We will be doing an anchor bolt asbuilt on an ongoing project. I inspected the bolts this morning and found that the majority are not even close to plumb. We are looking to asbulit the center of each bolt at the base where the plate will sit. I am always looking for a better way and would like to hear how others tackle this.
Hack
Wrap a plumb bob string around them diagonally so it crosses itself at the center or the pattern. Or use large rubber bands to do the same thing. Be careful to get the string all the way down where the bolts come out of the concrete.
Dan Patterson, post: 333385, member: 1179 wrote: Wrap a plumb bob string around them diagonally so it crosses itself at the center or the pattern. Or use large rubber bands to do the same thing. Be careful to get the string all the way down where the bolts come out of the concrete.
Sorry Dan I wasn't clear ( since edited). We are looking for the center of each bolt.
Hack, post: 333386, member: 708 wrote: Sorry Dan I wasn't clear ( since edited). We are looking for the center of each bolt.
Are you sure that is the correct scope of your services? Dan's method is the most logical and what I have done in the past.
in this case, traditional and elementary is best
measure from offsetting control lines, such as 3 feet offset grid, each way. use a plumb bob and ruler, if necessary. compensate for half the thickness of the anchor bolt.
make a sketch per anchor bolt pattern type and write the as built values into that. now you have a check of each bolt's location and an indication of the setting/squareness of the bolt pattern as a whole
Why each bolt? The only benefit I see to that is to show possible pattern rotation, but that can usually be observed visually looking down the line of patterns (depends on the specific situation though).
Can you mark the centers as I described and measure over to the bolts from the determined column line? You can't really shoot them directly if they're as bent as you say.
Hack, post: 333381, member: 708 wrote: We will be doing an anchor bolt asbuilt on an ongoing project. I inspected the bolts this morning and found that the majority are not even close to plumb. We are looking to asbulit the center of each bolt at the base where the plate will sit. I am always looking for a better way and would like to hear how others tackle this.
Hack
I'm not sure thats really possible unless you saw all the bolts off about 1/4" above the concrete...
I believe Moes method is the most accurate. I would also set the nuts at finish grade as well and locate the bolts at the top of the nut. The steel guys will typically shim to the nut to set their plates. You need to locate all the bolts to show if the pattern is twisted.
Jhowes, post: 333411, member: 10180 wrote: I believe Moes method is the most accurate. I would also set the nuts at finish grade as well and locate the bolts at the top of the nut. The steel guys will typically shim to the nut to set their plates. You need to locate all the bolts to show if the pattern is twisted.
Okay...who is Moe and what is his method?
Hack, post: 333413, member: 708 wrote: Okay...who is Moe and what is his method?
see above:
"in this case, traditional and elementary is best
measure from offsetting control lines, such as 3 feet offset grid, each way. use a plumb bob and ruler, if necessary. compensate for half the thickness of the anchor bolt.
make a sketch per anchor bolt pattern type and write the as built values into that. now you have a check of each bolt's location and an indication of the setting/squareness of the bolt pattern as a whole "
Dan Patterson, post: 333415, member: 1179 wrote: see above:
"in this case, traditional and elementary is best
measure from offsetting control lines, such as 3 feet offset grid, each way. use a plumb bob and ruler, if necessary. compensate for half the thickness of the anchor bolt.
make a sketch per anchor bolt pattern type and write the as built values into that. now you have a check of each bolt's location and an indication of the setting/squareness of the bolt pattern as a whole "
Thanks Dan
Hack, post: 333413, member: 708 wrote: Okay...who is Moe and what is his method?
Moe Shetty had previously replied to your post. He discusses measuring directly off your grid lines.
I've never seen a crew allow anchor bolts noticeably out of plumb. Guess I'm spoiled. Are these on pile caps for precast columns?
It's usually the result of the combination of a conflict with the gobs of re-bar that the engineer required and a rush pour.
Have the contractor first plumb the bolts with bar. I use string line wrapped at oppoiste bolts to creat bolt pattern center at approximate height of base plates. I locate top of SE bolt to provide elevation of base plate adjustments to client. I will also measure top of each bolt only to confirm orientation of pattern. I don't center each bolt. Not needed. Contractors can bend bolts, or drill and core new ones. Also I have been able to send measurement fom grid centers to steel shop for them to move plates. They do not want a drawing for each bolt. Just the center of bolt pattern relative to the grid lines.
On some jobs yes. When the bolt is 2.5 inch diameter with 6 inches exposed I can't see it getting straight without destructive force. Lots of unanswered questions..
thebionicman, post: 333423, member: 8136 wrote: I've never seen a crew allow anchor bolts noticeably out of plumb. Guess I'm spoiled. Are these on pile caps for precast columns?
Yes they are.
Jhowes, post: 333417, member: 10180 wrote: Moe Shetty had previously replied to your post. He discusses measuring directly off your grid lines.
I liked "Moes Method" better than Moe's method. it seemed to have more of a scientific bent.
Here is a sample sheet of anchor bolt verification from reference to grid lines. This job was very easy. They were using steel level plates, which already had a center dipple punch in them.
If you must locate center of each bolt, there was a jig sold by www.loink.com (very expensive like $200å±). I just searched for it, but can't find it at there site. I have seen some surveyors make their own jig.
Thanks all. Just heard back from the Project Engineer and he has backtracked and will accept the center of the bolt pattern.
Hack