Metal Building Foundation

[TexasPE]

I am trying to get erected a 30 x 40 ft Metal Building in an area 75 miles from the Gulf Coast for my personal use for a garage with a FEMA 320 safe room. I have specified a 120 MPH metal building with 2-3x3' fixed louvers over 6 feet up, 2-10 foot ridge vents, 2-120 mph wind certified overhead doors and 1-130 mph walkdoor. The resultant column loads are pretty ordinary except for the main center column on a side wall. My contractor has quoted a 14" wide by 20-24" deep perimeter beam with 4 #5 with #3 stirrups 24" oc under a 4 1/2" slab with #3 15" o.c.e.w. based on a similar design for the same size building in the area on 45 PI soil expansive (Lake Charles type) clay soil. We were going with that until we got the certified drawings back and a structural engineer could look at the foundation design.

However, I just got back the sealed design and the combined loads on the side wall center column ranged from 24K to-37k vertical and required the addition of a wind column brace by the metal building engineer which has about a 30k ft-lb moment. The opposing main center column minimum vertical reactions under this column are only in the -11k range.

I was assuming we could add a 10" wide x 2 foot long pilaster to the perimeter beam to take the main column anchor bolts. We lengthened it to 5 feet centered on the main column due to the wind column brace.

At the suggestion of a structural engineer, who was to busy to take the work but was willing to take a quick look at the design, the 8' x 8' x 8' concrete safe room 30" wide by 12" deep grade beam was being integrated with the perimeter beam under the other side wall columns anchor bolts. Of course he is now on vacation.

My soil from 6" down to about 6-8 ft is silty clay PI ranging from 20-40 but the water table can vary seasonably from -30" to -6" in our area.

My designer reports the overall design is just not working.

I am not a structural or civil engineer by education. I have had some experience as a construction engineer doing compressor stations for pipeline companies and have picked up enough to know I am in over my head. I kind of suspect that the building engineer has pulled the old grenade over the fence and sifted the design problems of the high wind load to the foundation contractor by just fixing it at the one column.

Every structural engineer I have talked to about looking at this in my area is backlogged. I have asked the contractor and building manufacturer to hold up but not sure how long they will agree. They both think since this is for a farm and doesn't require any permitting or inspection that we should just go with the contractors design.

Has any one out there run across this problem and have any other design alternatives to suggest? Should I be getting a second engineering opinion on the metal building design?

 

[UcfSE]

You should have a structural engineer functioning as your engineer-of-record. That person would then have the authority, as worked out in your contract and state law, standard procedure, to direct the metal building engineer to do as is required. They are in the business of selling buildings, not necessarily cooperating with the rest of the team to provide the best service for the owner. An example of this is fixing the footing connections though you don't want that done. It saves them headache and steel. What it does to others doesn't matter.

I know you can't seem to find an engineer in your area. You may have to look outside your area. If you are not required to have inspections and sealed drawings, then you may have a way out but is an assumed risk. Your state board's website may have a directory of registered engineers you can check out.

 

[TexasPE]

UsfSE is right. Like an attorney, if I as an engineer try to represent myself I have a fool for a client. I could go to the roster on the TBPE website and I have used it to try to locate a good engineer, but most structural engineers work for the larger firms which don't want to take this job for the cost that it should support and names of engineers working for themselves without references is not very valuable. Cost is a consideration. This is at most a $40K job. I can't afford to spend $40K for the engineering.

Plus on the contracting side I find I have very little negotiating room. Contractors are generally busy and don't want to negotiate. I have had several just refuse to return phone calls after they hear what is being proposed. Metal building vendors don't want to allow you to read their contracts before you order their building and then it's a contract of adherence. Take it or leave it. Client input with their engineers. Forget it.

 

[UcfSE]

That's tough, I'm sorry not to be more help. All I can suggest is keep trying to locate someone. Texas-registered engineers may be out-of-state also. That may be an option if you can find no one local. Also, there are engineers at big companies who will also do side jobs. That may be another option.

The reasons you cite are part of why I don't have much use for pre-engineered metal buildings.

 

[TexasPE]

Good News. Found a Structural Engineering Firm in CA that specializes in Metasl Building Foundations. Has licensed engineer for Texas. They are working up a new design. Should be done by Tuesday.

 

[UcfSE]

Good for you! Thanks for the update.