huangyhg

retrofit of 50ft tall sign
we have a client who is changing an existing sign. problem is with the new wind loads the cantilevered (single pole) 24" pipe no longer works. is there a way to strengthen it? thinking about looking into solid grouting the core, just dont know if thats standard practice, do's vs don'ts.. thanks

" problem is with the new wind loads the cantilevered (single pole) 24" pipe no longer works. is there a way to strengthen it?"
no longer works how? is the pole too weak? is it buried too shallow? is it encased? can it be replaced? can you reduce the sign area? can you weld stiffeners to the pole ? can you provide sketch with dimensions, materials, and design wind speeds ? can you add to the number if poles?
shrink the area of the sign. lower the velocity of the wind. install guys.
for a code change like this where the sign was adequate, i wouldn't be afraid to use the mill certs of the pipe or do some test coupons.
solid grout and center post-tension the pole, embedding the pt reinforcing into the existing foundation with epoxy grout...
mike mccann
mmc engineering
install a raker if you have room and change the support conditions and cantilever length.
back to the basics. when something doesn't work, review the load, review the material strength, review the support conditions.
you did not indicate whether you were increasing the area of the sign. if you are not increasing the area of the sign, does it really need to be upgraded to the newer code? a call to the building inspector may answer this.
discuss problem with the owner. the expense of strengthening the sign might convince him to reduce the size of the sign to bring it into compliance.
yes, here in vegas anytime you make a change to a structure (the area of the new sign is actually smaller than the old one) they want it updated to the latest code (it was intially designed under the ubc). i know, its annoying! it fails in bending. i didnt even get around to checking the caisson footing although i suspect that will be an issue as well. i have another question, would a 50' sign qualify as building category i or ii, .87 vs 1 for my i, anything helps...
i already got all the info, the actual thickness of the pipe, etc...
how about longitudinally splitting a new hss round section and installing it around the original column with groove welded seams. a plate at top and bottom can be used to connect the new sign at top as well as anchor into top of concrete footing at bottom. might need gussets at base.
weld a wide flange to the front and back of the pole.
connection is the hard bit.
try sleeving the base to a height that is required!

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