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Embodied Carbon Structural Estimation Methods
Embodied Carbon Structural Estimation Methods

structural quantities, structure, embodied carbon

David Speedlin avatar
Written by David Speedlin
Updated over a year ago

Overview

The embodied carbon feature allows users to perform the following exercises automatically while providing the possibility of manual input and course-correction whenever needed.

  • Estimate the structural, enclosure, and interior material quantities based on building geometry or façade area takeoffs.

  • Assign Environmental Product Declarations (EPDs) to quantities.

  • Create a project embodied carbon profile summarizing the impacts of design decisions on embodied carbon impacts.

In order to build reasonable structural quantities estimates, cove.tool applies principles of structural engineering to create a conservative estimate for material quantities. The following systems are supported:

  • Frame Structures

    • Vertical Elements

      • Structural Steel Columns

      • Glulam Columns

      • Cast-in-Place Concrete Columns

    • Horizontal Beam/Girder Elements

      • Structural Steel Sections

      • Open Web Steel Joists

      • Glulam Beams/Girders

      • Cast-In-Place Concrete Beams/Girders

    • Horizontal Slab Elements

      • Composite Steel Decking with Concrete Top

      • Cross-Laminated Timber (CLT)

      • Cast-In-Place Concrete

You can select a generic system (like cast-in-place concrete) or mix and match from the above to meet the requirements of your project (like steel frame with CLT decking). Once you have selected the structural system and answered just a few specific questions about your project, cove.tool will be able to create a structural quantities estimate quickly!

In order to provide a conservative estimate, cove.tool uses a peer-reviewed methodology [link] to identify and estimate the structural quantities of a project. This approach is summarized below.

  • Create a typical load profile using the area weight average of the project’s live load, a typical dead load, and the selected building use types.

  • Identify the typical “worst-case” members which carry the largest loads.

    • Longest infill beams (span minimum of grid span between girders)

    • Longest interior and exterior load-bearing girders (span maximum of grid span between columns, carry the selected number of infill beams)

    • Interior and perimeter columns, which are grouped in vertical sets of three (i.e. each 3 floors, from the top down, will be estimated similarly)

  • Estimate the required sizes and assume that all other members of the same type are sized similarly.

  • Sum the quantities floor by floor to find the total material quantity estimate per element and material.

Once these quantities are computed, they are displayed and editable on the EPD Assignment page the embodied carbon feature.

Methods

Structural Steel

When estimating structural steel quantities, the standard AISC shapes are used as a reference. Standard Allowable Stress Design (ASD) methods from AISC 360-16 are used to calculate the required section modulus to support the load profile in beams and girders, which is then compared to the standard tables from AISC. Sections satisfying the section modulus conditions are then checked for deflection. The most economical, or lightest, section which satisfies both conditions is used to estimate the structural quantities.

In steel columns, allowable loads are computed according to AISC 360-16 methods and compared to the AISC tables. Interior and exterior columns are sized separately.

Steel Deck with Concrete Top

Corrugated steel decking is sized using practices and reference span and load tables from the Steel Deck Institute (SDI). Loads are calculated using the area-weighted average live- and dead-loads for the project in order to select a uniform decking profile to be used in the quantity estimates.

Open Web Steel Joists

Open Web Steel Joists (OWSJ) are estimated according to guidelines and references from the Steel Joist Institute (SJI).

Cross-Laminated Timber

CLT slabs are estimated using industry load and span tables for both flat slab and rib slab systems. The most economical option for the span is selected.

Glulam Beams, Girders, and Columns

Glulam profiles are selected from industry standard load tables and checked in bending, shear, and deflection where applicable.

Cast-in-Place Concrete

Cast-in-Place Concrete members are estimated using ACI 318-19/318M-19 methods for slabs, beams, girders, and foundation quantities.

Happy Modeling!


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