Mis-placed base plate

[SperlingPE]

When a base plate is set in the wrong spot, is there any concern about leaving the anchor rods in the concrete and setting adhesive/epoxy anchors next to them. Do the cut-off anchor rods affect the capacity of the new rods?

 

[Lutfi]

I would cut off the anchor bolts and leave them in place. I see no harm in leaving them in the concrete.

Check the footing due to new eccentricity if the column location is shifted. Another concern, if the base plate and footing will be exposed to weather, make sure you treat the exposed portion of the AB with good rust inhibitor or may be tar or great so that rust does not bleed off on the concrete.

Regards,

 

[SperlingPE]

Most adhesive/epoxy anchors require you to take a reduction in capacity for spacing between the anchors. Now you have an embedded rod near the new anchor. What is the reasoning for not being concerned with the embedded anchor near a new adhesive/epoxy anchor?

 

[blake989]

The embeded rod has been cut off, it is not loaded, and it does not load the concrete. It is just a really big piece of aggregate in the concrete now. The reason why you reduce capacities for spacing is that a shear cone will develope around the rod in the concrete. This cone typically forms at a 45 degree angle from the head of the stud to the free surface. Example, if you have a stud embeded in the conrete 6" with an applied tension load, a shear cone developes. If there are any more studs within a 6" raduis of this stud, their tension cones will overlap. Hence a reduction in capacity for spacing and edge conditons.

 

[MotorCity]

Determine if the failure cones of the anchor rods overlap. If they do, they should be relocated so that they do not overlap. The failure cone concept assumes a homogenous material (Mohr circle) and consequently the failure surface takes the shape of a cone. If you introduce a foreign object, such as an anchor rod, into the cone the failure surface will be different as it will follow the path of least resistance. If the failure cones do not overlap, I would do as Lutfi suggested and waterproof them.
Good luck.

 

[Ron]

The impingement of the shear cone is an unknown, so I would look at taking a reduction, similar to the spacing reduction. Without test results, you don't know if the impingement increases or decreases the capacity of a promimate anchor.

 

[Ibeam]

I had a misplaced base plate not too long ago and I did the following:
1. welded a plate extension on to pick up 2 cast-in-place anchors that fell outside the plate. Used a gusset to strengthen the new addition.
2. burned 2 new holes in the original plate to pick up the other 2 anchors.
3. drilled and sunk Hilti epoxy anchors into 2 of the existing holes to restore some concentricity to the connection.

I'd agree with blake989, if they're not loaded, it's just a piece of metal aggregate. There's a bond strength between the paste and the anchor. But I can sort of see how it might depend on HOW Close you're talking about, when setting the new next to the old.