concrete beam torional restraint

[Yorgen]

Hello.

i am currently design a massive 100/100cm beam monolitic connected by the top part to a 30 cm thick slab.

The beam experince certain torsion, But it is being restrained by the concrete slab which is capable of taking the torsion as concentrated moment at the edge.

My question:

does my logic sit well with your experience? is there any code referencing this force transfer?

when and if i model the slab as rotational spring support. what would be the equation concrete slab to rotational spring support (i assume its not even linear due to cracking)

 

[KootK]

What you are proposing is common practice. I believe that ACI refers to it as compatibility torsion. Exploring that concept should turn up any code requirements. In general terms, the procedure is:

1) Design the slab and the connection between the beam and slab to handle the conversion of the beam torsion into slab moment.

2) Design the beam, the beam supports, and the connection of the beam to its supports for the compatibility torsion which is a version of the torque that cracks the beam in torsion and facilitates load redistribution to the slab.

 

[Tomfh]

If the torsion arises solely due to the slab’s behavior (e.g., the rotation of its end support) and is not essential for the structural stability of the system, then, as Kootk suggested, it would be classified as “compatibility torsion.” Typically, such torsion requires some ties or reinforcement to prevent unsightly cracks from forming.

 

[lexpatrie]

The alternative is equilibrium torsion where the torsional resistance is needed for stability.