Pre eng pre fab metal bldgs
Pre eng pre fab metal bldgs
(OP)
Are pre Eng Pre Fab Metal buildings cheaper over standard
construction?
construction?
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
Download nowINTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
Pre eng pre fab metal bldgs
|
Pre eng pre fab metal bldgsPre eng pre fab metal bldgs(OP)
Are pre Eng Pre Fab Metal buildings cheaper over standard
construction? Red Flag SubmittedThank you for helping keep Eng-Tips Forums free from inappropriate posts. Reply To This ThreadPosting in the Eng-Tips forums is a member-only feature.Click Here to join Eng-Tips and talk with other members! |
ResourcesWhat is rapid injection molding? For engineers working with tight product design timelines, rapid injection molding can be a critical tool for prototyping and testing functional models. Download Now
The world has changed considerably since the 1980s, when CAD first started displacing drafting tables. Download Now
Prototyping has always been a critical part of product development. Download Now
As the cloud is increasingly adopted for product development, questions remain as to just how cloud software tools compare to on-premise solutions. Download Now
|
RE: Pre eng pre fab metal bldgs
A strong advantage of standard construction is that a building can be easily customized to fit the need of the consumer.
Nathaniel A. Manges, E.I.T.
Structural Engineer
RE: Pre eng pre fab metal bldgs
The disadvantage of a MB system is simply that some types of structures are too heavy duty to be a metal building. For example, nobody would try to make a 5 story office building or hospital out of one. Wouldn't do that with wood either.
RE: Pre eng pre fab metal bldgs
If initial cost was the only factor, we would all be driving Yugos.
Don't get me wrong, we use a lot of PEMBs. But your job is to make sure the end user gets exactly what they want, which isn't always the cheapest.
RE: Pre eng pre fab metal bldgs
A lot of people seem to think they can have a normal building clad in brick and beautiful finishes and just because it's a PEMB it'll be cheaper. That's not the case.
RE: Pre eng pre fab metal bldgs
RE: Pre eng pre fab metal bldgs
namanges
RE: Pre eng pre fab metal bldgs
We received several calls from the January ice storm in the midwest and this months ice storm. Between the two storms we have looked at 23 buildings that collapsed, every single one was a PEMB. The mnfr’s state that the loads from ice and snow are above code loads and that is why they failed. They are correct, but I must point out that we have not inspected a single block and bar joist that failed under the same loadings.
If a building is designed for a LL of 20 psf it should not fail at 23 psf, unless it is a PEMB. A PEMB done correctly is a great building, however I would offer these tips when ordering one.
1) Add 10 psf to the code minimum LL or SL, do not allow any reductions.
2) Don’t use the PEMB DL of 2 or 3 psf, the owner will also add more.
3) Make sure the main frames are designed to handle a point load if the PEMB. We inspected a 40,000 sq ft building that collapsed because they attempted to lift a 700 lb engine out of a Ford with the hoist attached to the main frame.
4) Do not add a mezzanine or 2cd story, many PEMB mnfr’s software programs can not handle this and they hire a real Structural Engineer to design it for them.
5) Stay away from small mom and pop operations if it is going to be a commercial building.
6) Get in writing that if one purlin fails the main frame will not.
7) Double check wind and seismic calcs.
8) Make sure you have wet signed and sealed plans and calculations.
9) Require the mnfr to inspect the building upon completion and sign off of it.
Next time you complain about the changes to ASCE 7, just remember this. Most of the significant changes to the building code came because of all the failures that PEMB had when first introduced. Just look at the early building sketches in all the codes.
RE: Pre eng pre fab metal bldgs
RE: Pre eng pre fab metal bldgs
RE: Pre eng pre fab metal bldgs
You make a lot of good points in your post. I'd personally adopt a few of your bullet points if I were to specify a MB, especially #5. I dare say that that would fix most or all of the others.
However, there's no reason to be down on the manufacturers. Owners almost universally want the cheapest possible structure when they come looking for a MB. MBMs provide what the owners want. If they don't, then the owner will find someone who will. Blame them if there's a desire to blame somebody.
If someone wants a beefier building, he can do as you recommend--higher loads, etc.
RE: Pre eng pre fab metal bldgs
271828 is correct in that each building is designed individually and that the PEMB manuf’s are just supplying what the owner or the owner’s rep. asks for. There was an article in Modern Steel Construction several years ago where the writer (an engineer) complained because a top running crane could not be added to an existing PEMB without adding reinforcing the frames. Well, duh. If the owner had the foresight to know that a crane was to be added, then the building could have been designed for it. Why increase the initial cost of the building if the owner has no plans for a future crane? Or mezzanine? This also goes for beefing up columns where forklifts will be operating or something similar to that.
BRGENG makes several good comments. However, I am not aware of any large PEMB manuf. that cannot correctly design a steel building with a 2nd floor or mezzanine. They all employ plenty of “real” structural engineers that can modify their software or use RISA, Staad, RAM, etc. Also, for a 40,000 sq ft steel building to collapse because of the addition of a point load would be highly unusual, unless there was already 150% of the design roof snow on the building. Because of the inherent ductility of steel, PEMB’s, like other steel buildings, allows loads to be transferred from damaged areas to undamaged areas without collapse. And no properly designed PEMB should fail under a 23 psf roof load if the design load is 20 psf (see note above about businessmen and brother-in-laws). His point about the flattening of the purlin lips is correct. Cold-formed steel is a funny animal. Field modifying the shapes can produce significant reductions in the capacities. All of the manuf’s that I am aware of note this on the drawings and show how hangars should and should not be attached to purlins.
PEMB’s have their market and it is expanding. However, I don’t want metal panels on my house.
And speaking of house, that’s where I’m headed. Everyone have a Merry Christmas!
RE: Pre eng pre fab metal bldgs
“It is recommended that the foundation of the building be designed by a Registered Professional Engineer experienced in the design of such structures.”
Typical note seen on every set of plans, but not what the advertise.
Luckily for the client the PEMB mnfr salesman stated in an email that a Structural Engineer would not be required, they might be able to get my fees paid by the PEMB mnfr. The client called the PEMB mnfr after hearing their commercial on the radio. And there lies the problem, PEMB is a very competitive business with a very aggressive marketing campaign. They often market directly to the owner who are not educated enough to understand what they are ordering from the PEMB. You should always consult with an Architect or Engineer before starting a project, but the PEMB mnfr wants to get them under contract before contacting the consultants. They will promise them a building at half the cost of convention construction. Based on interior columns, 28 gage metal, cheap roll up doors, short warranty’s if any, etc. and anything else to lower the price. Then they change order everything out that the Engineer or Architect specify and in the end the savings are not there.
I have dealt with PEMB companies for over 25 years, I wrote the design programs that many use in their office. I believe they have a product that is great in certain situations but is terrible in others. I seen to many clients regret building a PEMB, and the longer they are in them the more often they regret them. This applies to churches, schools, shopping centers, etc. My industrial clients love PEMB and would never consider anything else.
RE: Pre eng pre fab metal bldgs
The major players in the PEMB industry are represented by the MBMA. See the March issue of Structure magazine for an article written by MBMA which states the case for why an owner should hire an Engineer of Record, such as yourself, when using a metal building.
RE: Pre eng pre fab metal bldgs