huangyhg

anchor bolt sleeve
hello,
fan manufacture drawing shows anchor bolt with sleeve. my question is, what is the reason to provide sleeve?
thanks,
is this a proprietary chemical anchor with a cavity sleeve or is this a through bolt with a steel pipe sleeve?
csd
its a through bolt with steel pipe sleeve and bolt is j-type
j type bolts are not good in tension, but the steel indicates a pretensioning of the bolt.
does it means steel fails first before the concrete cracks???
no, the j bolt has the inner curve concrete crush and then fail. steel yield/failure is desirable as it is ductile and as a weak spot or strength fuse.
the purpose of the sleeve is to provide a longer free length of stud to be stretched. the amount of stress imposed on the stud is limited by the strength of the stud. but the amount of strain (stretch) can be increased by increasing the length of stud which is under this stress. a greater stretch provided better certainty of maintaining the stud in tension under changing conditions. for studs holding down rotating machinery (pumps, compressors and turbines) we would normally require a free length of stud of at least 5 stud diameters to ensure a consistent clamping force holding the machine down to the foundation. in applications with the possibility of very high cyclical loads such as a reciprocating compressor, we would want even longer free lengths on the studs.
johnny pellin
thanks johnny, this explanation is very useful to me. thanks!!
abhijit
thanks johhny, how to decide sleeve pipe diameter. can we use, bolt diameter + 1/2".
to hold down fd & id fans (centrifugal), we are using bolts diameter ranging from 7/8" to 1.5" dia bolts with varing embedment lengths (at least 12"). also can we call sleeve length is 1/2 or 2/3 of embebment length of anchor bolt. for example, for 7/8" dia. ab with 12" embedment, can we call a sleeve of 1.375" dia with 4 to 6" length. your help is appreciated.
thanks,
in our machinery installations, the sleeve is used to keep the stud free from the concrete block and the grout. once the base is installed and grouted in, the sleeve does not see any loads. so, for our installations, we really don't care how much clearance there is between the sleeve and the stud, as long as the stud is free to stretch. i would base the length of the sleeve on the diameter of the stud rather than the amount embedded. as i noted before, for general purpose machinery (such as fd / id fans) would want a sleeve length of 5 stud diameters. so, for a 7/8" stud, i would want a sleeve at least 4-3/8" long. i am not an expert on the proper amount of embedment as this depends on the style of stud, the grade of concrete and whether the stud is connected to the rebar in the foundation block. i will leave questions of embedment to those with expertise in that area.
if you are referring to a sleeve that is above the base plate to provide the free length of stud above the surface of the block, i will also have to defer to other experts. this would place the sleeve in compression making the size of the sleeve important.
johnny pellin
johnny's advice is good, but just to add another thought, over sized sleeves are sometimes used for horizontal adjustment. why don't you ask the fan manufacturer what he wants and why?

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