Two small questions please HELP!!!
Two small questions please HELP!!!
(OP)
Hi, Just a few questions:
1. For a singly reinforced concrete beam, why is a minimum percentage area (100As/bh) of tensile reinforcement required?
2. Why is the maximum value of the lever arm (la = z/d) limited to 0.95?
Thanks.
1. For a singly reinforced concrete beam, why is a minimum percentage area (100As/bh) of tensile reinforcement required?
2. Why is the maximum value of the lever arm (la = z/d) limited to 0.95?
Thanks.





RE: Two small questions please HELP!!!
I'm not sure where you are getting the limit for la. Is this a working stress design?
RE: Two small questions please HELP!!!
I am unfamiliar with the .95d limitation, but it could be related to the same thing, as most well designed beams will have enough steel so that the lever arm is closer to .85d.
RE: Two small questions please HELP!!!
Regarding the lever arm depth, i seem to have found something that suggests it is because of two reasons;
1. As this is very close to the suface of the beam, steel is likely to fail as it will have very high strain
2. Concrete is weaker here due to higher water content from travelling off (Laitance Curing Effect)??
Could any of these be a valid reason?
RE: Two small questions please HELP!!!
RE: Two small questions please HELP!!!
Lever arm z=d(0.5+√(0.25-(K/0.9)) but not greater than 0.95d.
RE: Two small questions please HELP!!!