jwkilgore
Structural
- Feb 27, 2003
- 27
Both ACI 318-11 and -14 require that the ends of independent circular ties terminate in standard hooks. This is a significant change from the old lap terminations.
I work in the power transmission industry, and standard footing designs are typically circular drilled piers. For large engineered poles, typically there is a standard outer circular reinforcing cage with a long internal anchor bolt "cage" at the top (usually made of threaded #18J bars on the order of 10-ft long). This cage will typically have templates of steel rings at the top middle and bottom instead of ties. For the past several years the clients I've been working with have used spiral ties for circular concrete piers. The design is based on standard tie strength parameters, so the spacing is the wider tie spacing.
Now I'm transitioning to clients who use independent ties, and I'm getting pushback on requiring the hooks at each end. I've seen drawings issued very recently with the old lap splices, using the old "but we've always done it that way" argument.
The problem is that the hooks interfere with the anchor rods. The AR template is usually 3" clear from center of bolt circle to edge of template. This, plus allowing for the hook (even a 180° hook), is pushing the concrete diameters up a size from what they are used to.
My solution is to go to spirals designed as ties (quicker, cheaper, etc.) But again, "we've never done it that way".
Just for clarification, does anyone know of any exception in ACI 381-14 to allow for the old lap splice designs for in-ground circular piers in a non-seismic area?
To further complicate the issue, these structures usually aren't required to meet IBC requirements. They are designed to IEEE C2 (National Electric Safety Code), which literally states "Foundations, settings and guy anchors shall be designed or be determined by experience to withstand the loads in [list of load tables]..." and that's it. But the current "standard of care" is the ACI 318, and I'm really hesitant about not following it.
I work in the power transmission industry, and standard footing designs are typically circular drilled piers. For large engineered poles, typically there is a standard outer circular reinforcing cage with a long internal anchor bolt "cage" at the top (usually made of threaded #18J bars on the order of 10-ft long). This cage will typically have templates of steel rings at the top middle and bottom instead of ties. For the past several years the clients I've been working with have used spiral ties for circular concrete piers. The design is based on standard tie strength parameters, so the spacing is the wider tie spacing.
Now I'm transitioning to clients who use independent ties, and I'm getting pushback on requiring the hooks at each end. I've seen drawings issued very recently with the old lap splices, using the old "but we've always done it that way" argument.
The problem is that the hooks interfere with the anchor rods. The AR template is usually 3" clear from center of bolt circle to edge of template. This, plus allowing for the hook (even a 180° hook), is pushing the concrete diameters up a size from what they are used to.
My solution is to go to spirals designed as ties (quicker, cheaper, etc.) But again, "we've never done it that way".
Just for clarification, does anyone know of any exception in ACI 381-14 to allow for the old lap splice designs for in-ground circular piers in a non-seismic area?
To further complicate the issue, these structures usually aren't required to meet IBC requirements. They are designed to IEEE C2 (National Electric Safety Code), which literally states "Foundations, settings and guy anchors shall be designed or be determined by experience to withstand the loads in [list of load tables]..." and that's it. But the current "standard of care" is the ACI 318, and I'm really hesitant about not following it.
