Cable Tension Tie for Preengineered Metal Building
Cable Tension Tie for Preengineered Metal Building
(OP)
I have done a lot of foundation designs for preengineered metal buildings, but our client has requested something I have not heard of before. I designed a tension tie through the slab-on-grade using #6 bars (the thrust at the column bases was too large for hairpins). The client wants me to consider using a CABLE instead. How is the connection to the pier done? Does the cable need concrete protection, or can it be buried under the slab-on-grade?
DaveAtkins






RE: Cable Tension Tie for Preengineered Metal Building
RE: Cable Tension Tie for Preengineered Metal Building
DaveAtkins
RE: Cable Tension Tie for Preengineered Metal Building
I would use the cable and would sleeve it in a pvc pipe to keep it from bonding and transmitting loads to other structural members (i.e slabs).
Regarding the end, be creating as long as the connection can take the tensile and any bending. Check on the pier and footing for new induced possible overturning moment and the soil bearing pressure as well.
Good luck
RE: Cable Tension Tie for Preengineered Metal Building
Remember, for the strand to carry the load it must stretch. You can let it stretch when the load is applied or you can pre-stress the tendon. If you let a long strand stretch (PL/AE) when the load building load develops, you could get significant structure movement. This can also happen with other types of cross ties such as threadbars and coupled rebars. If you pre-stress the strands, you will be pulling on the bases of the columns with nothing to prevent inward lateral column movement except the backfill around the columns. If, in the future, there is a need to excavate inside the building for other construction such as a new pit, foundation, or utility, the tied, opposing columns could possibly move toward each other when the restraining dirt is excavated.
Sometimes, you just can't use hairpins.
RE: Cable Tension Tie for Preengineered Metal Building
RE: Cable Tension Tie for Preengineered Metal Building
The problem of corrosion of the strands that make up the wire rope or prestress strand is a critical one. A few wires can corrode pretty quickly compared to a solid rebar or rod, with really bad consequences.
And, you can always design the column piers and footings to take the applied moment of the horizontal thrust, but it leads to big footings. But, it does solve the problem of future remodeling that may cut the ties between columns.
RE: Cable Tension Tie for Preengineered Metal Building
See www.langtendons.com for additional information.