Contractor calls about construction loading 6

[AggieYank]

"We just want to verify we can use a scissor lift on your slab"

How do you usually handle it when contractors call to make sure they can use a lift / forklift / other machine on your slab, either on grade or suspended?

We have basically said yes in an extremely roundabout, no liability way, assuming it seems reasonable, but I'm curious as to how others handle the calls.

 

[JStephen]

mrengineer- there was a thread on your question some time back- do a search for it. I think the general concensus was that they would charge if they did it.

 

[DRC1]

So, if I understand this right, designing the building to accomidate construction, such as wheel loads, scaffolds ect. that will be required is a whole lot of work, so the designers don't do it. So the whole strucure gets designed with out any consideration of a process that every one knows will happen and says this is sombody else's problem. Let them accomidate their work to my design, and I will blythely ignore the fact that somebody will need to put loads on my structure. They can figure it out by themselves with out any calculations cadd drawings or support from us. And if somebody wants to know if this will support his equipment, lets bang him for all we can. Do you wonder why other members of the construction team may not see you as team players?
As some of you have figured out and some of you have not, We are all building the same structure for the same client, the owner. I am not suggesting that upon completion of the design you gratuiosly take on all the design functions for the contractors. But knowing that equipment wil be needed, you could give guidelines to what can be put on the slab after say 7 days vs 28 days. Other construction considerations can be incorperated in the design and guidelines set in the contract documents. This would not be free but would be billed to the owner as part of the design. What would the owner get out of it? by having these details, contractors could more accurately plan their work resulting in better bids. There would be less time lost worring about details such as lifts, becuase invariably some of these questions come up at the last minute and it is a fire drill in order to keep the project moving. Thus by eliminating these questions the job flows smoother.
I know I may have been baiting a bit, but it never fails to amaze me that we believe that the design and construction of any structure is two seperate and isolated functions. Guys we are different instuments in the same band.

 

[Qshake]

DRC1 - you've captured the very obvious - good for you. what you've failed to capture is that through decades design engineers have been the target of attack by contractors who believe that by looking at the construction process and tailored our design we have limited their means and methods. As a result, the contractor sues the engineer and owner stating he cannot build such a structure at the price bid. And once the engineer has burnt his hand on the hot plate he's not at all looking for a reason to burn it again.

So looking a bit more at this situation it is not that we are ignorant of the construction loading or that we maliciously refuse to be of help, it is a matter that was decided by the court of law many decades ago and is certianly being upheld on occasion to this very day.

In my opinion, the contractors have a lot more responsibility for being in their current position with respect to construction loading than you're presently giving them.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[swivel63]

well, for concrete buildings.....aren't floors fully shored for like 3 (maybe more) levels down, thus effectively distributing the load? so while some of the largest loads would be felt during the construction phase, aren't they are also given extra help as well?

 

[Loui1]

JAE,
I see your point of view, but think you're making a mountain out of a molehill for something like a scissor lift. If you go conservative and document correctly, doing this yourself will save yourself money and liability issues in the long run.

I'm not the contractor's favorite guy out on the jobsite, but he repects my decisions and recommends me to others. Asking for an extra on something like this will give you the reputation of a nickle and dimer. Typically, thats not a good image to portray to the construction community unless you're really that good and people are begging to work with you.

Proper judgement must be used. If they plan on placing a crane up on an elevated slab, then yea, you probably have a point in asking for money or telling the contractor to go ask someone else, but not for something fairly straightforward as the original post describes.

 

[archeng59]

Loui1, I respectfully disagree. Contractors frequently ask for additional fees for services not included in their original construction costs. If contractors are allowed to ask for more money to cover additional services, regardless of the quantity of work involved, why should engineers not be allowed to do the same thing? If you have our car repaired by a mechanic and he performs the repairs as directed for a fixed fee, you cannot ask him to do additional repairs at no extra cost to you. giving away free engineering is why the structural engineering fees are so low overall. Contractors and owners expect it because they believe we should perform pro bono work if we want to get future design work.

 

[swivel63]

i agree with loui1. the contractors i've worked with have swallowed the cost on our mistakes and it's just natural to help them out in a pinch. while not all contractors are like this, many are. the difference between your analogy and an contractor/eng. relationship is that the mechanic is working FOR you, not WITH you. in my experience, i'm working WITH the contractor to get a building built FOR the owner. and sometimes pro bono work for something minimal and small WILL get you future work because of your personal integrity.

 

[AggieYank]

DRC1, it's impossible to know what scissor lift they'll use, or if they'll use one at all, though it's likely. Let's assume that they'll use a 4000 lb lift during construction. Do we then design our slab for a 1000 lb wheel point load and say on our drawings that they can use a 4000 lb lift? What happens if the lift is only 2 feet wide? Then we'll have a 2000 lb point load over a 2 foot width, quite a bit higher than our actual design. Or what if the lift has a footprint that matches our joist spacing, say 3' on center. Then this lift will be putting a 1000 lb point load at midspan on either side of the support (joist). Can our slab handle this "extreme" negative moment? Every call I've had about scissor lifts has been different it seems. Weights from 3000 to 4000 lb with all different footprint dimensions on the lifts.

You could also consider pallet loading, temporary shoring for deep concrete beams / walls, etc.

Designing for every temporary construction load would limit the contractor to the means and methods you've decided upon, which would almost definitely be more expensive and less efficient than what the contractor may choose, based on his expertise and experience in his field, not to mention what is available to him. Only if you're working alongside the contractor in a design/build atmosphere would this be a good idea. It's my guess that even in design build, temporary construction loads are designed for as the project gets close to that point, and not upfront in the design process.

The alternative would be to design your building for the worst case possible scissor lift, forklift, pallet loading, etc, to not limit the means and methods of the contractor, but you'd end up with a building that costs 50% more than it should.

 

[SperlingPE]

Mistakes/ommissions by the engineer and construction mistakes by the contractor are completely different from means and methods of construction.

1. Means and methods are typically not part of the EOR's contract. Insurance carriers will scrutinize any work done that is not contractually required.
2. The amount of time it takes to do a loading check is irrelevant. It is still giving away engineering services. Respect the engineer enough to pay for legitimate work. Respect a contractor enough to pay for legitimate work.

Working with a contractor to solve problems that arise during construction (design ommisions / contractor mistakes) are most certainly a part of any job.

 

[Loui1]

The amount of $$ to increase the structure to accomodate these construction loads > the amount of $$ the contractor passes on as savings to the owner. Therefore it's not typically done unless the owner is the contractor.

I agree that it's giving out a free service, no doubt about it. Though, unless some unified organization bands us structural engineers together so we all do it and it becomes commonplace, then I "could" make a stink about it to the contractor. But as we all know, that isnt the case and I have to worry about the next project. Therefore, that is why I push my pride to the side and take 5 minutes, go conservative, and give the contractor an answer. If it doesnt work by conservative methods, then I tell him it wont work and they almost always have no problems about it.

Do you charge for analyzing baseplate slotting too? What misplaced auger cast pile groups? The list goes on.

 

[DRC1]

Maybe this would be a good topic for a new thread. If I baited some of you into a response I apoligize. However, there is an interesting question of how much should the designer consider the constructon process in his design and how should that be conveyed to the contractors. I think everyone who has been involved in this thread has a unique and interesting viewpoint on this topic.

 

[JAE]

We once had a small project, a pre-engineered metal building, in which we were the Architects and Engineers of Record.

The construction started up and things initially went well, but very soon after we started getting all sorts of calls from the contractor. The superintendent just wasn't very good. Anchor bolts were bent, some were in the wrong place. Footings were placed in offset locations. There were perhaps six to 10 problems that we had to fix.

In all of these situations we responded for the best interests of the Owner, our client. We sketched up fixes, visited the site, took photos, explained to the on-site super what was required in the plans. Basically we went the extra two miles.

After about a month of this we started complaining to the superintendent and to his project representative/manager that this was getting out of hand.

Next day we get a message from our president that the contractor was coming over to our office to discuss how we weren't behaving in a "team" manner. The president of the construction company, his VP, his PM, and some of the superintendents all showed up. We sat down in our conference room and the president of the construction company began complaining that we weren't responding fast enough to their RFI's and other requests.

Needless to say, we were quite P.O.'d. After the guy finished, I responded that I appreciated team effort, but fixing four to five field mistakes, all free of charge, to me - represented a very high level of Team effort.

Our architect PM also responded that in his experience he found that whenever there was a mistake or field error by the contractor then - boy - we should all be a team and pitch in to make it right. But if there was any sort of error on the A/E plans then the contractor immediately charged extra for the cost. This wasn't very team oriented at all.

The president of the construction company hadn't heard that there were numerous field errors that we had fixed for them without charge. We could tell that this was all new to him. He glanced over at his people and got up, said, "sorry to have bothered you - you are right" and left...his people following with, I could swear, tails between their legs.

This seems to happen a lot with poor quality contractors - there is a disconnect between the construction company leaders and the field personnel such that we A/E's sometimes get painted with an unfair brush by the field folks. And this leads to a lack of team attitude on everyone's part.

This isn't directly associated with this thread, but does go to show that simply offering the contractor free engineering help doesn't always make it to the top of the contractor organization, and as a result can eliminate any good will that you intend by offering free services.

 

[Qshake]

JAE - Don't you just love that one way "partnering"! Gosh I've seen it so many times. I'm glad you had a positive experience from it, I never seem to because at that time no matter whose fault, it's time, time, time and your the one holding the RFI....

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[mitchelon]

Folks,

I’m with JAE and those who have said that means and methods are the responsibility of the contractors. Liability is the word here. I would agree to review the calculations of their construction ENGINEER, but even then, I would not approve the use of the fork lift. I would either review or disapprove.

 

[whyun]

JAE, especially memorable words from your post are in the first sentence: small project.

Even when dealing with good and reputable contractors, consulting engineers still have to put the guards up these days. Haven't seen much favors being exchanged between companies lately.