Mixing ASD and LRFD
Mixing ASD and LRFD
(OP)
I am currently looking at a project to help out one of my customers who is a fabricator.
They have a project that they say is "simple" but things in this business are never simple. The building they need some assistance with is a new building designed by what I would consider a world class engineering company. My client needs me to design some of the connections for the building. In going through the plans to define my scope of work I noticed that they have specific notes on the drawing that say shear reactions are given at the working stress level and that moment reactions are given at a ultimate strength level. It is up to the connection design engineer to run the equations through some formulas in order to combine them together.
Am I behind the times in how buildings are designed nowadays? What would be the purpose to list reactions on a project it two different forms? This seems like they are purposely introducing confusion into the equations.
They have a project that they say is "simple" but things in this business are never simple. The building they need some assistance with is a new building designed by what I would consider a world class engineering company. My client needs me to design some of the connections for the building. In going through the plans to define my scope of work I noticed that they have specific notes on the drawing that say shear reactions are given at the working stress level and that moment reactions are given at a ultimate strength level. It is up to the connection design engineer to run the equations through some formulas in order to combine them together.
Am I behind the times in how buildings are designed nowadays? What would be the purpose to list reactions on a project it two different forms? This seems like they are purposely introducing confusion into the equations.






RE: Mixing ASD and LRFD
Seems very strange to me. I can think of no reason other than perhaps the moments are the basic seismic moments (1.0E) and everything else is gravity done with ASD.
RE: Mixing ASD and LRFD
In delegated engineering design that I've done, I've generally followed the method used by the EOR for the structure...and sometimes it is dictated that supplementary designs be done in a particular manner.
RE: Mixing ASD and LRFD
I don't even know if I can meet the fabricators schedule on this project. They always try to cram these things down my throat.
RE: Mixing ASD and LRFD
Either way, you're asking for trouble if you try to figure out what they want and move forward. If you guess wrong, you'll wind up redoing the work, delaying the schedule, and incurring more cost that might not be recoverable. If it gets to that point, steel could already be fabricated, and nobody will be happy.
I suggest you sumit an RFI to the engineer of record clarifying exactly what the requirements are. It should be either ASD or LRFD, not a mixture of the two.
RE: Mixing ASD and LRFD
BA
RE: Mixing ASD and LRFD
It's not a large project. Just two stories. I can't see multiple people working on this project at the same time. I am very disappointed in the engineering company with the way this is being presented. Out of school, I wasn't up to "snuff" when I interviewed with the company. Oh well.
RE: Mixing ASD and LRFD
RE: Mixing ASD and LRFD
RE: Mixing ASD and LRFD
No, no where near as large as TT..... but people would know them if I gave their name so we will leave them out of it.
RE: Mixing ASD and LRFD
Good luck figuring it out. Hopefully the EOR gives you some good direction.
RE: Mixing ASD and LRFD
RE: Mixing ASD and LRFD
RE: Mixing ASD and LRFD
With a conversion factor it does not require any additional connection design time.
Now with moment frames %gravity and %lateral moment information may eliminate some column web doublers.
www.FerrellEngineering.com
RE: Mixing ASD and LRFD