Underground Water Tank Analysis using STAAD - query on support condition

[ak.t]

Hi all,

How to define appropriate supports for the precast panel water tanks in Staad model? Snapshot from Staad model below shows the support defined in model. Wall unit considered as monolithic. Is this the right approach?

The precast side wall panels are stitched with cast-in-situ RC (sketches posted below) to form a single long wall unit.
Appreciate guidelines/ input/ opinion of yours. Thank you.

 

[WARose]

As far as the supports go.....I don't understand why you (appear) to have some sort of lateral restraint at the top of the wall. Is this meant to represent the slab on top? Seems to me like you would just model the element itself.

You are not (as far as I can tell) assigning any lateral restraint where the slab is in contact with the ground. (To represent sliding friction resistance.) I would.

 

[MotorCity]

If these are precast panels, why do you consider them monolithic?

In general, monolithic construction = fixed, precast = pinned......of course, that depends greatly on how the connections are detailed.

 

[ak.t]

@WARose, Yes it is to represent the slab on top. It is hollowcore with topping that tied in to precast wall panels.

@MotorCity, Yes, the precast panels are sticthed together with cast-in situ concrete pour. Details are shown in above sketch.
Two precast panels are stitched together to form a single unit to achieve the desired length of the wall. But still i wanna confirm..

 

[Sye123]

PLATE MAT DIR Y with compression only attribute would be adequate for the bottom.

 

[ak.t]

Sye123,

Okay. But my concern is about the walls there. Two precast panels are stitched together to form a single unit to achieve the desired length of the wall.