Concrete Slab Design using STAAD (Polygonal Meshing)

[Rainbowtrout]

Hi All,

(This post is moved from Structural engineering other technical topics Forum: thread507-364507)

I have a concrete roof slab with a few circular openings and rectangular openings, and it is framed into concrete walls on all sides. The roof slab needs to be designed for HS-20 (highway truck) loads. I am using Polygonal Meshing in STAAD to create triangular plate elements.

Question:
1) Has anyone used the Global Moment outputs given in STAAD? I couldn't find any documentation on how its calculated, and whether it follows the Wood-Armer formula (add Mxy to Mx and My). If you don't use global moments, how do you design orthogonal reinforcement? Keep in mind triangular plates have their local axes all over the place.

2) Do you typically use plate center stress or plate corner stress? I usually use plate center stress. I think plate corner stress can be over conservative and there is no need to design for the moment occurring at the exact centerline intersections. However, this post (

http://communities.bentley.com/products/structural...)

makes think twice. What do you use and what is your reasoning?

Thanks!

 

[edward1]

I use STAAD PRO to design reinforced concrete tanks, bridges, and box culverts. I use plate elements to model these in 3 dimensions the program. The program gives Mx , My with the area rebar in in^2/ft of width in both directions. I have had good results with actual tanks, bridges, and box culverts that were built with these designs.

 

[Rainbowtrout]

Thanks edward1. I was more interested in irregular shapes. I got some interesting posts on the same topic in another forum section. See thread507-364507 if you are interested.