Ethan Sun

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Journal Entry For
Module 8 - Make Your Pitch
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Ethan
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Related to 120C/220C Students - Spring 2022 (1) (Related to Design Journal Entries | Winter 2022 (Linked Student))
EBFs in the Huang Engineering Center, Stanford University
EBFs in the Huang Engineering Center, Stanford University

There are many structural systems available for a steel-framed building, with the most popular one being the steel moment frame. It is very spatially efficient, with no diagonal members between floors that can take up valuable interior space or impact the exterior look of the building. Thus, they are beloved by architects, who may want to conceal the structural system of their building.

However, engineering always has compromises. The steel moment frame structure has some fundamental drawbacks, especially in seismic regions. They have relatively low stiffness, which means that their designs are almost always “displacement-controlled”. Very large members have to be used to limit the displacements and drifts, but the force and moment demands in these members can be much lower than their capacities, which makes the building structurally inefficient and more expensive. The connections have to withstand large deflections under seismic loadings, thus they have to be carefully designed and detailed, further increasing costs.

On the other hand, other systems such as buckling-restrained braced frames (BRBFs) and eccentrically braced frames (EBFs) are much more efficient structural-wise. They are very stiff, which can also improve occupant comfort in windy locations. Although some deem such braces to be “ugly”, good architects would be able to combine such systems with their architectural design elegantly, or even express these elements as part of the design.

Thus, it would be a good idea to at least explore the possibilities of the BRBF and EBF structural systems.

Intended users

The intended users of my tool are engineers and architects who are conducting the conceptual design of a low to medium rise steel frame building.

Need you’re trying to provide a solution or support for

Explore and compare the use of a steel moment frame, a buckling-restrained braced frame, or an eccentrically braced frame as the structural system of a steel-framed building.

Automatically create the desired frame in Revit.

Provide evaluators that may assist decision-making.

Inputs

Revit mass that represents the form of the building.

Either the desired grid layout or the range of acceptable span lengths.

Number of stories.

Structural system to use (SMF, BRBF, EBF)

If BRBF or EBF chosen, whether the braces are on the exterior or interior.

Underlying logic of the model you’ll implement

Users will provide desired parameters that will serve as the inputs to a Dynamo graph, which generates the basic geometry of the frame. Revit elements will then be placed using that geometry. Finally, some evaluators will be reported either directly from Revit, or by computations in Dynamo.

Outputs

Revit frame of the structure.

Approximate weight of steel required. → Cost

Proportion of façade with braces.

Proportion (measured by number of bays) of interior space blocked by braces.

Perhaps provide some structural calculations? (e.g. deflections)