Step 1 - Generative Design Framework
A very brief description of the design decisions from Step 1 following the Generative Design Framework.
- Design Decision 1: Organizing the work of different crews spatially on the construction site
- Design Variables
- Size of crews
- Number of crews
- Workspace needed for each crew to conduct their work
- Time that key activities need to be conducted on site
- Evaluators
- Construction Cost
- Schedule duration on the critical path
- Most Important Tradeoffs to Consider
- Construction Time vs Construction Cost
- If the crews are allowed to be more spaced out, the construction duration increases. The construction cost may decrease because less crews are needed for the job and there is less of a capacity crunch.
- Design Decision 2: In construction logistics, the arrangement of materials on a truck so that the least transport is required (“tetris”).
- Design Variables
- Size of materials
- Shape of materials
- Weight of materials
- Evaluators
- Utilized storage capacity of truck
- Total transportation miles incurred
- Timeliness of material deliveries
- Most Important Tradeoffs to Consider
- Cost of transportation vs Speed of delivery
- It may be cheaper to transport a full truck rather than a half-empty truck. However, a full truck may require more time to be loaded fully before it can leave, so it may take longer before the materials are delivered.
- Cost of redesigning materials to fit the dimensions of the truck vs Cost of transporting existing unoptimized design
- Design Decision 3: From a structural engineering perspective - a concrete column that keeps material weight low but satisfies the cost and loading requirements of the structure
- Design Variables
- Weight of the concrete column
- Thickness of the top/bottom flange
- Length of the web
- Thickness of the web
- Material used to construct the concrete column
- Evaluators
- Material cost of column
- Cost for painting exposed surface area of column
- Tensile/Compressive Load Bearing Capability of Column
- Torsional Bending Capability of Column
- Most Important Tradeoffs to Consider
- Load-bearing capabilities against cost of material utilized
Step 2 - Generative Design Study
Objective: What are the ideal dimensions (width and length) of a column that will minimize surface treatment costs while being able to maximize load bearing requirements?
Model: A simple rectangular column was created to test design decision 3 - a concrete column with low material use and satisfies loading requirements.
Design Variables:
- Width of Column
- Length of Column
Inputs - Constants:
- Height of column
- Surface material cost per unit surface area
- Volume material cost per unit volume
- Compressive strength of concrete
Evaluators:
- Total surface material cost (e.g. for painting the structure, fire-proofing)
- Total volume material cost
- Load bearing capability of the column.
We assume that the compressive strength is constant, and the load that the column can withstand is given by F = CS * A where CS is the compressive strength and A is the area.
Interpretations and Trade-Offs
- Loading capacity and surface material cost
Since the loading capacity is only affected by top surface area and the height is constant, there is no trade-off between the loading capacity and the volume material cost. However, there is a trade-off between the loading capacity and surface material cost as shown in the scatter-plot.
We would like to calculate the different costs based on a high-level estimate of the costs per unit area and costs per unit volume. Material costs and treatment costs likely differ in their scale of magnitude but these constant inputs can be modified.
Step 3 - Generative Design Study Results
- The scatterplot shows that loading capacity and surface material costs do not follow a strict linear relationship, i.e. there is an element of trade-off between the two output evaluators. Overall, the higher the surface material cost, the higher the loading capacity, since the height of the column is kept constant, and surface material cost varies only with the width and length of the column. There are some options with a high material cost but low loading capacities - these should be avoided in choosing design of the column.
The Dynamo study graph is shown below:
