Welding Anchor bolts to base plate 1

[Bala0404]

Hi ALl,

I was confronted with a situation in the field. The contractor wants to cut the anchor bolts extending past the base plate and weld them to the base plate. I have never heard of this condition.
This base plate is carrying / supporting moment. Very little but has only 4 bolts.

Can any one suggest if welding is acceptable and if there are any AISC guidelines.

 

[KootK]

AISC design guide #1 deals with this stuff extensively and has some repair details. Usually something can be worked out.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Teguci]

Design guide 2 and 21 - Note, anchor rods may not be readily suitable for welding. Even ASTM A307 rods must bear S1 to verify suitable carbon content.

 

[MotorCity]

Welding anchor bolts to anchor bolts is one thing, but welding anchor bolts to a base plate is something completely different. Why does the contractor want to weld the anchor bolts to the baseplate?

Your anchor bolts and baseplate are most certainly not of the same grade of steel. As such, their carbon content probably varies significantly. The carbon content greatly influences weldability. Even if both are weldable, it does not necessarily mean that they can be welded to each other.

Then you have heat input. Each material will probably require a different amount of heat to achieve a sound weld to each material.

Now for the detail, what does that look like?

 

[BAretired]

Apart from welding issues, there is the loss of adjustment. A nut can be tightened, loosened or removed whereas a weld is permanent.

BA

 

[KootK]

A good link: Link. I'm no expert when it comes to weld procedures but, with the help of such an expert, I've had success welding almost anything to almost anything else. That said, often the contractor is deterred from the weld approach when they find out about just what needs to be done regarding the engagement of a specialist and preheat etc. I always hope for a nice F1554 grade 36 anchor bolt.

As others have noted, much will depend on what the detail is and the reasons for the contractor wanting to do this. If this is a situation where the connection is being proposed to be made using a plug weld over a short bolt, I wouldn't recommend that.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Bala0404]

Thank you all for your responses. Its an aesthetic issue. Tripping hazard. The side walk pavers top elevation is the same as base plate top elevation. So the blots are sticking up. Just for that reason.
The holes are 1/8" oversized. So I am not comfortable with welding. As kootK has suggested to use a heavy washer then its an option. But stll that plate washer sticks from the base plate and that we need additional length of bolt to do fillet weld.

I also got a response from a Portland bolt group. see below. still
************
If the anchor bolts are F1554 Grade 36 or Grade 55 S1, they can be welded to A36 or A572 Grade 50 plates. The chemistries of these products would allow it. From an engineering perspective, we do not have the expertise to know whether this welding will provide the anchoring strength you require.

Thanks,

Greg Lindsay
General Manager | Portland Bolt & Manufacturing Company
[p] 800.599.0565
[e] greg@portlandbolt.com
[w]

http://www.portlandbolt.com

********************************************

 

[MotorCity]

If there is very little column load and you have a wide flange column, you may want to consider new post installed anchors inside the column flanges. Then the bolts can project above the baseplate but should be out of the walking path.

 

[TehMightyEngineer]

Acorn cap nuts? What about pouring a little non-shrink grout over and around the base to cover up the nuts with a smooth slope?

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[Bala0404]

Unfortunately its an HSS column. Grout on top of anchor bolts may be a good thought. Let me run through the client.

Thanks again all.

 

[Ron]

TME....ya beat me to it! Grout

 

[KootK]

The holes are 1/8" oversized.

If that's true, 1/8" is nothing. Go ahead and weld it.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[nonplussed]

If the contractor doesn't want a tripping hazard, does that mean he will grind down the bold after or before welding to be flush with the plate? That would make the throat thickness indeterminable. Had this same situation come up on a project and it kept me up at night but that was for bolts in constant tension.