Anyone know how to model an expansion joint of suspended concrete slab in Etabs ? 1

[Huong83]

This expansion joint don't transfer bending moment. Or simply, one edge of a RC slab sit on an edge of other RC slab.

Thanks.

 

[MrHershey]

My end result would be two separate models. If joint is at a column line, you'd model columns on both models and then apply a line load or joint load(s) as appropriate at the expansion line for the support side.

If you're just starting out, would model everything in one model, do a save as to have two copies of the same model. And then delete structure on either side to get to two different models and then apply loads as described above.

 

[asixth]

I think separate models as well. If it is a true expansion joint and there is no transfer of lateral forces than both sides of the building joint will have individual responses.

 

[Huong83]

Yeah, That is the only way I did. Break up the model into 2 models.
One model with pin supports along the expansion joint. Obtain the reactions of this model, then apply these loads to the other model.

I don't think Etabs having any function for you to have an expansion joint in one model.
Thanks.

 

[MrHershey]

They're intended to function as two separate buildings, so they wouldn't really need one. Only thing I can think of would be a link between two joints that that locks vertical displacement between the two joints and only vertical displacement. But I don't believe the difference in results between that and just two different models would be that large. And would increase your run time since ETABS is analyzing and designing two different buildings at once.

Would think the convenience and efficiency of having two separate models would trump any marginal increase in accuracy of having one.

 

[Huong83]

I am not sure if you can use the link in Etabs. The link will give no moment along the expansion joints.

 

[MrHershey]

Typically I wouldn't consider moment around the expansion joint. If the supported slab is sitting on resilient bearing pads that allow lateral movement like typically occurs at expansion joints, then there would be no way to transfer the moment anyways.

Specifically designing and detailing for moment transfer would kind of destroy the point of having an expansion joint in my opinion. Not even sure how you'd do that with a concrete slab without allowing the slab to undergo lateral deformation independently on each side of the joint.

 

[Huong83]

Of course, the expansion joint have no moment. I mean here to use the link to be modelled as an expansion. The link just like a beam without property and no torsion moment.

For separate models, Use vertical pin support only so you can have lateral displacement.