Which structural framing systems and materials are most commonly used in the United States for residences? For office buildings?
◦ What factors explain why those dominate?
Light-frame wood dominates for small residential homes and low-rise apartments, with concrete podiums used for larger mid-rises. Offices mostly use steel or reinforced concrete, with steel more common as height increases. Cost, supply, local labor, environmental conditions and impact, and municipal requirements can impact the choice. Wood is cheaper and fast, while steel can give long open spaces.
◦ Why did you choose your system, and what did it cost you?
I chose wood sitting on a concrete podium because residential floors want more closely spaced support regions for individual units and it has the lowest carbon cost. It cost me a transfer slab where wood lines are missing podium columns and needing to design two different structural systems. Also potentially needing to remove the top floor.
You sized members by judgment rather than analysis.
◦ What did you base your first guess on?
My guesses mostly came from suggestions from the assignment review as well as the graphic shown in the recording. Searching generic and common sizes also.
◦ Why is it safer to guess large and shrink than to guess small and grow?
Shrinking frees up space while enlarging takes away space and can increase collisions.
◦ At what point in a real project does the engineer take over from the guess?
The engineering takes over after the schematic is set. This can be early in design development when loads and structural systems are analyzed and permits/final drawings are sought.
Design teams link and share models rather than working in one file.
◦ What are the advantages of linking?
Each discipline can own and edit its own model that really just shows what is relevant to them without doing it on one overlapping model. This also helps files stay smaller and flow smoother.
◦ What errors does linking make possible that a single model would not?
Links can break, as they did over and over again for me. They can also not update and go out of date so teams end up working on different model versions without realizing.
◦ Why is getting shared coordinates right at the start so much cheaper than fixing it later?
All of the elements reference these coordinates, so one error with them can spread to every element. Fixing it later means moving absolutely everything.
Not every clash is a problem.
◦ On what basis did you classify a clash as an issue versus not an issue?
◦ Who should have authority to close a clash on a real project?
Your beam depths just constrained next week's ductwork.
◦ Where in your building is the ceiling plenum now tightest?
◦ What would you give up to get it back?
◦ Should the structural engineer have consulted the mechanical engineer before setting spans?