monchie
Structural
- Feb 22, 2011
- 96
Hello,
I was upset this morning for a simple reason that I cannot prove to myself that the self-wt of the thread of a stair is,THREAD(sw) = 1/2(R)25.
Assuming that the going/rise dimensions are 250mm/175mm respectively, and the wt. of concrete is 25 kN/m3, then, THREAD(sw) = 1/2(.175)(25) = 2.19 kN/m2.
If you have a waist thickness = 200mm, its self wt. is easily to comprehend,ie , WAIST(sw) = .20(25) = 5 kN/m2 because it is uniform thickness all the way, unlike the "thread".
Now, my personal assumption,is that, 1/2(R)(,ie,25), was formulated, in assuming, it is a slab with a 175mm thickness and it is simply divided in half,since the arrangement of thread is "alternate".
Is this correct? any proof will be greatly appreciated.
I was upset this morning for a simple reason that I cannot prove to myself that the self-wt of the thread of a stair is,THREAD(sw) = 1/2(R)25.
Assuming that the going/rise dimensions are 250mm/175mm respectively, and the wt. of concrete is 25 kN/m3, then, THREAD(sw) = 1/2(.175)(25) = 2.19 kN/m2.
If you have a waist thickness = 200mm, its self wt. is easily to comprehend,ie , WAIST(sw) = .20(25) = 5 kN/m2 because it is uniform thickness all the way, unlike the "thread".
Now, my personal assumption,is that, 1/2(R)(,ie,25), was formulated, in assuming, it is a slab with a 175mm thickness and it is simply divided in half,since the arrangement of thread is "alternate".
Is this correct? any proof will be greatly appreciated.
