Applying standard rectangular building pressure coefficients to structures with irregular plan shapes or unconventional roof geometries produces pressure values that do not reflect the actual aerodynamic behavior those specific shapes create.
Why Building Shape Changes Pressure Coefficients
ASCE 7-16 pressure coefficient tables are built around specific geometric assumptions — aspect ratio, roof shape, and plan configuration all factor into which coefficient set applies. A building with an irregular plan shape or an unconventional roof geometry does not automatically qualify for the same coefficients as a standard rectangular structure, because the actual aerodynamic behavior of wind flowing around and over an irregular shape genuinely differs.
Where the Generic Assumption Enters
Early-stage wind load calculations, particularly during preliminary design, frequently apply standard rectangular building coefficients as a starting simplification — a reasonable approach when the geometry is still being finalized. The risk is when this simplification is never revisited once the building’s actual irregular shape is confirmed, carrying a generic assumption forward into a calculation meant to reflect the final design.
Why Irregular Geometry Deserves Specific Evaluation
A building with a non-rectangular plan or an unconventional roof shape can experience pressure distributions that a standard coefficient set does not capture — potentially higher localized pressures at unusual corners or transitions that a rectangular-building assumption would never account for. This is not a marginal difference; it reflects genuinely different aerodynamic behavior tied to the building’s actual shape.
Adjusting Coefficients Based on Actual Geometry Classification
After explaining how aspect ratio and roof shape alter pressure coefficients from the standard case, the fix is classifying the building’s actual geometry and applying the corresponding coefficient set, rather than carrying forward an early-stage rectangular assumption into the final calculation. Wind Master adjusts the coefficient set based on the building’s actual geometry classification, ensuring irregular shapes receive the specific evaluation their aerodynamic behavior requires.
Validate your geometry-based coefficients — Audit your building shape inputs.