bugbus
Structural
- Aug 14, 2018
- 504
Can the spiral reinforcement provided behind a post-tensioning anchorage (i.e. in the local zone of the anchorage) be assumed to contribute to the requirement for reinforcement in the general zone? I use the terms local and general as they are used in AASHTO and other places, see picture.
My understanding is that the spiral is mainly intended to provide confinement to the concrete directly behind the bearing plate and thus enhance its bearing capacity.
Whereas the general zone reinforcement is intended to control any potential splitting cracks along the axis if the tendon.
Can the same reinforcement be used to achieve both? Or would this doubling up effectively over-stress the reinforcement, which would normally be designed for a stress of 150~200 MPa under jacking forces?
I imagine that if the local zone is much smaller than the general zone (e.g. for a wide element), the spiral reinforcement simply would not cover enough of the general zone to be effective. But for a narrow element (e.g. beam web), where the size of the anchorage is relatively large, a spiral of sufficient proportions could potentially carry out both functions.
My understanding is that the spiral is mainly intended to provide confinement to the concrete directly behind the bearing plate and thus enhance its bearing capacity.
Whereas the general zone reinforcement is intended to control any potential splitting cracks along the axis if the tendon.
Can the same reinforcement be used to achieve both? Or would this doubling up effectively over-stress the reinforcement, which would normally be designed for a stress of 150~200 MPa under jacking forces?
I imagine that if the local zone is much smaller than the general zone (e.g. for a wide element), the spiral reinforcement simply would not cover enough of the general zone to be effective. But for a narrow element (e.g. beam web), where the size of the anchorage is relatively large, a spiral of sufficient proportions could potentially carry out both functions.
