Jib Crane Anchor Bolts 1

[tactical14]

I'm looking to purchase a Jib crane for my work. I've been in talks with a company who gave me the following information. The over turning moment is 60,833 in-Lb and the bolt pullout force is 2150 lbs. Using a recommended safety factor of 4, I should design around a bolt pullout force of ~8600 lbf.

I'm not sure the compressive strength of my concrete, but can I just assume 2500 psi? I would like to stay away from reinforcing the concrete if possible. I do know my concrete is 6" thick.

I've been looking at the 3/4" Red head wedge anchor and the pullout strength at an embedded depth of 4.75" is 10561 lbs,

My question is there anything else I should consider when looking for anchors?

 

[TheLinker]

Yes, ACI 318 Appendix D.

Anchor selection is not as simple as applying a FS of 4 and using vendor table values. Appendix D addresses all that is required for anchor designs (anchor spacing, edge distances, etc...).

If you are not familiar with ACI 318 it may make sense to get someone who is.

 

[hokie66]

You are worrying about the wrong thing. Not saying the anchors are unimportant, but a 6" slab is not adequate for support of a jib crane.

 

[dik]

You may want to look into using Hilti HSL anchors. I've done a few jib bases snd have secured a steel plate with threaded studs because of reinforcing locations.

I've included an earlier procedure that I've used

PROCEDURE FOR POST INSTALLING JIB CRANE BASE PLATES

LOCATE CENTRE POSITION FOR PROPOSED JIB CRANE

LOCATE FLOOR SLAB REINFORCING IN BOTH DIRECTIONS USING A REBAR LOCATOR

PROVIDE CHALKLINES TO SHOW LOCATION OF EXISTING REINFORCING STEEL ON THE SURFACE OF THE FLOOR SLAB

USING THE JIB CRANE CENTRE, LOCATE CENTRES FOR HILTI HIT-TZ ANCHORS

POSITION HOLES TO FOR THE NEW ANCHORS TO CLEAR EXISTING REINFORCING. DO NOT CUT REINFORCING STEEL. IF REINFORCING IS ENCOUNTERED, TERMINATE HOLE AND RELOCATE ANCHORAGE CLEAR OF ANY REINFORCING STEEL

ADVISE FIELD ENGINEER IF REQUIRED ANCHORAGE LOCATIONS CANNOT BE FIELD ADJUSTED TO AVOID REINFORCING STEEL AND AWAIT FURTHER INSTRUCTIONS

PROVIDE HILTI HIT-TZ ANCHORS TO MATCH JIB CRANE BASE PLATE HOLE LOCATIONS. ANCHORS TO MATCH DIA OF ANCHORAGE BOLTS

USING A CARBIDE BIT, DRILL HOLES IN EXISTING CONCRETE FLOOR AT ANCHOR CENTRE LOCATIONS AS STIPULATED BY ANCHOR SUPPLIER

THOUROUGHLY CLEAN OUT DRILLED HOLES AND BLOW OUT ALL LOOSE ‘DUST’

TRANSFER ANCHOR LOCATIONS TO PLYWOOD TEMPLATE FOR SETTING ANCHORS

INSTALL 8 HILTI HIT-TZ ANCHORS IN HOLES USING HILTI HY-150 HIT ADHESIVE. ANCHOR EMBEDMENT SHALL BE TO MANUFACTURER'S PRINTED INSTRUCTIONS

ADHESIVE SHALL CURE IN ACCORDANCE WITH MANUFACTURER’S RECOMMENDATIONS

REMOVE PLYWOOD TEMPLATE

PROOF LOAD HILTI-TZ ANCHORS TO THE MANUFACTURER’S SERVICE LOAD CAPACITY

PROVIDE A 1/8” THIN SET STERNSON M-BED GROUT LAYER ON THE EXISTING SLABS OVER THE AREA COVERED BY THE STEEL SUPPLEMENTAL JIB BASE PLATE

REMOVE EXCESS GROUT MATERIAL AND LET GROUT HARDEN

INSTALL JIB CRANE OVER HILTI ANCHORS. INSTALL NUTS AND TIGHTEN TO SECURE JIB CRANE

JIB CRANE BEAM SUPPLIED SHALL BE PERMANENTLY MODIFIED TO PROVIDE MAX CRANE SPAN STIPULATED

PRIOR TO BEING ‘PUT INTO SERVICE’ JIB CRANES SHALL BE PROOF LOADED TO TWICE THE STIPULATED SERVICE DESIGN LOAD. TESTING SHALL BE IN THE PRESENCE OF A THE [CONSULTANT | ENGINEER]

THE MAXIMUM STIPULATED SERVICE LOAD CAPACITY SHALL BE PAINTED PERMANENTLY AND PROMINENTLY IN 6” HIGH MIN LETTERING ON THE JIB CRANE BEAM IN A CONTRASTING COLOUR

Use as a general drift... modify to suit...
Dik

 

[TDIengineer]

You are worrying about the wrong thing. Not saying the anchors are unimportant, but a 6" slab is not adequate for support of a jib crane.

Agreed. What transfers your moment and vertical load to the ground?
Also, with just a 6" base material thickness you're not going to get much embedment depth allowed.

Download Profis, it's free and will check the anchors for you. Use cracked concrete to be safe, and 2,500 psi is a good assumption.

You'll be wanting to remove the slab and place a thicker larger slab with dowels into the (e). I am thinking more like 12" thick, min.

Click on Link below for Profis.
PS> Maybe hokie can size that footing for your assuming 1000 or 1500 psf soil bearing capacity.

Link

 

[racookpe1978]

OK.

So assume he doesn't want to cut out the 6 inch concrete floor and replace it with 12 inch deep slab over a region wide enough to anchor the jib crane.

Could he "back-calculate" how wide a frame he needs to reduce the anchor bolt loads enough so a 6 inch slab would work? That is, he figures out how many anchor bolts (4x, 8x, 12x ?) over what area of concrete would allow him to stay below the pull-out stress of a 6 inch nominal slab of 2500 psi concrete? Then, obviously, he'd have to connect that frame to the floor, then the jib crane to the frame.

 

[dvd]

I would recommend to follow the crane manufacturers foundation recommendations. This link provides some guidance on foundations for Gorbel cranes. It just seems like a good idea to have followed the crane manufacturers directions if you find yourself in a courtroom.

https://www.gorbel.com/resources/products/jibcranes/ibeam/documents/FS-Jib.PDF