Steel Tower
Steel Tower
(OP)
Attached is a sketch of a free standing marque our client wishes to to erect at the entrance to his business premises. I have been working on a solution assuming portal frame behavior. The extreme aspect ratio has me a bit anxious and wondering if the usual assumptions which are made for a portal frame are appropriate without adjustment. I wanted to use cast in place piles but they are so close together they will interact. A concrete frost wall on a footing may be more logical. Any suggestions?






RE: Steel Tower
Your overturning moment is high, so a footing will have to be quite large to react that moment x 1.5 or 2 depending on your code provisions. For that reason, a drilled pier or two large augered concrete piles with a cap to support the structure makes more sense. Yes, with two augered piles you'll get interaction, but as long as you account for that, it's ok.
Since this structure is stucco covered, advise your client that waterproofing the stucco facade is extremely important. The stucco system should be designed as a drain plane or rainscreen system, not a face barrier system.
RE: Steel Tower
Also, seems like a spread footing would work if you have enough real estate
RE: Steel Tower
steel columns and the hold-downs, and one single pad footing with enough soil overburden to counteract the uplift.
Alternatively, you may have four individiual piers for four columns connected at the top by tie beams and one common pad footing.
Bringing in another trade for deep foundations does not seem a good idea unless the soil is very poor.
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Also, helical foundations can be installed by smaller tractors about the size of a bobcat. But I think you would need four, one at each corner.
RE: Steel Tower
I like that or the idea of masonry above. Is a spread footing an option? If so, masonry would give you extra dead weight to resist OT. Not sure if seismic is a governing load though.
RE: Steel Tower