Engineer wanted splice on middle post 9

[hgcdesign]

hello guys , this may be a dumb question but I'm going to ask anyway. The engineer of record on a house I'm building wanted a steel beam spliced on middle post with a concrete pad of 24x24" . I built it with a 34x34 concrete pad and just left the post solid because it came that way and seames to make more sense not to cut it , I still supported it on the middle post . Now he is telling me I have to redo it because the pad needed to be 36x36 for a solid beam . This makes zero sense to me but I guess I could be missing something. Beam is 50' Thanks

 

[dik]

Seems silly... but why would anyone use a 34x34 footing in lieu of a 36x36?

Dik

 

[hgcdesign]

I apologize if we got into the weeds . I will post the drawings shortly . The pad was originally requested at 24"*24" . My foundation guy always makes everything a little bigger which for the most part I've always been ok with. The main structural beam of the home was designed with 3 post and a splice in the middle . When they delivered the beam it was 1 peice 50' long so I told them to go ahead and put it in solid . The question was more so for my personal understanding of the beam needing a bigger concrete pad on the center post since it was solid then it needed for a splice which I do understand now. However the engineer wants us to either splice it or make the concrete pad bigger by 2"*2" which seemed silly to me. The entire 50' beam has 3 post , 1 every 12.5' all requested at 24"x 24" but were poured at 34"x34" .The EOR requested the center be 36*36 if we wanted to used a solid beam. I'm more than happy to splice it , that is the way it was drawn I just like to save my clients a little money where possible and my welder isn't cheap.

 

[TrussBridgeboy]

There are so many assumptions in loading, soil capacity, material strengths, factors of safety, and the like that a slight difference in actual vs. theoretical should be fine. Sounds like the engineer in this case (and I’ve run across my share of Dr. dot the I and cross the T’s) might be “good” but lacks a grasp of the bigger picture. Have him assume say 1/8” settlement of your “overloaded” footing and recalculate! The footing will see much less load.
[tt][/tt]

 

[r13]

1) Who justified 34"x34" pad instead of designed 24"x24" pad, wasn't that a waste, if un-necessary?
2) Enlarge the footing 2" each side is much cheaper solution than splicing the steel beam, and provide/install necessary connection parts.
3) I don't know how you are going to be reimbursed, but it seems to me, the save is on you to offset the cost of footing enlargement, not to the pocket of the owner, as he pays for the estimated cost on the contract, deduction can be done on major change only.
4) In the whole discussion, no one seems to care how much problems the EOR has to deal with, due to this last minute change. Who is going to reimburse his additional efforts to correct this wrong doing? Not the contractor, I believe, nor the owner.

 

[Tomfh]

So the beam was designed as continuous over the other posts, and they were designed as 24x24 footings? Now I’m really confused...


Edit: ..confused as to why a 34x34 is inadequate if 24x24s were adequate for continuous supports.

 

[hgcdesign]

All post were designed at 24*24 . Spliced in the middle continuous over the others. My foundation guy pays for the concrete overage , he makes things bigger just to be safe. If there are any cost that the engineer I cover them. But that's none of the concern my point was why 34*34 wouldn't be sufficient if 24*24 was sufficient for a spliced beam. That's all, again it was more for my knowledge not to get in a pissing match with the engineer we will of course do whatever is asked , I made the decision to go with the continuous beam I will cover cost , as if any of that matters to the question.

 

[hgcdesign]

 

[radiocontrolhead]

hgcdesign,

I was very confused mainly because you were calling a beam a post in the first post, and now your last post you are referring to foundations as posts?

I am in agreement with retired's comment above that if the job was bid assuming a 50 foot steel beam could be installed in lieu of the specified splice then that ones on the bidder, not the point as we like to discuss theory here as you mention.

We understand that everyone trying to save money and be more efficient, we get that but at this point I'd be more concerned about having to redo work that was already done, which is probably where the money lost will be.

I'm in agreement with the other opinions on here that you should probably go straight to the designer or a head engineer and fight this one because the increase in footing size doesn't seem to make much sense. That's a much larger foundation, for the relatively smaller increase in reaction.

 

[hgcdesign]

Yes sorry I have both my boys and was trying to voice text this and just confused everything. The beam is 50' , 3 post, 3 footings ,specd at 24*24, poured at 34*34

 

[hgcdesign]

I was just trying to figure out if I was out of my mind for thinking that was way over kill regardless if he's trying to do it just to prove a point because we changed the design. Which is understandable because he drew it a certain way and we changed it

 

[nac521]

Yes way overkill. To repeat JLNJ said, it only increases the reaction by 12.5%. However, why not ask the question (RFI, etc) prior to making the change to avoid all this mess? This seems common in residential construction; make the change, then ask if ok after.

 

[hgcdesign]

Well their office was locked down and on quarantine and nobody responded to emails for 3 days before I made the decision to start framing we were behind due to weather the last few months in Colorado as it was and this needed to go in to start the rest of framing and in my mindset it was a no brainier that it would be ok . So I made the call. For the most part we try not to make changes but sometimes things don't work as designed but we get it redrawn before we continue this was a little different circumstance . I received a response 10 days after the fact.

 

[hgcdesign]

I've always had the mindset of why cut something if you don't have to, this is the first time it has cost me , so not doing to bad. But thanks for all the responses and less anyone think other wise we always compensate our engineers for any time not planned in original bid and don't charge the client unless it's at their request.

