SAP2000_Design a RC slab using shell modelling

[plopez]

Hi:

I use Sap2000 to design RC elements but I don`t know how to use the Forces and Moments when my model of a slab is a shell.

I only use the output data to evaluate the displacements but I need design the reinforcement too.

Therefore , where I can get the tables of coefficients developed by Czerny to calculate moments in a traditional slab?

Thanks , I expect your answers......(sorry my English)

plopez

 

[edward1]

I use STAADPRO to model and analyze all kinds of concrete
slabs from bridge decks to retaining walls. After the analysis is finished, I go to post processing to get my forces on the elements(Mx, My, Qx, and Qy). From this I go
back and put the appropriate load factors on the particular loads and put in the appropriate concrete commands to design the concrete elements. STAADPRO will give you the required reinforcing steel for each element. I have to check the elements with another program to make sure the slab is thick enough for shear stress. This has worked well for me for 16 years at Virginia DOT.
Ed McFadden,P.E.

 

[stressed]

I haven't used Staad in a while, but one of my big complaints about it when using shell elements is that Staad only reports forces and stresses on a per shell basis -forces & moments are not available at each shell joint. If this is still the case, it is a big problem.

Forces could be zero on 2 joints and large forces on the other joints, but you would never know it, because you're only dealing with an average on a per plate basis.

Also, without joint forces, it's very difficult to get useful output results - base shear, for example. If Staad outputs required reinforcement on a per shell finite element basis, I'm not sure how useful that would be, since you would normally design based on strips.

With SAP2000, force and moments are reported at each shell joint, integrated over the shell thickness. Using SAP's group joint force sum option, I can get section cuts for strength design, or base shears using shell elements no problem.

SAP2000 will not do automatic calculation of required reinforcement for shells, only frames, but with joint reactions and the group joint force sum option, I can get section cuts to design slab reinforcement myself.

CSI has another product called SAFE which is specifically for design of concrete slabs as well as basemat foundations. SAFE will automatically design required reinforcement