When is a detail required? 3

[Bowsers]

Hello,

Sorry for such an entry level questions. I did a forum such but nothing came up of use.

I am curious when a detail is required. What, in general, should be signaling to me that a detail is required?

Secondarily, if a detail is required, when is it ok to specify a prescriptive detail vs. drawings one up?

Thanks

 

[271828]

If a reasonable engineer can't figure out with certainty what's going on fairly easily, then add a detail. Err on the side of more details.

The other guy doesn't know how the detail came about. If your firm has a standard or typical detail that's just like the current condition, then use it because that'll be faster.

 

[dik]

I came from a time period where if a condition was different, another detail was drawn... it's changed... you need as many details in order to provide an intended outcome.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Harbringer]

If a reasonable engineer can't figure out with certainty what's going on fairly easily, then add a detail.

I disagree. Engineers don't build buildings contractors do.

You should add at a unique detail at locations that the structural elements are not already clearly covered by your typical details.

What, in general, should be signaling to me that a detail is required?

Generally details are covering connections of some sort and if you require unique detailing to ensure a continuous load path you need a detail.

 

[JedClampett]

The more you detail, the more control you have. If you give a contractor a choice, he's likely to pick the least expensive, least trouble for him.
You certainly want to detail anything that you've needed to make your calculations work, i.e. number of bolts, weld sizes, connecting plate thicknesses.
Otherwise, if there's a industry standard, you can use that. For instance, "use an AISC Table 10-1 connection with 5/16 inch angles and 3/4 inch SC Class A bolts" is safe. Or ACI standard hooks.
As 271828 said, this is why bigger firms have typical details. Much easier than stating from scratch and they can be customized or your work. Our company has typical steel connections, but they're light and not appropriate for a boiler building. But we don't do much heavy steel design, so they're fine for us.

 

[271828]

I disagree. Engineers don't build buildings contractors do.

Not clear what you're disagreeing with.

If the condition is unclear from the plan linework and text, then add a detail, right?

Otherwise, what's the contractor supposed to do? Guess? Send an RFI?

 

[dik]

I often see drawings where the engineer assumes the contractor is technically equal and requires the contractor to do stuff that an engineer would normally do. I recently started a thread. I posted it because I thought it was funny... I was going to add a note for the EOR to confirm a couple of cinder blocks on firm bearing under the beam would suffice...

thread507-479595

indicating an extreme of this...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

...a good engineer has to know how to build them. and, occasionally better than the contractor. You don't want to overstep the boundary where a contractor is 'an expert in construction' for liability reasons.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Harbringer]

Not clear what you're disagreeing with

If a reasonable engineer can't figure out with certainty what's going on fairly easily, then add a detail

The "target audience" of your drawings are contractors not engineers. What another engineer can figure out is irrelevant.

I'm saying the standard you should hold your drawing to is: If a moderately competent contractor can't figure out with certainty what's going on fairly easily, then add a detail

 

[271828]

The "target audience" of your drawings are contractors not engineers. What another engineer can figure out is irrelevant.

I'm saying the standard you should hold your drawing to is: If a moderately competent contractor can't figure out with certainty what's going on fairly easily, then add a detail

Yes, I'm fine with that. I probably should've said "contractor."

I do delegated design for fabricators, so I often find myself trying to figure out what's going on in the structural drawings.

 

[BAretired]

The competency of a contractor is not known when drawings are prepared.

A detail is required when the plans, sections and typical details do not show clearly what is required.

BA

 

[kissymoose]

In other words, it's subjective. There's no governing body or code requirement that tells you what to detail and what not to.
Say your drawings have no details and only provided member sizes. The contactor can provide all the right member sizes and then tack weld everything together. The resulting deficiencies are on you (probably not completely). Present all the information you need to communicate a comprehensive load path, which can be in the form of specifications, drawings, and references to governing codes/construction standards. If something can be constructed incorrectly but meet the requirements of the construction documents you provided, you needed more information/detailing.

 

[dik]

and the corollary to that is contractors don't design buildings, engineers do...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Bowsers]

Wow, thanks everyone for the input. I thought it might there might be a prescriptive answer, such as "an engineering detail is required when a connection transmits over 50#/200#/500# of load" otherwise up to the engineers judgement. What I'm gathering is that it is always up to the engineers judgement.

 

[Altu1976]

Yes it is, but bear in mind that the design is yours and if you do not convey all you ideas clearly then, you are responsible; you can not assumed the contractor will know what you were thinking.
As others commented, standard details help a lot if you have repetitive or similar jobs. I detail even my end supports for simply supported steel beams, pad stone and blockwork distribution just to be absolutely clear.
That details reduce the amount of enquiries about your design by the contractor or the building inspectors.
The advise is start preparing your own archive of details so you can use them without causing delay.

 

[Brad805]

Some of this will also depend on the industry you work in. Some groups have tools that make it very easy to generate RFI's and can drive you mad with requests.