3 Units - Ted Bolte
Step 1 - Generative Design Framework
Design Decision #1: Beam Design
- Objective: What is the best beam design for this given structure to minimize cost, but maximize a reasonable factor of safety against loading, as well as the constructability?
- Model:
- A model would solve through problem by determining the best beam size given different design variables about the structure
- Design Variables
- Expected Loading (changes with beam self-weight)
- Spatial Constraints
- Fabrication
- Constants
- Material
- Evaluators
- Cost (minimize)
- Factor of Safety against loading (maximize, but within reason)
- Constructability (maximize)
- Most Important Tradeoffs
- Minimizing cost vs maximizing factor of safety
- Maximizing constructability vs minimizing cost
- Spatial constraints vs constructability
Design Decision #2: Beam Spacing
- Objective: What is the optimal spacing for the beams in this structure to minimize cost and deflections, while maximizing the constructability?
- Model:
- A model would help by evaluating different beam sizes and layouts to determine what spacing is optimal for the structure
- Design Variables
- Architectural Layout (different structure options to design for?)
- Beam Sizing (are there different beam options affecting the spacing?)
- Beam Material (what different materials are being considered?)
- Constants
- Maximum allowable beam spacing
- Evaluators
- Cost (minimize)
- Constructability (maximize)
- Deflections (minimize)
- Most Important Tradeoffs
- Beam Sizing vs Minimizing Deflections
- Cost vs Constructability
- Beam Material vs Cost
Design Decision #3: Skyscraper
- Objective: What is the optimal build for my skyscraper to minimize costs, construction time, and environmental impact of material, but maximizing the available floor areas?
- Design Variables
- Height of Structure
- Dimensions of Base
- Taper or not
- Material
- Constants
- Allowable Footprint Area
- Height Between Floors
- Cost per Volume
- Evaluators
- Cost (minimize)
- Time to construct (minimize)
- Available floor area (maximize)
- Environmental Impact of Material (minimize)
- Most Important Tradeoffs
- Cost vs Construction Time
- Construction Time vs. Environmental Impact
- Available Floor Area vs Cost
- Available Floor Area vs Construction Time
- Important to note that the three design decisions evaluated above do not encompass all of the design variables or evaluators, but are mere examples of what can be used in these specific design decisions.
Step 2 - Generative Design Study
Design Decision #3: Skyscraper
- Objective: What is the optimal build for my skyscraper to minimize costs, construction time, and environmental impact of material, but maximizing the available floor areas?
- Design Variables
- Height of Structure
- Integer Slider between 100’ and 1000’ at increments of 100’
- Dimensions of Base
- Integer Slider between 50’ and 100’ at increments of 5’
- Taper
- Integer Slider between 10’ and 20’ at increments of 1’
- Material
- Integer Slider between 0 and 2 to choose between Concrete, Steel, or Sustainable Alternative
- Constants
- Allowable Footprint Area
- 5000SF
- Height Between Floors
- 14ft
- Cost per Volume
- $160/CF (based roughly on Willis Tower in Chicago)
- Evaluators
- Cost (minimize)
- Function of a material multiplier, cost per volume, and volume
- Time to construct (minimize)
- Function of material time, height of the structure, and cost of the structure
- Available floor area (maximize)
- Based on the geometry of the entire structure and height between floors
- Environmental Impact of Material (minimize)
- Based on Construction Impact [2], Lifetime Impact [1], Strength [4], and Transportation Impact [3]
- Each of the three materials are ranked between 1 and 3 for each of these categories
- These impacts were also ranked in terms of order of importance for this given study (shown in brackets)
- Most Important Tradeoffs
- Cost vs Construction Time
- Construction Time vs. Environmental Impact
- Available Floor Area vs Cost
- Available Floor Area vs Construction Time
The design decision from step 1 that I decided to go with was the skyscraper, because I thought that would be the most exciting to use Generative Design Framework within Revit and Dynamo. I started out with three design variables and three evaluators, but I became interested in seeing the different outcomes, that I decided to go up to four design variables and four evaluators. This allows a project manager to have more information when deciding on an alternative. The four inputs that I decided to use in this Generative Design Study were building height, base length, primary material used, and taper over the height of the structure. There were a few constants that I wanted to set for this design study because there are often certain constraints on a project. The constants for this design were: allowable footprint area, the height between floors, and the cost per volume. There were some tradeoffs from the implementation of these different inputs in the model. The evaluators were total floor area, time to build, cost, and material environmental impact. These inputs and outputs allowed for some tradeoffs to be identified between design decisions and outcomes. They also allowed for some linear relationships to be identified. Both the tradeoffs and linear relationships are important for a project owner to make a decision regarding the design of their skyscraper. This is because they can evaluate the marginal cost (or benefit) of each design decision, allowing them to prioritize what they believe to be the most important.
Step 3 - Generative Design Study Results
The above scatterplot is comparing the different designs in a number of different ways. On the x-axis is the estimate time to build structure and the y-axis is the cost, both of which were set to be optimized to their minimum in this generative design. The size of the dots represents the materials environmental impact, which means that a smaller dot is a better design option for the environment. The color of the dots represents the material used in that design, with red being concrete, green being steel, and then blue being a sustainable alternative material.
There are a few takeaways from this scatterplot, with the first being how the time to build the structure and the cost are not linearly correlated for either material, instead they have a slight hyperbolic nature to them. Second, is that the steel, for the way cost was analyzed in this design, resulted in higher costs at each estimated time to build the structure. The steel did show significant benefits when comparing the environmental impacts of the material, as can be seen by the differences in sizes between the green and red dots. This graph could be used in choosing a design because it would allow a project owner to decide what they value most: cost, construction time, or environmental impact. There are other metrics that could be evaluated in a similar manner, but this graph best displays the different benefits and drawbacks of each of the alternatives.
Images from Dynamo:
