Overall Strategy & Features:
My primary goal was to avoid having the framing system exposed on the outside of the building. I want the building to beautify its surroundings as much as possible with a smooth, lichen and plant-covered exterior without bulges from framing elements.
I created a standard rectangular grid system for the interior core of the building to support its central rectangular shaft for stairs and elevators. I then created a radial grid system to facilitate having a core of circular load-bearing structural walls and structural columns in hexagonal arrangements. I had the outer ring of columns tucked in about a foot from the edge of each floor to ensure it wouldn’t intersect the sloping exterior walls.
I then added beam systems to ensure that the floors had enough support at each level. I am least confident about my framing for the top level of my building, which features dramatic overhangs. If I were to re-do this assignment, I would consider making the floor of this level lighter and using timber framing instead of steel to have the lightest possible weight. I think that, in reality, it is quite likely the overhanging petals would require buttresses, or that the petals would have to be shorter.
Materials & Framing System:
I used a steel framing system.
- W10X33 Steel Columns
- W12x26 Steel Beams
- 12” Structural Retaining Walls
- 1.5” Structural Floors (3” LW Concrete on 12” Rigid Insulation on 2” Metal Deck)
- 6’x4’ Isolated Concrete Footings
Location & Major Framing Elements:
I used copy-monitoring to copy over the levels, floors, and innermost circular walls of each level. I then converted these floors and walls into structural elements to avoid remodeling them from scratch (which was important given how much time I ended up investing in drawing beam system boundaries). The floors have equivalent composition to my architectural model, but are marked as structural elements. I made the structural walls into 12” concrete retaining walls, which are much sturdier then the thin, interior walls I used for the architectural model. Without doing any calculations, I felt the 12” retaining walls were the best default option for load-bearing structural walls.
I then set 4 structural columns to mark off the central shaft of my building (which contains stairs and elevators) and used beams to connect them with a hexagon of 6 columns embedded within the circular structural wall. I then used beams to connect these 6 columns with a second hexagon of 6 columns of greater diameter tucked inside from the exterior walls in the architectural model.
I adjusted these features to ensure that no framing elements protrude from the building as the tower segment slopes inward as it gets taller. I then outlined the petals of the final level with columns and traced the outlines with beams, making each petal have one large beam system to support its portion of the roofing.
Structural Challenges:
My biggest structural challenges came from my building’s cylindrical segment having an inward slope. This meant that I couldn’t simply design the structural framing for the first level and then paste it into all of the other levels, so each level had to be customized individually. I was fortunately able to paste the core of the building, however, which consists of a circular load-bearing wall and structural framing that surrounds the central shaft for stairs and elevators.
Unfortunately, I had some severe issues alignment issues, likely building upon earlier misalignments I had in previous modules. For whatever reason, I was unable to create automatic beam systems. This meant that I had to manually draw the boundaries of every single beam system in the building, which took several hours of effort. It was kind of zen, so definitely not all bad, but I wish there would have been a way to do it more quickly.
Should I have beams connecting the bottoms of the petals’ structural columns, or are the floors enough?
Coordinated Views:
Right away I can see that I didn’t tuck my outermost structural columns inward quite far enough, as they’re clearly exposed through the exterior walls. Whoops! I’ll have to fix that. Fortunately it looks like I positioned them properly for all the other levels, so it shouldn’t be too much work.
I like how the outermost structural columns are embedded within my exterior walls, but I can see that my beam systems are embedded within my floors, which is not what I wanted! I want the floors to rest on top of my steel framing, so this means my architectural floors are an entire foot thicker than I thought they were. Sure enough, my structural floors are 1.5’ and my architectural floors are 2.5’. Strangely, my architectural floors show that they are composed of 2” steel deck, 12” insulation, and 3” of LW concrete, but this somehow is adding up to 2.5’ total. Weird. I should probably try resetting their composition.
I can see that my beam systems are working as intended for my highest level, at least. I like the view from within my petals. I would consider adjusting the specific positions of the columns and or mullions so that they could be more aligned, as that would likely look nicer.