Questions for the conceptual design of an avalanche protection structure

[hellophysics]

[Mentor Note: This thread was spun off from an old thread here:]
https://www.physicsforums.com/threads/type-of-joints-in-portal-frame.973132/

this is probably elementary: Is it possible to decide the flexibility of a joint between gluelam beam and reinforced concrete column? if I decide it to be flexible, can it still the corner frame take bending moments? or then it behaves as a simply supported beam?

 

[PhanthomJay]

this is probably elementary: Is it possible to decide the flexibility of a joint between gluelam beam and reinforced concrete column? if I decide it to be flexible, can it still the corner frame take bending moments? or then it behaves as a simply supported beam?

A flexible joint is a joint that is considered a pinned joint that is free to rotate the beam at that joint. Many beam to column connections are considered as pinned joints even though there may be partial rigidity in the connection. If you choose a flexible connection, the beam is designed as a simply supported beam, with no moments developed at the beam-column connection.

 

[hellophysics]

many thanks, I understand what you mean. My thought is: in steel for example, one can create frames that are bolted or welded. Welded frames are fully rigid while bolted frames allow for certain flexibility. Both allow frame action and therefore bending moments in the corners. I was wondering if between gluelam beam and reinforced concrete column one can also decide this according to the method of connecting them.

 

[Lnewqban]

I was wondering if between gluelam beam and reinforced concrete column one can also decide this according to the method of connecting them.

Yes, one can.
In my opinion, it is better not to transfer bending moments to any column via a horizontal member solidly attached to it, unless it is convenient for other reasons.

Welcome!

Are you referring to a portal frame type of structure?
If not, note that this is an old thread.
I recommend you to open a new one in order to get attention from a greater number of members, who can discuss details with you.
Perhaps, @berkeman can help with openining a new thread.

 

[hellophysics]

Thanks again. Yes, it's a portal frame structure with a timber beam and a reinforced concrete column in one of the two ends. In the other the column is in timber. That reinforced column is indeed attached to a reinforced concrete wall and both are fixed to the ground with a foundation as they are for snow avalanche protection.

As the frames I know are all from the same materials, I wanted to know if I could do one from two different materials. As the reinforced concrete wall is for avalanche protection and I would like to protect my building from a possible impact, I was considering to use a flexible connection between timber and reinforced concrete.

In any case, this is a project proposal, not a building I am building myself and without permissions. The appropriate experts will come at the right time, but I want to understand the problem to better design a solution. Thanks again for your time with the reply. I came across this old post and though you know well what you are talking about.

 

[PhanthomJay]

Laminated timber is a bit less strong than sawn timber of the same size, , but has its advantages in certain cases. Be aware of the possibility of the long term separation of the laminated layers, as i have seen this many times.

Simple support connections of wood beam to concrete columns is not a problem, using clip angles or shelf bolted to the wood and anchored into the concrete. I would be ver1y weary of a fixed wood bean to column of any material, since bolt holes in the wood tend to elongate after time and cause rotation at the ends. The simple support connection seems to meet your needs.