• Review Points
• Homework Observations
• Discussion of HW 13: Digital Bridge Project

The Structural Design Process

• Design is a process of model building.

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

  • In structural design for buildings, there are generally four identifiable levels in the development of the design description.

  • Levels of Design Description:

    1. Overall building spatial organization: the architectural concept.

    2. Overall structural organization: the structural concept.

    3. Approximate dimensions of major elements and subsystems with verification through approximate analysis and experience.

    4. Full design description with sufficient detail to produce and assemble all components.

  • A design phase involves moving from one level to another. The following phases are widely recognized.

  • Phases of Design Activity:

    • Conceptual Design

      • Moving from description level 1 to description level 2.

    • Preliminary Design

      • Moving from 2 to 3.

    • Final Design

      • Moving from 3 to 4.

  • A few points about each phase:

    • Conceptual design:

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

      • STRUCTURE DOESN'T SCALE.

      

      

      • The square-cubed law.

        • When an object is scaled up by a certain factor, the volume increases with the cube of the factor, while the cross section and surface areas increase with the square of the factor.

    • Preliminary design:
      • While conceptual design is highly creative and generative phase, preliminary design is more analytic and fault finding (i.e. searching for "concept killers").
        • Design requires successive cycles of creative generation and analytic criticism.

      • Preliminary design charts, such as those found in chapter 15 of Schodek, are very useful in establishing dimensions during preliminary design.

    • Final design:
      • Final design involves working the fine details:
        • 6 bolts vs. 8 bolts.
        • An 18-inch beam vs. a 16 inch beam.
        • etc.
      • The designer must prove that the structure is safe and serviceable under all reasonably possible load conditions the structure may encounter during its service lifetime.

    • All phases involve decisions that may involve have significant architectural and visual impact.

    • The tools used in the phases become increasingly sophisticated.

    • The descriptions become increasingly detailed.