Beam schedule w/ service loads

[JStructsteel]

Got a beam schedule from some drawings, call out span, width, etc and then the Mmax and Vmax at service level. What is the point of that, when I need to know DL and LL?

 

[WesternJeb]

What is your role?

 

[JStructsteel]

Designing the beams.

 

[jayrod12]

Maybe they were anticipating you using ASD design methods and therefore don't see the need to provide any other information.

 

[phamENG]

Wait a minute. Did somebody just delegate the design of the beams? Is that a thing now?

 

[jayrod12]

Wait a minute. Did somebody just delegate the design of the beams? Is that a thing now?

Lately I've been getting projects where the EOR has designed the entire building right down to the pile loads, but delegated the actual design of the piles. I could understand if the EOR wasn't local or the owner was refusing to get a geotechnical report or something, but in all cases the EOR has been local (so he knows the typical foundations used), there has already been a sealed geotechnical report with driven pile capacities. I can't imagine they saved a significant amount of design or detailing work by delegating the pile designs, but I guess I can't complain since it allows me to charge way more for a pile design than I would normally of included in the fee if I was the EOR for the same level of work.

 

[JStructsteel]

@ Jayrod12, I didnt think that was a thing with concrete. Isnt 318 code a LRFD design theory?

@ PhamENG. Everything is delegated anymore, lol. No, these they want precast beams, so precast engineer (me) to design.

 

[WesternJeb]

Ah, that is the missing piece of the puzzle as I believe we were assuming steel design.

It seems to me like you should send through an RFI then asking for the LRFD equivalents, and that this EOR clearly doesn't know what they are doing. The other option is to throw a 1.4 factor on each of the numbers and go with it, but that extends a certain amount of liability on your end.

 

[phamENG]

Yeah. Connections are bad enough...but the rest of it? I once ran through with a client all of the things my boss told me to delegate on a design. He looked me in the face and asked "So, what am I paying you for, then?"

If we're not careful, we're going to delegate our way out of a job...

JStructsteel - that's how I end up seeing most things. I did delegated designs for a canopy manufacturer for a while. I was constantly sending RFIs asking for breakdowns of loads. Rarely ever got them.

 

[phamENG]

Oh. Wow. Yeah...service level doesn't lead one to think concrete...

 

[JStructsteel]

Sorry, yea, that's what makes no sense, service loads for concrete.

Right now I am doing prelim design for pricing. I am checking 1.6 on the service loads, if that works, then I know that I can get into the loading (I have drawings) and then design appropriately.

Yes it will cost the customer more in the end, but they need pricing by Friday, so be it. Perhaps a RFI would be appropriate too. But in the end, I need to check the loads are correct.

 

[jayrod12]

Yeah sorry, I has just assumed steel, maybe it's your username that swayed me the most.

I don't practice down south, so I didn't even know that ACI was fully LRFD. I wonder how long AISC will hold onto the ASD side of the book.

 

[KootK]

What is the point of that, when I need to know DL and LL?

Meh. It's hard to perfectly delegate something.

I do some precast and have developed a trick for beam design that might interest you. No matter what the load, I design the beam as if the total load were two point loads at the third span points. If there are dense stirrups at the end, I reduce them in the middle 1/3. Then I check the real moment and shear demand diagrams against capacity diagrams developed this way. If more capacity is needed, I bump the faux point loads up to deal with that.

This has the following benefits:

1) This is pretty easy to automate.

2) I wind up with beams that can adapt to a lot of variations in loading. A bit like the KCS steel joists.

3) I wind with beam designs that repeat a lot.

4) The extra cost of beams designed this way is nominal, particularly given the benefits that accrue from symmetric reinforcing.

For your situation, I'd factor the moment and shear up as you suggest, convert that into a pair of concentrated loads, show the capacities to the reviewer, and move on to the next design.