Does anyone know what these portal frames are called in the US? 4

[RobFerrano]

Hi everyone,

I'm a civil engineer who recently ran into a couple of interesting types of portal frames used in Germany. I've been trying to figure out if these are used in the US at all, and what they are called, but all my colleagues have been equally stumped. I have attached a very simple drawing showing each one of them. With my basic German, I can infer that they are called (in German) single-hip and double-hip frames, but for the life of me I can't recall having ever seen them in the US in any application, and was wondering what they would be called here, if anything. I'm afraid I'm too used to seeing rigid frames and two and three-hinged frames.

Thank you for your time,
Robert Ferrano

PS. There's also a peculiar type of pad foundation that they use (I recently had a meeting with a group of German civil engineers who are working on a project, which is how I came across these things):

http://de.wikipedia.org/wiki/Köcherfundament.

It's basically a reinforced concrete pad footing with a socket base that absorbs bending moments and holds the column in place during building. My German colleagues called it a "sleeve foundation," but I've never heard that used in the US. Does anyone know what we call these?

 

[BigH]

Robert - please don't double post. You posted in the Civil Engineering forum as well. it is quite frowned upon and someone may tag this for deletion (red flag).

 

[paddingtongreen]

Actually, the one is a three pinned arch and the other is a variation on it.
I once used those "L" shaped pieces, where the moment connection was made in a temporary building, on the site and then the pieces taken to the place and with four of them we made a square structure, then another, linked them with beams, and continued with this till we had a pipe rack. It was a way to keep working in an area with constantly changing, always bad, weather.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[hokie66]

I wouldn't call them arches. See my answer in the other forum. For analysis, you can just replace the vertical pinned legs with roller supports.

 

[RobFerrano]

BigH: I'm terribly sorry about the double post. I'm new to the forums and didn't know it was such a big deal. I just thought that the question concerned both civil and structural engineers, which is why I posted it on both forums. I will refrain from doing this again in the future - thanks for pointing it out. It's good to learn the rules of etiquette for new forums!

paddingtongreen: I thought three-hinged portal frames always had the third hinge at the ridge. Am I wrong here?

 

[msquared48]

Looks like they would be applicable for fairly light loads, and subject to more lateral deflection than a normal portal frame.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Lion06]

Interestingly enough, wind moment frame buildings behave this way (one end moment connected and the other pin connected).

 

[msquared48]

In Professor Ing A. Kleinlogel's book "Rigid Frame Formulas" from the 11th Edition, 1943, he has diagrams for 114 rigid frame shapes, all termed such. (Copy #1) This was the first American Edition, as translated from the original German "Rahmenformeln".

Personally, for the "Rigid Frame" shown, I would term it more of a rigid "bent" than a frame. But that's just me and being around the PEMB industry for a while.

I also checked the "Data Book For Civil Engineers" by Edwin E. Seelye, but found nothing there.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[hokie66]

SEIT,
What do you mean by "wind moment frame buildings"? Why can't they have more than one rigid joint?

I think when most folks talk about rigid frames, they mean indeterminate frames, but the frames posted by RobF are determinate, thus probably leading to paddington's comparison to a three pinned arch.

 

[msquared48]

He's talking about a bent Hokie., commonly used in PEMB's,

Just an inverted "L", pinned at both ends.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[dhengr]

RobF:
Lookin at your explanation in your other post...., If the Germans call those single hip and double hip, sorta relating them to our left hip and our right hip, what do they call that long stiff one in the middle?

 

[msquared48]

stiffie?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[RobFerrano]

dhengr: oh man, I was rolling on the floor laughing for a while there!

 

[Lion06]

Actually I am talking about a building with wind-moment connections for the lateral system. The lateral system is essentially top and bottom clips angles that are designed for wind moments only. This connection typically yields under gravity load moments. When The wind blows, the windward "moment" connection unloads (therefore it has rotational stiffness), but the leeward "moment" connection tries to load further (since it's already yielded under gravity load it behaves as a pin for the additional moment due to lateral). When the wind blows in the other direction, the same behavior occurs (with one connection unloading, and being effective, and the other loading further, therefore acting as a pin), just the moment connection and pin have swapped places.

 

[paddingtongreen]

I was taught that any frame with the three hinges is a three pinned arch. The shape may change but the principle remains the same.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[hokie66]

Understood, and I have heard others use the same definition. I only call something an arch if it depends primarily on compression.

 

[paddingtongreen]

At the risk of being a "threadjacker". Hokie, have you come across the "Rainbow" Bridge?

http://mathemati.ca/home.html

An arch made from straight pieces.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[vaquers]

Dear RobFerrano,
this type of foundation were very common for precast concrete columns in Germany (see Prof. Leonhardt books). Taking this into account, I supposed that this frames were built with precast concrete beams and columns. This could explain the "zweihüftig" frame. The second stage moment-connection between the beams and the central column is easy to solve, this is not the case of the extreme connections. Regarding the "einhüftig" frame im agree with paddingtongreen. I only add that the L-shaped element is feasible when its weight isn´t very high (because of transportation and erection). Regards,

Sebastian

 

[hokie66]

Sebastian,
Just because there are L and T pieces shown doesn't mean that is the way they are transported. There can be site moment connections, either welded or bolted.

Michael,
Your link didn't open for me. I googled "Rainbow Bridge", and found several with that name.

 

[hokie66]

Michael,
This time it opened. Nice description.