Best quad mesh generation for SAP 1

[mgabrielle]

I am looking to find a good quad mesh generation software for SAP. We have a geometry model of a very complicated museum building from a laser scanning company. The building is a concrete shell structure and we will model it as shell elements. Because SAP doesn't have a full automatic mesh generation feature, we'd like other software to mesh and convert the model for SAP. Would you recommend the most appropriate mesh generation program for SAP? Any input would be greatly appreciated. For structural analysis, we don't want to switch to other software packages at this moment.

thanks in advance.

 

[GregLocock]

The only two automeshers I've used are FEMAP and Hypermesh. I'd guess that Hypermesh is more suitable, as its surface editing and geometry cleanup seems to be more comprehensive.

Sorry I don't know if it outputs SAP decks. Can SAP import any other decks?

FEMAP has an option to export mtab*STRESS SAP 386, whatever that means, but it is not installed in my version.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[dmacx]

FEMAP is easier to use and will be less expensive than Hypermesh but you are still looking at $7000 list.

 

[johnhors]

Roshaz has an automatic quad mesher plus good geometry clean up facilities. It can export a mesh in Abaqus, Lusas and Nastran formats (amongst others) but not in SAP. But then manually editing or even writing your own program to convert the format should be fairly straight forward.

 

[dozer]

Is there a mesh generation program for SAP?

 

[ThomasH]

As far as I know there is no mesher that is specifically written for SAP. However, I have read that SAP can import data decks from Nastran but I can't see it on their website anymore.

I tested it a while back and it wasn't very good but depending on your geometry it might help you. Ofcourse that means that you need some software to create the Nastran deck.

Just a thought.

Anyway, Good luck.

Thomas

 

[jackyyau]

I am looking for guidlines on how to design the RC shells with SAP2000 shell element analyses output forces.

It is noted that the resultant forces (M11, M22,M12, V11, V22, F11, F22 etc) from SAP analyses cannot be used directly for RC design in accordance with the design codes.

 

[mgabrielle]

Here is a response from the the SAP2000 tech. support team:

The official documentation for concrete shell design implementation in SAP2000 is still under development and should be available soon. Meanwhile, here is some interim information on concrete shell design to keep you going.

The design of reinforcement for concrete shells in accordance with a predetermined field of moments, as implemented in SAP2000, is based on the following two papers:

Optimum design of reinforced concrete shells and slabs” by Troels Brondum-Nielsen, Technical University of Denmark, Report NR.R 1974
Design of Concrete Slabs for Transverse Shear”, Peter Marti, ACI Structural Journal, March-April 1990
Generally, the slab elements are subjected to eight stress resultants. In the SAP2000 terminology, these are: the three membrane force components F11, F22, and F12; the two flexural moment components M11, M22, and the twisting moment M12; the two transverse shear force components V13, and V23. For the purpose of design, the slab is conceived as comprising two outer layers centered on the mid-planes of the outer reinforcement layers and an uncracked core (this is sometimes called a "sandwich model"). The covers of the sandwich model (i.e. the outer layers) are assumed to carry moments and membrane forces while the transverse shear forces are assigned to the core. The design implementation in SAP2000 assumes that there are no diagonal cracks in the core. In such a case, a state of pure shear developes within the core, and hence the transverse shear force at a section has no effect on the in-plane forces in the sandwich covers. Thus, no transverse reinforcement needs to be provided, and the in-plane reinforcement is not enhanced to account for transverse shear.

Given below is a summary of the procedure as implemented in SAP2000:

1. As mentioned above, the slab is conceived as comprising two outer layers centered on the mid planes of the outer reinforcement layers

2. The thickness of each layer is taken as equal to the lesser of:

- twice the cover measured to the center of the outer reinforcement

- twice the distance from the center of the slab to the center of outer reinforcement

3. The six resultants F11, F22, F12, M11, M22, and M22 are resolved into pure membrane forces N11, N22, and N12 calculated as acting respectively within the central plane of the top and bottom reinforcement layers. In transforming the moments into forces, the

lever arm is taken as the distance between the outer reinforcement layers.

4. For each layer, the reinforcement NDes1, NDes2, concrete principal compressive forces Fc1, Fc2, and concrete principal compressive stresses Sc1 and Sc2, are calculated according to the rules set out in Reference 1 above.

5. Reinforcement forces are converted to areas per unit width (i.e. reinforcement intensities) Ast1, and Ast2 using appropriate steel stress and stress reduction factor.

You can use this feature to estimate the reinforcement requirements for a concrete shell element used in any model. As is evident from the above discussions, the design is solely based on element stress resultants obtained from a finite element analysis. No effect of the boundary conditions is directly used in the design routines.