Concrete beam to concrete wall fixity

[ChiEngr]

Hello,

I am designing a strut between two retaining wall structures for reasons I won't get into in this post. My question is the following: The beam end will have some fixity at the wall interface. However, I am wondering if a conventionally reinforced wall will be able to resist that moment. I thought of a simple strut and tie model, and I am convinced that I would need tension ties between my sets of vertical wall bars in order to resist the transverse tension forces up the height of the wall. Am I making any sense, or am I complicating the issue at hand?

 

[HTURKAK]

At least a sketch would help to visualize your case. You may detail the connection to minimize the moment transfer if this is the concern.
If this is new construction, you may design the wall and choose the reinf. considering the strut .
..

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[ChiEngr]

HTURKAK,

Here is a sketch of my condition/connection. I am wondering if the negative moment can be transferred into the wall with the reinforcing layout shown. That is what I am debating.

 

[HTURKAK]

- You need to calculate to see if the negative moment can be transferred into the wall ,
- If you want to avoid moment transfer , you may design the conn. as simple conn. Say , the beam is supported on corbels..
..

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[JAE]

First (prior to your question) the amount of moment coming into the wall would depend a lot on the relative stiffness of the wall with respect to the beam and the rest of your structure.
Imagine a thin, wispy wall - very flexible - won't attract much load and the beam would "think" its a pinned end.
Alternatively, think of a very thick, 10 ft. wall. It would almost act like a fixed end.
Your wall/beam condition is somewhere in between.

Second - yes the beam can be designed to be fixed into the wall depending on whether you can develop the beam bar hooks - i.e. is the wall thick enough to allow that.

Finally - I'm not sure I would use a strut and tie here - simply assume an effective width of wall that can take the bending.
I would probably assume a very narrow wall width just to be conservative (i.e. band some vertical wall bars in close proximity to the beam as required to take the amount of moment that actually gets int the wall (my first point above).

 

[Greenalleycat]

Definitely can/will transfer some moment with that setup.
You could do a 3D model and guesstimate how significant this moment is

Alternatively, you could detail the beam differently to mitigate the issue
How much load is going down the strut?

 

[ChiEngr]

@JAE and @Greenalleycat,

Thanks for your responses. I ended up enveloping the solution and analyzed the strut as being pinned-pinned as well. I probably will end up concentrating some additional vertical bars in the wall over a 2'-0" width where my strut comes in. I also used a smaller bar size to ensure ldh meets the code required development value.