Statics
 

As i was watching BMO rise with the diagonal steel work, i was also reflecting when I had taken Statics and Dynamics courses at Michigan Tech when i was getting my 1st degree in Chemical Engineering. Both courses were eye openers.

I too have a degree in Chemical Engineering and have fond memories of learning about wonderful "K" Truss... My father worked as a structural engineer for SOM in the late 60's early 70's when the Big 3 were going up in Chicago and as a child he taught me about the X bracing on Hancock and the Tube/Bundle concept for the "Sears" Tower.. You could say I was raised as a skyscraper geek.

Oct 15



Yes there are some round headed fasteners - as well as bolt heads and bold ends.

They gotta a new website
Link: https://320southcanal.com

And a new brochure: https://320southcanal.com/wp-content.../eBrochure.pdf

Not really a fan of the building design, but at least there's a cool rendering from the site's main page:
https://320southcanal.com/wp-content...nt/01-hero.jpg

Can someone explain where the loads go from the inverted triangle trusses that seemingly "dead end" at the header beam to the left & right of the central V columns?

I mean, I guess I see that they're directed horizontally to the ground-connecting-columns, but it seems so abrupt. Interestingly, the angled, horizontal support structure coming off the cores appears to split tie difference between the inverted triangle's apexes.

I would have guessed that addt'l structure would have connected directly to those nodes on the header beam

Yes ^

Think of the floor with all of the diagonal beams as a single truss... similar to a truss that holds up a bridge. And, like a bridge truss, (or a 'space frame', which is just a different kind of truss) every 'bottom structural point', if you will, does not need to be supported to maintain the structural integrity of the overall truss.

Having said that, if you look closely, the diagonal columns that are transferring the dead loads from above directly to the level 1 columns appear to be sized just a little bit larger to account for those loads... and although it's been a long time since my undergrad structures course, I would suspect the diagonals that are 'not connected' are actually in 'tension', meaning they are 'hanging' the floor below while the others are in 'compression' that are actually transferring the vertical loads to the ground level angled columns.

The angled beams in the 2nd floor appear to be simply adding additional 'shear' strength to the floor for what appears to be kind of a cantilever where the 'missing' vertical columns would have been.

^^^ Looking at that rendering and realizing what we do now, I love that they’re hiding the diagonals in tension, leaving only the most structurally important columns/diagonals visible. Nice touch Goettsch!

Forgive my naïveté but I did not realize that this was so close to the Post Office, and that the post office and Union Station were so close to each other. *facepalm*

If the post office redevelopment is as much of a game-changer as some in the industry believe it is, as is stated in the cross-posted link below from the 301/321 S Wacker thread, then we could see a flurry of new development in this corner of the West Loop as we already are near Fulton Market.

Apologies for the run-on sentence :P

Ahh ok! This helps explain a lot. Thank you! It's very fascinating how that one detail totally changes how I "see" the loads transferring when I assume they're hanging that part of the beam. Wild.

Thanks for the link. https://320southcanal.com/ has a really snazzy/jazzy video too of the project I haven't seen. It shows an entrance to 'Union Station Tower' from Union Station. I believe I read somewhere that they will be connected underground. Presumeably they'll have to dig up Jackson at some point to do this. Not sure the timing of that.

^That new video is really something

I'm over at Roosevelt and Wabash and have been waiting for the core to poke through. It finally has! :cheers:

Very excited to see what sort of presence it gives from my view!

https://live.staticflickr.com/65535/...ac9d33ff_c.jpgIMG_4352 by Andrew W, on Flickr
https://live.staticflickr.com/65535/...bfc41410_c.jpgIMG_4351 by Andrew W, on Flickr
https://live.staticflickr.com/65535/...89d6363a_c.jpgIMG_4348 by Andrew W, on Flickr
https://live.staticflickr.com/65535/...8047f972_c.jpgIMG_4350 by Andrew W, on Flickr

The underground connection actually already exists under Canal. It's the same that previously connected the station to its parking garage. It's a little less glamorous than the video portrays, connecting to the concourse near baggage rather than from the Great Hall. Developers and the station have previously looked at connections under Jackson, but it is too encumbered with utilities and the station's own underground driveways to make a link.

In either case most of Canal Street does not require digging, because it's actually a viaduct from roughly Van Buren to Washington and tracks 1 and 3, and 2 and 4 pass underneath it. There is a plan to reconstruct Canal Street in the near future as the 100+ year old structure is regularly dropping spalled concrete on the tracks and is the cause of regular leaks over the portion of the station concourse that exists under the street.

That video is jazzy indeed. I've just realized that FINALLY we will see something other than round V-bracing/columns! It appears they've selected hexagon cladding for the V-bracing here. HALLELUJA Looks great! :cheers::cheers::cheers:

Oct 29

It is funny because the reason I don't like this building is because it resembles 110 N Wacker so much. However, if I were to ignore the time of construction and the height, I actually like the geometry of this building more.

^Right. I actually feel like this is going to be the more interesting of the two.

Also the lowrise cell of the core is just about to drop off. Floor 15, which is the tall floor right below the climbing formwork in Harry's photos is the last floor before the first setback.

It's certainly going to be much more visible than 110 N Wacker. 110 is most prominent coming into the city from 290 and if you're ON Wacker or the River. BMO will stand out from that vantage point just as much (if not more), plus from almost any view from the south/southwest.

This thing is a beast...