Abby Cripps

Link to Design Journal
Journal Entry For
Module 8 - Share Your Design
Created By
Abby Cripps
Property
Related to 120C/220C Students - Spring 2022 (1) (Related to Design Journal Entries | Winter 2022 (Linked Student))

2 units

How much carbon?!?!!

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The SEI 2050 (Structural Engineering Institute) goal is to reduce carbon emissions caused by the structural building materials by 2050. To reach this goal designers need to know how much embodied carbon their buildings have. To help them with this, the configurator tool Carbon?! has been created. This tool aims to allow for designers to create a standard concrete building in Revit. The tool will also provide structural outputs so structural engineers can see the effect of have a more sustainable concrete mix on their building.

Read Me - Carbon?!

This configuration tools allows for a designer to dynamically change their building design and view its effects of the embodied carbon along with the building period, base shear, material cost, design column strength and required column strength. The core building design is concrete columns and post-tensioned slabs. This will be particularly useful for structures like a parking garage where these are the main elements.

The following inputs allow changes to building design: Building length, building width, floor to floor height, number of floors, number of columns in both x and y directions, cantilever, and live load. Additionally, inputs for the selection of column and floor type are included to allow for the desired structure to be created. These inputs allow for a model to be created like the one seen below.

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Beyond simply allowing for a dynamically changing Revit, model key structural outputs are computed. Additional inputs that give detailed information about concrete are also used: Original concrete compressive strength, percent fly ash replacement of cement, cement, water, aggregate, sand, embodied carbon of cement.

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The above images show what you can expect from the Carbon?! tool. It shows the required and design column strengths as a check for the designer to ensure that columns are meeting the strength needed to support the structure. Additionally, the effect of adding more fly ash will lower the design strength so the designers can see what the optimal tradeoff between strength and embodied carbon it. Finally, it is best practice to delete the Revit model between runs of this tool. A video is attached below to show how the Carbon?! tool works.

Video:

The video below gives a brief explanation of how to use the Carbon?! tool.

Workflow:

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The overall workflow of the configuration tool Carbon?! can be seen above. There are 15 groups that make up the tool workflow.

Inputs:

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The above three node groups show all the inputs that the user can change for their design. Research has been done to determine accurate values to start but the user can change any values they desire.

Geometry:

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The above three nodes create the Revit geometry. The number if floors and floor to floor heights are used to determine the elevations of all floors. This is then used to create lines and rectangles that are then used to create columns and slabs.

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The above three groups compute key values needed for the analysis of the structure. The volume and area are found by using the geometry inputted into Revit. The material weight is determined based on concrete mix design.

Analysis:

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The period is a rough valuation based on number of the number of stories. The material cost is determined by the price and volume of concrete. The embodied carbon is calculated primarily based on how much cement the structure contains because that is the main source of embodied carbon. Increases in the fly ash in the concrete mix reduce the amount of embodied carbon of the building.

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The python script takes the mass of the floors and the story stiffness as inputs. The mass and stiffness matrices are created. Then the eigenvalues are found and used to find the base shear.

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Finally, the required and design compressive strengths of the columns were computed to allow for the designer to check if there building is structurally sound.