Code vs. PBEE


Potential misunderstandings under the Code, and how PBEE can mitigate them

  1. Buildings status after a major earthquake

    • Misunderstanding: Buildings designed “to Code” will definitely be undamaged and operational after a major earthquake

    • Truth: Such buildings can still be significantly damaged after a major earthquake

    • Limitation: Code only assumes a level of performance of life safety for a typical building at one design earthquake, but does not explicitly design to achieve that performance

    • Solution: PBEE permits design for different levels of performance and quantifies performance in terms that are accessible to nontechnical professionals

  2. Collapse risk of buildings

    • Misunderstanding: The Code collapse goals (10% or less chance of collapse after a major event, 1% chance of collapse over the life of the building) will definitely be met

    • Truth: Actual collapse risk of code-based buildings can be higher than intended

    • Limitation: No provisions in Code to explicitly verify collapse risk of design

    • Solution: PBEE requires quantifying the collapse risk

  3. Buildings subjected to low Intensities

    • Misunderstanding: A code-designed building will definitely not collapse at intensity levels lower than MCER.

    • Truth: A building designed for major events can still collapse at lower intensities

    • Limitation: Code does not design for intensities other than the major event

    • Solution: PBEE includes a range of intensity levels to quantify seismic risk more comprehensively


Other Comparisons


©2019 by C. Wolfe. Created with support from the Thornton Tomasetti Foundation.

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