Anchorage of mechanical equipment to slab.
Anchorage of mechanical equipment to slab.
(OP)
I have some mechanical equip. on a 9th story and Im designing the anchorage of the equip to the slab. The manufacturer provided anchorage locations (see attached drawing) are pretty far in from the edges of the equipment, which results in very large uplift forces if one assumes that these are the bearing points. How can use the obvious bearing of the equipment against the slab to help me reduce these large values? I can see in theory that there will be plenty of overturning resistance provided here, but Im unclear on how to calc such a thing. Is there a "safe" amount of equipment bearing area that I can assume helps me??






RE: Anchorage of mechanical equipment to slab.
RE: Anchorage of mechanical equipment to slab.
RE: Anchorage of mechanical equipment to slab.
I will gladly attach an overturning calc for you. What building code... and what is your Sds and Ip. And you said 9th story.. how many stories total?
RE: Anchorage of mechanical equipment to slab.
RE: Anchorage of mechanical equipment to slab.
Why not talk with the equip. manufacturer’s engineering dept. Half of those hold down designs were/are to prevent the equip. from vibrating across the floor and may not have been changed to reflect our greater concern for EQ loadings. It would seem that you could double your lever arm to the tension bolts, but you have to know what the sub-frame of the equip. looks like to make this determination. Maybe the shop drawing show some of this info., they should show a max. bolt load for their arrangement. You may want to shim or grout btwn. the sub-frame and the slab so you do know where the bearing points are.
RE: Anchorage of mechanical equipment to slab.
RE: Anchorage of mechanical equipment to slab.
I've just been working out some concrete loading based some machine frames with loads high above the bolt positions and without much information to go on, so like WannabeSE suggests we used one bolt centre as the pivot and the other as resisting the tension generated by the overturning moment, so we ignore the contribution from the bolts nearest the pivot point.
This assumes that the machine frame is ridged however and in our case it's probably a fair assumption, this might not be the case in your situation.
RE: Anchorage of mechanical equipment to slab.
http://vietcons.com/uploaded/download/AISC-T-DG01-...
RE: Anchorage of mechanical equipment to slab.
I am envisioning tension on the anchor at C and a triangular distribution of compression from 0 at C to maximum at A, giving you a moment arm of the distance from C to AC/3.