Are Structural Calculations required? 8

[wil7]

Hi All,
We have a construction project under review by the township engineer(civil). The township engineer is reviewing a large retaining wall, and demanding calculations for said wall. Our structural engineer is not supplying the calculations. Is this a grey area? Thank you,

 

[r13]

But for city building inspectors it doesn't make sense.

In some cities, given the importance of the project, the plans are reviewed by state licensed structural engineers. That's why we respect their comments and requests.

 

[BridgeSmith]

Now for a state DOT asking for bridge calculations, where the client is an engineering entity, then perhaps the calculation submittal makes sense. But for city building inspectors it doesn't make sense.

A bridge design for a state DOT would typically be a different beast altogether, in that, the state is the owner of the bridge and is also charged with ensuring the safety of the public, both on and around the bridge.

If there's a public safety concern because of the location of the retaining wall, greater scrutiny of the design may be warranted and allowed by law. As we saw with the Minneapolis I-35W bridge collapse, the state not having a copy of the design calculations can be a major obstacle to finding the cause of a failure, if it occurs many years later.

It's also possible that the AHJ wants to have the calcs on file in case of nearby construction in the future. Without the design calcs, how would anyone know whether it's safe to excavate in front of the wall, for instance? The AHJ may just have a blanket policy to require calcs for structures of a certain size, without attempting to make distinctions about the type or placement, to cover those types of eventualities.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[JAE]

All good comments -
Calculations, however, are personal and unique.
No two engineers calculate, or document, in the same way.
As such, calculations can be highly subject to interpretation, and mis-interpretation by others.

I've submitted calculations to a city in a big state out west - where they used a licensed structural engineer to review plans (and calcs.)
I spent more time on the phone with this reviewing engineer trying to explain my analyses and calculations that were apparently waaay over his head.

He ended up criticizing the way we displayed our designs on the plans, not the design itself - stupid comments about how to note and schedule concrete reinforcement (our way was standard ACI practice while he liked "his way" better). He didn't even like our north arrow. Just stupid.

 

[r13]

In certain countries, the "North Arrow" is pointing down, and the flow always from left to the right to the left, just to be politically correct

 

[IDS]

The options being discussed seem to be either acceptance of a "sealed" design without further review, or a detailed step by step review of the designer's calculations.

I don't think that makes sense. All designs should have some level of review by someone other than the person who did the original design, and where a detailed review is required that should consist of independent analysis and verification of the end product shown on the drawings. That doesn't require examination of the original calculations, and in my opinion working through a detailed set of calcs is just as likely to conceal a fundamental mistake as reveal it.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[CaliEng]

In my county a retaining wall over 3' in height must have structural calculation

 

[Ron]

Most municipalities do not have staff qualified to review calculations, so submittal is irrelevant. As JAE noted, it is one of OUR "means and methods". They don't ask contractors to submit their means and methods for construction.

 

[r13]

I think there is some confusion here about "provide" vs "submit" design calculation. The former is under request from the agency engineer regarding a specific concern on the design that require clarification, the latter is a procedure requirement. One MUST respond to the request of the former, and shall satisfy the procedure requirement if it is called for, so the permit process personnel can check the box on the check list.

 

[r13]

They don't ask contractors to submit their means and methods for construction.

I think the contractors are required to submit document supporting their plan (means and methods), for erecting structures that affect public safety, and/or using unorthodox method, to obtain construction/erection permit, if required.

 

[BridgeSmith]

..."provide"...design calculation...is under request from the agency engineer regarding a specific concern on the design that require clarification...

...or simply to have on file for future reference in case of subsequent nearby construction or a failure.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[JLNJ]

The IBC does not list calculations specifically, but gives the permitting authority broad reach with a Construction Documents as required for permit notation.

In the Commentary, it does specifically say that Calculations would be an example of an item included in Construction Documents.

 

[r13]

Note, IBC rules the way how you design only, it does not rule the AHJ. The AHJ shall abide by the laws, the regulations, and/or local ordinances, which may, or may not accept IBC.

 

[Guest090822]

We had a town engineer requiring calculations. Turns out, he was copying designs for a side business that ended up being a total conflict of interest. He got fired and dragged through the papers for awhile. I’d demand to know the local law and force the town to cite it if they need the calculations.

 

[r13]

Rick,

Good example. Actually, in this case, the calculation helped to expose this guy's unlawful act. If he had copied the design details without the calculation, or nobody demanded to see/check it, he might still sit behind his desk and copying. Although his lack of understanding on copied materials would expose him too, some day, some way!

 

[jakeh76]

Virginia has this section that gives the AHJ a lot of latitude in what they may request.

‘109.3 Engineering details

When determined necessary by the building official, construction documents shall include adequate detail of the structural, mechanical, plumbing or electrical components. Adequate detail may include computations, stress diagrams or other essential technical data and when proposed buildings are more than two stories in height, adequate detail may specifically be required to include where floor penetrations will be made for pipes, wires, conduits, and other components of the electrical, mechanical and plumbing systems and how such floor penetrations will be protected to maintain the required structural integrity or fire-resistance rating, or both. All engineered documents, including relevant computations, shall be sealed by the RDP responsible for the design.”

 

[STrctPono]

He ended up criticizing the way we displayed our designs on the plans, not the design itself - stupid comments about how to note and schedule concrete reinforcement (our way was standard ACI practice while he liked "his way" better). He didn't even like our north arrow. Just stupid.

I think this happens quite a bit in QA/QC scenarios where one Structural Engineer is hired by an entity to provide either quality control or quality assurance. Imagine going through a set of plans and not having any comments? Sometimes, in order to show that you "earned your fee" some comments need to be made, even if it's as idiotic as not liking a North Arrow!

In my municipality. Submitting calculations with any permit set of drawings is just implicitly understood to be required. However, I sometimes wonder if the plan checkers for the residential side of the building department ever even graduated from high school. I've unfortunately witnessed plans and calcs submitted for million dollar homes with retaining wall footings drawn backwards, houses supported by sky hooks, 20 ft long spanning 2x8 floors, etc, and accompanied by a supporting calculation package that merely showed a few primitive glulam beam calcs. No comments from building department.

 

[Settingsun]

Perhaps the engineer has this book and has never needed to calculate a retaining wall:

https://books.google.com.au/books/a...aining_walls.html?id=--1RAAAAMAAJ&redir_esc=y

600 odd pages of tabulated walls. Or any of several other similar tables produced by people selling concrete, reinforcement or masonry.