Interesting Roof Structure 1

[phamENG]

Reading through the news this morning and came across an article with a picture of an interesting roof. It's a grain storage building in Ukraine. I'll let you guess why there's a large hole in the roof.

But I'm interested in the framing. Looks like a castellated steel rafter system with a turnbuckle tension tie. Has anyone seen one of these before? Does it have a name? Any comments on the possible merits or faults with it?

 

[dik]

Are those castellated? or are they beams with holes cut in them?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[dik]

Blodgett had a really good description of the design and fabrication of them.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[phamENG]

Are those castellated? or are they beams with holes cut in them?

If I may be a bit pedantic, they'd be cellular...but looking at them again in that picture you're right. They're just holes. The proportion of open to solid web is wrong for a true cellular beam.

 

[WinelandV]

dik,

They create that 20" deep beam from a W14x22.
[Edit: I'm an idiot who read too fast. Feel free to ignore this.]

 

[dik]

Thanks, I know how it's done... it's just whether it was done. I don't know. With the radii for the 'arches'... I don't know if they created the deeper castellated beam and then rolled it to a radius, or what?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[phamENG]

dik - good question. I've never done a curved beam like that, so I've never put much thought into how much residual stress might be stored in the web. I imagine you'd have more risk of web buckling during bending at that radius with the holes already cut out than you would by cutting them and getting some distortion from relieving the the residual stress, but I don't have any numbers to back that up.

 

[phamENG]

Talked to a fabricator today. He said it would probably be cheaper for him to build his own open web steel joists in his shop than to do castellated beams. So that's that, I suppose.

Seems like paint/fireproofing would be the only cases where castellated could shine.

 

[Trippelsewe]

I love castellated beams but have only done them once in my 10 year career. Nowadays I only see them in applications where they are an architectural feature, eg link below. I think the labour vs material price does not stack up.

https://www.google.com.au/maps/@-42...067&pitch=0&thumbfov=100!7i16384!8i8192?hl=en

 

[phamENG]

Not sure which I'm more excited about: the castellated beams or the gelato barge...

 

[dik]

I think some facilities can automate the cutting and welding process...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[RontheRedneck]

My first thought was uplift from a high wind condition. That could put those ties in compression. No way would that work.

 

[HTURKAK]

Starting the guessing game ;

-The grain storage bldg subjected to air strike with suspicion of aircraft shelter ..


I have seen before .. the castellated steel rafter system nowadays is not popular..I looked to SNIP -II-23-81 ..It is named (PERFORATED WEB )

The use of tension tie for portal frames was also poular 40-50 yrs ago.

 

[hokie66]

As to the castellated beam sections, that was fairly common about 40 years ago in the US, mainly because architects preferred the look in preference to long span trusses. I did a few of them in that time for 100-120 foot spans over high school gymnasiums.

But the tied rafter structure using castellated rafters must have been a European thing. Not robust against wind uplift, or in contributing laterally.