Structural Systems: Design Conception and Scale
Review points from lecture 25


Arch 324/624, Introduction to Structural Design, University of Virginia Copyright © 1996-2009 Kirk Martini. Last Modified Wed, 07-Jan-2009 8:35

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• Design is a process of model building.

  • Building a series of descriptions that are increasingly more detailed.

  • Structural Design can be viewed in terms of three general phases

    • Conceptual Design

      • Developing the overall organization of the structural system.

    • Preliminary Design

      • Developing approximate dimensions and organization of major subsystems and elements.

    • Final Design

      • Determining precise dimensions and configuration of all elements and connections.

• As things become larger, structure becomes an increasingly important determinate of form.

  • Because of the square-cubed law, Structure doesn't scale.
    • The square-cubed law: Area increases with the square of the scale factor, volume increases with the cube.

  • When a model is geometrically scaled by a factor K:

    • Stresses increase by K.

    • Deflections increase by K².

  • For any model, there is a scaling factor K that will cause it to collapse under its own weight.

  • Things that are possible and reasonable at a small scale may be impossible and unreasonable at a large scale.

  • Working with small scale models is very valuable, but can be misleading.

Arch 324/624, Introduction to Structural Design, University of Virginia Copyright © 1996-2009 Kirk Martini. Last Modified Wed, 07-Jan-2009 8:35

Table of Contents