Real World Examples of Beams with Free Ends and Restrained Ends

[dwf123]

Greetings All

My first post so I hope I'm in the right place.

I am designing a beam for my own domestic extension and am trying to understand when a beam should be classed as free or restrained from rotation at the supports and what can be done physically to create a restrained beam. Perhaps a few examples might help me understand:

A beam in a joist hanger that has been installed correctly (ie all nail locations have been filled) - free or restrained? I assume free if was being designed?

A first floor joist sitting on a timber frame (ground floor) but then sandwiched by the first floor wall being placed on top of said joist? I would assume this would be restrained?

A beam built into a solid wall - I would assume this should be designed as restrained?

And in my case an oak beam that would be simply supported onto a concrete wall (supporting roof joists above) - which I know would be designed as free. However - if I design this beam to be bolted into the concrete wall (design of the bolt/holding down arrangment etc dependent) - would it then be appropriate to call this a restrained end for the purpose of designing the beam?

Thoughts and ideas much appreciated.
D

 

[dik]

I'd normally treat this as unrestrained, but check to see the effects of any moment on a wall. To prevent restraint, old constuction often had floor joists that were 'firecut' to prevent rotational restaint.


I'd also treat this as free to rotate. With highrise construction I generally treat slabs that are cast into stair/elevator shafts as restrained, and if at a corner I often treat it as fixed... many engineers don't.

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

-Dik

 

[kipfoot]

As I interpret your question, you're asking whether the support condition is pinned or fixed. I'd say all your examples are pinned (i.e. minimally restrained against rotation at the support)

 

[rb1957]

if you want to be conservative then consider the beam having pinned ends when you're designing the beam section, and fixed ends when designing the supports.

another day in paradise, or is paradise one day closer ?

 

[HouseBoy]

I too would consider all of the conditions you described as pinned.
As dik wrote, the "connection" must be capable of developing the moment.
Even in the case of the beam built into the wall for example, it seems unlikely that the amount of embedment into a wall would be broad enough for the moment to be developed.