Civil \ Structural engineering question

[BrownTown]

So I am a student at Vanderbilt University and there is also the associated Vanderbilt University Medical Center (VUMC) which has ~10 buildings of 10+ floors. The interesting thing is they also have alot of shorter buildings and now they are doing vertical additions to some of these buildings where they add floors to the top. I was wondering how common it is to build vertical additions to existing buildings and how is it even legal to build on top of another building, wouldn't adding all that weight compromise the integrity of the building? I guess it makes sense on some where they build the buildign only 5-7 years ago and they likely just designed it to be strong enough to have extra floors, but one of these is 30 years old and just got 4 extra floors from 8 to 12 stories tall.

Examples:

-8 story building going to 12 stories (30 years old)
-4 story building going to 15 stories (ring of columns build around the sides explains this)
-2 story building going to 12 stories (originally build 5 years ago, no additional columns added, but I assume they built them in 5 years ago)
-4 story building going to 12 stories, built 20 years ago, no new columns added (this one is totally crazy imo, or did they plan this out 20 years ago?)

 

[Howard]

Why is it impossible that old buildings were excessively overbuilt?

 

[FleshLight]

Well it certainly is legal provided that you have the proper permits. The factor of safety can go down with the additional allowable stress but as long as it's an acceptable decrease, then it's fine.

 

[Epic Fail]

Don't worry, the doctor is there if the building fall down.

 

[BrownTown]

Originally posted by: yamadakun
Don't worry, the doctor is there if the building fall down.

No, i the building falls down the doctors are all dead

 

[Howard]

Originally posted by: FleshLight
Well it certainly is legal provided that you have the proper permits. The factor of safety can go down with the additional allowable stress but as long as it's an acceptable decrease, then it's fine.

If by "allowable stress" you mean "load", then yes...

 

[Savij]

Which buildings are they adding floors to?

 

[bctbct]

Many building are built for future expansion. If they are building you can rest assured that engineers have spent thousands of hours researching the construction.

 

[BrownTown]

Originally posted by: Savij
Which buildings are they adding floors to?

FWIW:

MRBIV
That one is the 4 new stories over 8 existing (left side of picture) and the 10 new stores over 4 existing (right side of picture).

Third Bed Tower
OK, this one is more complicated, on the far right you see the current "second bed tower" which is 12 stories tall and looks like the letter "X" in the middle is currently the 1 story emergency department which was added ~5 years ago, on the far left is currently a 4 story building. Basically as you can see they are building up on top of the 1 and 4 story buildings to bring them up to the same height as the 12 story building.

Some additional projects, they include adding another 6 stories on top of a 4 story building and adding a 3 story garage on top of another 3 story garage.