Slab Design

[saleem khan]

Assalam-o-Alikum everyone,

if moment contour for slab is available after analysis of slab in csi safe,for designing this slab safe will calculate reinforcements for every slab element i-e mesh element after that how i will distribute these reinforcements throught the slab because bending moment varies from one slab element to other.

[UmarMakhzumi]

SAFE does provides you with reinforcement design out put for slab that you can use. You can also look at the moment contours and design for the maximum moment in the slab. If the moment gradient is significant, you can divide your slab in zones and provide reinforcement in each zone accordingly.  

 

Thanks.

[saleem khan]

if i use parallel and perpendicular strips throught the slab irrespective of the position of columns,beams,walls etc and then distribute reinforcements in that strips what you think about this.

[UmarMakhzumi]

I don't think its a good idea.  Define your strips they way they should be- Column and Middle

[EngrUzair]

Assalam-o-alaikum!

 

Here are my 2 cents:

 

If you have rectangular panels, having supports (walls, beams, columns) along the edges, the best and recommended way is to provide reinforcement in standard design strips - Column strips 7 Middle Strips (defined in ACI 318-05 Section 13.2).

 

In SAFE software, slab reinforcement is also distributed in the form of Design Strips, subdivided into Column Strips and Middle Strips. Column strips are detailed for the required negative reinforcement, and the middle strips, for the required positive reinforcement.

 

For rectangular slab panels, width of column strips is taken as 'span/4' of the two slab spans on either side of support (beam etc) for interior slabs, and  'sum of span/4 for exterior slab span, & the  width of shade or cantilever portion' for exterior spans.

 

In SAFE, each slab panel is subdivided into column and middle strips along both horizontal slab axes (namely, X and Y directions). Widths of various column and middle strips may be checked (and modified, if needed), using specific menu commands. For example, in order to check/modify X-direction design strips, following steps may be used (for SAFE version 8):

 

1. Go to  'View' -> 'Set X-strip layer' 

2. Right-click on the strip to be checked/modified. 'X Design strip' options window will appear.

3. Modify the strip dimensions, if needed.

4. Press OK to make the changes effective.

 

Process for the Y-strip layer is similar, except that 'Set Y-strip layer' option is to be selected in step-1.

 

In case the supports are irregularly located, it is still possible to define design strips. For this purpose reference may be made to the following thread:

 

http://www.sepakistan.com/topic/1635-design-strips-in-safe/

 

 

Regards.

 

 

[WR1]

Middle strip, column strip is for manual design. You can use the same in SAFE.

 

But you can also draw unit width strips in x and y directions irrespective of column locations and put reinforcement according to that. At the end FE results from SAFE show you stress results and you have to satisfy that with reinforcement. Its not compulsory to draw strips as just column and middle strips.

 

In SAFE a design strip can be of any width, usually 1m/1ft wide