PMR06
Structural
- Nov 3, 2005
- 432
We have a project in house to design steel stairs for a building that was designed by others. The building is a school located in a high seismic region: SDC D, special moment frames, site Class E, and high importance. As I've been looking thru the structural drawings to figure out what our stairs will attach to, I've noticed several things I am not immediately comfortable with:
-Spread footings are not tied together directly or with any kind of detail to the slab on grade (RE: IBC 1805.4.2.2)
-Except for the RBS details, the connection designs were delegated, yet none have an axial component
-There are no details of diaphragm collectors. The only load path I see from diaphragm to moment frame would be thru joist seat rollover of the few joists in the frame bay, yet no load is given for the joist manufacturer to design for. This also presumes the last few puddle welds on the joist are enough to transfer that load.
-There are no diaphragm chords I can see. Perimeter edge angles are interrupted by columns, no add'l reinforcing added in slab, etc.
-Multi-story exterior CMU walls are called out “Per Arch”, do include a cookie cutter reinforcing schedule, but no detail of how they are tied back to the building
I'm not saying any of these things don't work, but there are enough red flags that make me wonder if the load path of this structure was really designed or just thrown together from a bunch of low seismic, standard details. I would love to send a simple, professional email to the EOR asking. I am not sealing our stair work, and the engineer who is reviewing/sealing this work (my boss) has instructed me not to pursue this. We are simply noting in our calcs the limits of our scope. He also jokingly asked that I remind him not to enroll his kids in this school…
Jokes aside, what responsibility/ethic/professionalism does a delegated engineer have when looking back thru design documents and seeing things that might not work, but are not related to the limited scope he was hired for?
-Spread footings are not tied together directly or with any kind of detail to the slab on grade (RE: IBC 1805.4.2.2)
-Except for the RBS details, the connection designs were delegated, yet none have an axial component
-There are no details of diaphragm collectors. The only load path I see from diaphragm to moment frame would be thru joist seat rollover of the few joists in the frame bay, yet no load is given for the joist manufacturer to design for. This also presumes the last few puddle welds on the joist are enough to transfer that load.
-There are no diaphragm chords I can see. Perimeter edge angles are interrupted by columns, no add'l reinforcing added in slab, etc.
-Multi-story exterior CMU walls are called out “Per Arch”, do include a cookie cutter reinforcing schedule, but no detail of how they are tied back to the building
I'm not saying any of these things don't work, but there are enough red flags that make me wonder if the load path of this structure was really designed or just thrown together from a bunch of low seismic, standard details. I would love to send a simple, professional email to the EOR asking. I am not sealing our stair work, and the engineer who is reviewing/sealing this work (my boss) has instructed me not to pursue this. We are simply noting in our calcs the limits of our scope. He also jokingly asked that I remind him not to enroll his kids in this school…
Jokes aside, what responsibility/ethic/professionalism does a delegated engineer have when looking back thru design documents and seeing things that might not work, but are not related to the limited scope he was hired for?