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Braced walls with no footing

R

retire09

Silver Member
Joined
Feb 19, 2010
Messages
365
Location
Alaska
I have received documents from an engineer showing braced walls over a 4" slab on grade anchored with 5/8 Redheads.

This is for a commercial building in a 110mph wind zone and seismic category D.

I know the residential code would require a minimum 12" footing from top of slab for these walls per R403.1.4.2.

I am not an engineer but this does not look right to me.

The engineer insists it is OK and the building is already dried in.

Should I challenge this?
 
No calculations were provided.

The design was done by a nonregistrant and only the cover letter was sealed by the engineer, the 15 pages attached are not.

I have refused the submittal and required all pages to be sealed. The engineers says he has never had to do that before.
 
He sealed the plan as previously submitted.

The building is single story wood frame and the back wall is 209' long with 2 intersecting interior shear walls each 24' long supported on a 4" slab. It is an apartment building and has 11 other intersecting walls but only 2 identified as braced walls.

Should I be concerned?
 
I would think that they would be at least a thickened/monolithic slab. Is it only 4" at the intersecting shear walls or on the exterior walls as well? Redheads can be used with 4" embedment if they use the right one so it may be OK. The engineer did not hesitate to stamp it so ask him to provide the calcs like others have said.
 
In some states the licensing laws may only require the first page of a report be signed.

The fact that the work was done by a non-registrant may imply the engineer was not in control of the work and thus could be in conflict with state licensing laws. Check with a local engineer or the state licensing board.

I do not believe that this will work in SDC D.
 
As confusing as 602.10 is, there is no requirement for all braced walls to be bearing walls; no footing required by Code.
 
1808.6.2 Slab-on-ground foundations.

Moments, shears and deflections for use in designing slab-on-ground, mat or raft foundations on expansive soils shall be determined in accordance with WRI/CRSI Design of Slab-on-Ground Foundations or PTI Standard Requirements for Analysis of Shallow Concrete Foundations on Expansive Soils. Using the moments, shears and deflections determined above, nonprestressed slabs-on-ground, mat or raft foundations on expansive soils shall be designed in accordance with WRI/CRSI Design of Slab-on-Ground Foundations and post-tensioned slab-on-ground, mat or raft foundations on expansive soils shall be designed in accordance with PTI Standard Requirements for Design of Shallow Post-Tensioned Concrete Foundations on Expansive Soils . It shall be permitted to analyze and design such slabs by other methods that account for soil-structure interaction, the deformed shape of the soil support, the plate or stiffened plate action of the slab as well as both center lift and edge lift conditions. Such alternative methods shall be rational and the basis for all aspects and parameters of the method shall be available for peer review

1808.8.6 Seismic requirements.

See Section 1908 for additional requirements for foundations of structures assigned to Seismic Design Category C, D, E or F.

For structures assigned to Seismic Design Category D, E or F, provisions of ACI 318, Sections 21.12.1 through 21.12.4, shall apply where not in conflict with the provisions of Sections 1808 through 1810.

SHALLOW FOUNDATION. A shallow foundation is an individual or strip footing, a mat foundation, a slab-on-grade foundation or a similar foundation element.

SECTION 1809

SHALLOW FOUNDATIONS

1809.1 General.

Shallow foundations shall be designed and constructed in accordance with Sections 1809.2 through 1809.13.

1809.2 Supporting soils.

Shallow foundations shall be built on undisturbed soil, compacted fill material or controlled low-strength material (CLSM). Compacted fill material shall be placed in accordance with Section 1804.5. CLSM shall be placed in accordance with Section 1804.6.

1809.4 Depth and width of footings.

The minimum depth of footings below the undisturbed ground surface shall be 12 inches (305 mm). Where applicable, the requirements of Section 1809.5 shall also be satisfied. The minimum width of footings shall be 12 inches (305 mm).

See IBC Section 1808 for the foundation requirements
 
It does not apply to commercial but that along with the fact the engineer called for a 10" anchor bolt in a 4" slab, did not seal the plan and then insisted he did not need to seal the plan contrary to state statutes are all clues that he may not be very good at what he does.
 
I am not an engineer but I have never seen braced walls supported on a 4" slab before and with the residential and building code sections we have discussed, I thought this might be worth investigating.

This engineer has submitted plans not only unsealed but with changes made with whiteout to me in the past.

He has been in trouble with the State in the past for working out side of his area of expertise and I have no confidence in his abilities as a "design professional".

Now that he has at least sealed and signed the plan I think I will let it go if no one feels it is a potential problem.
 
The footing not being a minimum of 12" would alarm me which would catch most of the required anchor bolt lenght. Rebar or mesh in slab?

In my state the plans, calcs, reports, specs, estimates prepared by the licensed professional or under his supervision must be stamped or sealed making the RDP responsible for the contents of all documents. Changes to the plans need to be stamped as well. They do not have to seal preliminary or incomplete plans or documents.

IBC 106.1 allows the BO the right to require more information or documentation.

pc1
 
Consult with a local engineer and consider not issuing the building permit.

My sense is that you will find several non compliances. Unless there is a proscriptive provision in the code allowing him to do what he is proposing to do you can require technical justification and hold the permit until that happens..

I suggest that there should be an expectation that if a jurisdiction does not have a licensed engineer on staff they should have a relationship with an outside consultant who can provide the necessary technical backup. We should recognize that there is a real question about the ability of a building department to fulfill its duties and protect the public if it cannot meet that expectation.
 
With a 200' long building in SDC D with only two interior braced walls that are anchored with 5/8" expansion anchors into a 4" slab on grade, there is a potential problem.
 
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