Modeling an Underground Groin Vault with Arched Walls for Analysis 1

[Struct_Dre]

Hello All!

Any help would be very appreciated. I need to analyze a 100+ year old underground structure with groin vaults and weird curved side walls. I originally tried modeling the structure in Revit and exporting it to RISA 3D, but only the columns show in the RISA model. So now I'm in the process of modelling the groin vaults and weird walls(see attached photos) and I would really like some advice on how to model this as accurately as possible. At this point, literature explaining how I can analyze the structure by hand seems easier, but I can't seem to find anything online.

Does anyone have any tips on how to model the groin vault easily and quickly? Most importantly, does anyone have any clue how I should model the walls???

PLEASE HELP lol

 

[Struct_Dre]

Hello All!

Just a follow up. I decided to simplify this and model the walls as circular arcs in RISA, but I'm not sure how accurate this will be.

 

[phamENG]

That's pretty neat.

Here's a thought: do the outer 3 bays by hand and see what kind of forces they transfer to the rest of the structure (I can envision a large surcharge along the edge creating an inward thrust) and then apply that to a model of the interior, which lends itself a bit more to RISA.

If you really want to model the whole thing, then I'd think drawing a midline through the curved wall to get coordinates and then breaking it up into an appropriate number of "levels". Vary the thickness of each "level" to be about the average thickness for that area of the wall. Be sure to fix the edges of the plates to one another. Then you can use the plate results to determine the reinforcement required and compare that to what is present.

 

[IDS]

I'd suggest starting with a 2D plane-strain analysis of the outer walls and surrounding soil and the first row of columns, including half the first internal span. Treat both edges of the model as fixed horizontally and free vertically. Use beam elements for the columns and arch slabs, factoring down the column stiffness to account for them not being continuous.

I have no idea if you can do that in Risa, but I think you need a package that can do that as a minimum, and also model soil non-linear behaviour.

I'd be interested to know where the structure is, if it's not confidential.


Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[Struct_Dre]

Thanks phamENG and IDS. I was able to model this in RISA close to its actual construction. It was quite a task to model the round elliptical arches with square plates, but it worked in the end! @IDS this is a reservoir in Baltimore, MD. Pretty cool structure