Post Tensioned Concrete
Post Tensioned Concrete
(OP)
Hi:
I am relatively new to the design of pre stressed concrete (studied way long).What I want know is, that when checking for ultimate limit state, the applied moments are specifies as "secondary moments + factored dead&live load moments".These are compared with the section moment capacity.What I want to know is that why these SECONDARY MOMENTS/HYPER STATIC are treated as external moments?
Please help!!
I am relatively new to the design of pre stressed concrete (studied way long).What I want know is, that when checking for ultimate limit state, the applied moments are specifies as "secondary moments + factored dead&live load moments".These are compared with the section moment capacity.What I want to know is that why these SECONDARY MOMENTS/HYPER STATIC are treated as external moments?
Please help!!






RE: Post Tensioned Concrete
The internal primary moments are not considered at the ultimate limit state (ULS) since you're checking the section at it's ultimate capacity irregardless of loading or prestress. Since the sectional stresses at ULS are taken at their ultimate value, maximum concrete strain and near yield in the tendon, any additional stress caused by internal prestress is irrelevant. Also in this state the concrete around the tendon is cracked, and therefore the prestress is generally considered to be overcome. Don't think about this too hard since it is a theoretical simplification.
RE: Post Tensioned Concrete
RE: Post Tensioned Concrete
The primary moments do not result in any support reactions and hence are not treated as external moments.Right?
RE: Post Tensioned Concrete