 

[Tomfh]

In general I think you’re correct to not weaken a member if you don’t need to. Sometimes you need a joint, but it’s fairly rare that continuity isn’t better and stronger.

For us it’s normally the other way around. Contractors cutting up beams because they’re too long...

 

[ldeem]

I'll take a stab, first off it seems more of a pissing match than anything - except that the engineer did (I assume) recalculate to come up with 36x36 instead of 34x34. It sounds like you already poured it so I would wonder if they knew you poured 34x34? I don't know how you would add 2" more concrete to the side and have any hope of pinning such a small amount to the existing. Might be worth going a measuring the actual footer size to see if your contractor poured it larger than 34x34.

The spans aren't equal so it may be a situation where they are trying to even out the bearing pressure in order to avoid differential settlement between footer and wall? Zooming into your drawing I see all three footers look to be a different size. This would seem to confirm my theory that the size is more about maintaining similar bearing pressure than actual size. Changing from two span to one span would also change the load distribution and the footing size.

From an engineers perspective I deal with several contractors. I consider myself fairly agreeable and open to change if it makes the job go better. However it can be very frustrating when changes get made and I don't find out until after the fact. I often deal directly with contactors and take calls 24/7 so I don't see any reason that if someone wants a change they don't call and quickly discuss it.

Not all the time but sometimes designs are a certain way to accomplish something that may not be obvious - in this case the three different sized footers lead be to believe that is what is going on.

I get your comment that your name is on things so you want to go the extra mile to beef up the design. However the engineer is also on the line - if there is a serious problem and someone starters asking why the beam is a certain size, footers a certain size, etc. that liability is back on the engineer. E&O insurance isn't cheap and there are no LLC's to hide behind if there is a design error.

 

[hgcdesign]

Yeah I totally understand and in this day in age everyone is trying to cover their ass. And no we wouldn't add too, we would have to just re pour but if we can't come an agreement I'll just splice it , not worth argument, I just wanted to learn for my benefit because I have never encountered this particular issue.its hard for we to wrap my mind around a spliced beam on footer vs a solid even needing to have a bigger footer let alone that much. The EOR wouldn't explain to me why just said we needed to.

 

[r13]

Let's do some math. Note the dimensions may differ due to difficulty in reading the plan.

Tributary area of the larger support on the left A1 = 12*12.5=150 SF, the middle support, A2 = (6.25+4)*12 = 123 SF
Assume 150 psf load, P1 = 0.15*150 = 22.5 kips, P2 = 0.15*123 = 18.45 kips
It looks like the middle support pad is 2'x2', back check the bearing capacity for axial load only, fa = 18.45/4 = 4.6, say 5 ksf
Thus the required pad for the larger support Af1 = 22.5/5 = 4.5 SF

It seems the 3'x3' pad size is excessive without moment at the base. But...I won't bother with a mere 2" deviation, and I believe the EOR thinks the same, but communication is the key.

 

[dhengr]

Hgcdesign:
Funny thing about this thread, and your actions…, you are the builder (or GC) not the Engineer (EOR) who signed the plans and who was the person the owner hired to design the building to the local bldg. code, for permitting, etc. We can spend days guessing at what really happened, based on a fairly half a$$ed explanation of the facts, and we still won’t turn you into an engineer, so that you undertake and assume the EOR’s responsibility and liabilities. Didn’t anyone ever suggest to you that you ‘FOLLOW THE DAMN PLANS,’ and then you are in the clear if anything goes wrong. If you want to make alterations or changes, you should clear these changes with the engineer, so there is no question later. Build your case, show your savings or improvements to the engineer with a complete and intelligent explanation and pass the saving on to the owner, not into your own pockets, and usually you should be well received.

Either you or the stl. supplier deviated from the plans without pre-approval, and you didn’t check the shop drawings, or didn’t bother to request any shop drawings, so this bull lies with you. There usually is a reason for some concern about the first interior post/ftg. loads for the scenario that you presented, although in this case, for these light loads and small spans adjustments probably could have been made, with a diplomatic approach to the engineer. If 24” sq. ftgs. where o.k. under two 25’ long 2 span continuous beams each 12.5’-12.5’ span lengths, center splice over a column, and 12.5’-12.5’, the worst post load would already have been contemplated and covered. Undoubtedly, the engineer’s thinking for the two 25’ beams was transport and site handling of the full length beam, not to spite you or the stl. guy. What about the change in TJI’s, is the floor elev. now 2” higher or did they loose 2” in clg. height? Does this cause interference with any mechanicals, before they get there with their chain saws, and who fixes and coordinates all this?

It is not uncommon for the engineering office to send out young engineers on what should be fairly simple inspections (construction observations). They are usually not experienced enough to make changes on the fly, so they will tend to follow the plans, and call you on deviations from the plans. There is usually no sense in arguing with them, nor should it be taken as disrespecting them when you go to their boss to try to iron things out. But, don’t assume they were disrespecting you either for asking you to follow the plans, plans and specs. aren’t called ‘the construction suggestions for a reason.’

 

[Tomfh]

I think it’s being a bit hard on the OP to characterise not cutting the beam as a reckless change to the design, when in all likelihood it was only shown as cut because it was assumed it couldn’t come in one piece.

 

[XR250]

difference is 5/8 / 1/2 or 12.5 percent if continuous.

It is actually 25% total IIRC.
34x34 should work fine if 24x24 worked for simple spans. I agree, this Engineer needs to check his math