column strip widths - direct design method - limit to drop widths for negative moment design????
column strip widths - direct design method - limit to drop widths for negative moment design????
(OP)
I have a flat slab with 8'x8' drops. The column spacing is 30'x20' If I follow the CRSI examples in chapter 10, they use a column strip width equal to the lesser of l1/2 and l2/2. If I follow this, I will have a column strip width of 10', which is greater than my drop width. I was thinking that I would need to limit my column strip width to 8' when considering the negative moment reinforcing (located in the top of the slab at the supports). Otherwise, how could I use the d that I get from the total drop thickness outside of the limits of the drop where the slab is thinner? This is exactly what CRSI uses.....a column strip that is wider than the drop, but also uses the greater "d" dimension that only occurs at the drop. This is puzzling to me.






RE: column strip widths - direct design method - limit to drop widths for negative moment design????
1. The larger "d"
2. The full column strip width (for As determination)
3. The drop width for your compression block width.
RE: column strip widths - direct design method - limit to drop widths for negative moment design????
Here is an example. Example 2 starting on slide 40 follows the same method as CRSI.
http://www.powershow.com/view/a095c-YTBiO/Lecture_...
RE: column strip widths - direct design method - limit to drop widths for negative moment design????
BA
RE: column strip widths - direct design method - limit to drop widths for negative moment design????
Dik
RE: column strip widths - direct design method - limit to drop widths for negative moment design????
Yes, that is correct.
RE: column strip widths - direct design method - limit to drop widths for negative moment design????
British code actually requires that the column strip width is the same as the drop panel width, but the momeent in the column strip is reduced to match the reduced width. I do not think this is logical and use of the normal column strip width with the full column strip moment is logical as long as the column strip width rules are followed.