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BIM Troublemaker: Membrane Emulation and Suvarnabhumi Airport

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    BIM Troublemaker: Membrane Emulation and Suvarnabhumi Airport

    I have been fascinated by Bangkok's Suvarnabhumi Airport for years. I have spent hours in the immigration lines wondering how to create parametric models of the different forms throughout the building. The scalloped concourses represent a special challenge because of the extensive use of membranes.

    Right before christmas, i was up in the city doing my christmas shopping and it finally hit me! I could use adaptive components to emulate the membranes! Awesome. Here we go. The basic geometry is repetitive and symmetrical, so in this exercise, I will build a single bay and then repeat it later.

    First up I placed a single Reference Point (RP) at the origin in a Conceptual Mass Family. Then I placed 2 additional RPs in the same place, creating new parameters to control their OFFSET value. Then I hosted an parameter-driven ellipse on the vertical plane of each RP.

    With this basic work done, I adjust the RPs into position shown below. I hosted a third RP at the intersection of the ellipses for use later on.

    Next up, I created an extruded form using the upper-most ellipse. Controlling positive and negative offsets using parameters as well.

    The form of the concourses are extruded tubes with wedges cut out. Now that i had the tube, I need to cut the wedge.

    I went back to that first RP at the origin and mounted three more points. The offsets of these also controlled by deliberate parameters. The topmost RP was linked to the overall height of the form, with 1000mm added to avoid errors. The bottom RP is intended to be manually matched to the RP which lives at the intersection of the ellipses. The RP in the middle is controlled by a ratio of the overall height.

    Then, on the vertical planes of these 3 new RPs, i mounted another pair of RPs, controlling their offsets parametrically as well. Connecting the points using lines, I end up with trapezoid like you see below (this is a lot easier to understand if you play with the family posted below!)

    With that trapezoid created, I can extrude and subtract it from my initially extruded ellipse.

    At this point, I create an adaptive component which is made of 3 points and a model line curve connecting them.

    Inserting the adaptive component into my original family i host its points on the edges of my wedge-cut AND the other, lower, ellipse from step one of this exercise. I make sure that the points at the edges are hosted at the intersection of the edge and the plane of the middle point.

    With the first one set, i can drag several copies along the line, adjusting their hosted position so they are all equidistant.

    Select all the adaptive components, hit the Create Form button and BANG!

    Now i have a parameter driven surface that looks and behaves a lot like a membrane!

    And then when i start to multiply it out it gets right to the basic geometry i am looking for.

    Conquering Bangkok one useless model at a time!

    You can download the model here

    Click here to view the entire blog post.

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