Structural Bay Size Optimizer
A generative design assistant for architects and engineers during schematic design
Intended users
Users: Structural engineers, architects, sustainability consultants
Need you’re trying to provide a solution or support for
What problems do they face?
- Designers often guess initial bay spacing and floor heights using rules of thumb.
- These assumptions significantly influence structural spans, system weight, and mechanical clearances.
- Carbon and cost estimates are rarely quantified at this stage, even though early decisions lock in long-term impacts.
Need: Early design decisions like bay width have major implications on structural efficiency, material use, and embodied carbon.
Inputs
Variable Input Name | Description | |
Number of Bays X | User-selected horizontal and vertical grid spacing | Variable |
Floor-to-floor height | Impacts story height | Variable |
Structural system type | (e.g., steel moment frame, concrete beam-slab) | Variable |
Building footprint | Total length | Variable |
Point Load (P) | Horizontal or vertical force at any node (user-defined) | Variable |
Uniform Line Load (w) | Applied in Z-direction (gravity); distributed load per bay | Constant |
Material database | Includes density, strength, and embodied carbon (kg CO₂e/m3) | Constant |
Underlying logic of the model you’ll implement
- 2D Frame Generation:
- Create a single-story 2D frame in Revit based on bay width and height inputs.
- Generate nodes and members with pinned supports at the base.
- Loading and Statics:
- Apply user-specified point load (P) at any node (horizontal or vertical).
- Apply uniform user specified + material-related gravity line load (w) on all beams.
- Solve for member axial forces, shears, and bending moments using statics.
- Member Design Check:
- For each beam and column, compute Demand/Capacity (D/C) ratio
- Demand: internal axial/shear/moment due to applied loads
- Capacity: based on material strength and cross-section
- Performance Metrics:
- Total structural weight: computed from section areas and material density
- Embodied carbon: computed from material volume × density × CO₂e/kg
- Demand/Capacity (D/C)
- Generative Optimization Logic:
- Multi-objective evaluation based on:
- Minimized embodied carbon
- Minimized material weight
- Maximized D/C ratios (≤ 1, no overloads)
Where:
Outputs
Type | Output Description |
Visual (Revit) | 2D framing layout auto-generated based on chosen bay size |
Weight | Table of material takeoffs (lb) |
Sustainability | Total embodied carbon summary (lb CO₂e) |
Strength | Demand Capacity ratio per element |
Exportable | CSV or Excel of assumptions and performance metrics |