Struggling with structural grid for my project


Hi. I'm currently in my undergrad and am basically having to learn everything without real tutor help due to COVID-19 so please be kind - I know this should be easy!

I'm really struggling with the idea of a structural grid due to the shape of my building. It has a central "core" and 2 "wings", with the west wing being 2 floors, growing to 3 floors on the east wing (one long sloping roof).

Floor one overhangs on the south facade (hence the south shade on the ground floor image).

Here is my attempt at a grid. My final version won't be in different colours, it's just to help me for now. On most of the "crossings" I have put a black dot for columns. I haven't put columns in all as I've heard you can span 12m without needing them. The structure will be steel beams and columns and composite deck floors.

I have also put 4 shear walls - I have no idea if they are big enough or in the best locations etc.

I've tried so many different versions and I'm getting completely stuck on this and it's really holding me back now. Any help would be really really appreciated. Thank you.

Apr 9, 21 1:41 pm
Wood Guy

Looks reasonable to me. 

Apr 9, 21 3:46 pm  · 
1  · 

Agree with Wood Guy, though I do see this unnecessary long span, where you could easily bury another column.

Apr 9, 21 3:55 pm  · 
3  · 

And the column line at the top of the page runs to the left and appears to be supported on a beam at the perimeter. Dropping a column for that would probably help.

Apr 9, 21 4:27 pm  · 
1  · 


I'm so sorry I'm not sure which one you mean? If you are happy to clarify further I'll add a numbered grid below. Thank you

Apr 9, 21 4:53 pm  · 

@citizen Yes I wasn't sure in that area whether to add another green grid line or whether it was fine without since it was close to the lift core! Thank you

Apr 9, 21 4:55 pm  · 

Numbered grid:

Apr 9, 21 4:54 pm  · 

You're missing one between 11 and 12. And the area around 10/11/14 could be cleaned up by moving the column at 10, to the intersection of 11 and 14, by hiding the column in that curved wall if that's your thing

Apr 9, 21 8:05 pm  · 
1  · 

Key is to be able to find each point / grid line intersection in space so it's alley nice to have some sequential link between each skew in the plan, versus some random placement.  It's looks like what you have done is acceptable.the space between the 15 / 16 looks suspiciously large so you might consider another point in their depending on your roof design.

Apr 9, 21 9:04 pm  · 
1  · 

thank you so much for everyone's help - i will adjust accordingly. glad to hear i wasn't as far off as i thought i was!

Apr 10, 21 9:00 am  · 

I think, with an added column near the elevator, or using the elevator shaft walls as a bearing structure and the elevator shaft can also double as a shear wall you have a good start.  

Some things to consider:

If you can keep the spans, and the areas they support relatively similar then the beam size and most importantly the depth can stay the same.

Duct-work and to a lesser extent plumbing is something to consider when laying out columns.  When I design hospitals we put columns on either side of the corridors so we have very small beams over the corridors and more space to run ducts and plumbing.

In grid zone 1 and 3 you have beams forming a connection in the middle of a room with no column.  The beams splitting the rooms down the middle might be redundant and simply spanning the deck/slab between the beams that span from exterior to exterior may be more efficient structurally.

The auditorium is an ideal location to use bearing walls or to bury a lot of columns and use trusses or smaller beams closer together. For acoustical reasons it is good to structurally isolate the auditorium and not have steel beams pas continuously through the acoustic envelope, break this with a column or bearing point.

Steel decking or composite slabs (steel deck and concrete) typically span 5 feet maximum between trusses or beams.  Trusses are more efficient when you can keep the length and spacing consistent.  The irregular shapes of the bays (the space bound by columns typically 4) lends itself to using 2 way reinforced concrete. The advantages of the concrete slab is they can span efficiently these irregular shapes and you can use a steel beam or a composite concrete and steel beam as you have laid it out so far.

When drawing the plans up for an irregular shaped building I have the columns grid lines extend out beyond the building and I dimension the short and long span between non parallel grids as well as dimension the angles.

This looks like an interesting project.

Good luck

Peter N

Apr 12, 21 7:31 pm  · 
1  · 

Thank you so so much for all of this. I've adjusted a few things to take into consideration all your points, and even better I actually feel like I understand it better after your explanation! :)

Apr 21, 21 2:00 pm  · 

My undergrad never cared about structure grids. Or structure itself. They are all about big ideas. Hey, who says it has to be a grid with post and beams. Just do a thick concrete slab structure and place your columns strategically based on the layout. Let your engineer calculate the slab thickness, reinforcements, column sizes. Or precast concrete span the whole way with large beams at the perimeter. Or do a custom perimeter truss for a column free layout. Having a funky inefficient shape and then goes for efficient structural grid is just funny to me. Its not like you have a budget for your weird shape imaginary building.

Apr 21, 21 3:50 pm  · 

Jay1122 My Undergrad was the opposite we had to ensure our design studio project took into account the technical skills we were learning concurrently in other classes. We even had real non architects as clients for our hypothetical projects. these ranged from faculty from the aqua-science department to forest rangers and education faculty for the nature museum we did in the Shawnee National Forest. 

 The constraints of reality can often trigger more interesting design responses. Ignoring codes gravity and just putting a grid up haphazardly and letting someone else figure it out is lazy and reinforces the attitudes that are devaluing what we do as a profession.

Over and OUT

Peter N

Apr 23, 21 9:46 am  · 
1  · 

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