block unit masonry enclosure of exit stair
block unit masonry enclosure of exit stair
(OP)
I am checking the structural adequacy of some steel beams installed about 1995 to support a reinforced concrete flat slab floor where a hole was cut in the floor to enable the installation of an exit stair between several floors of a multi-storey office building, including down into the 2 level parking garage below. The exit stair is surrounded all sides by an 8" thick block masonry wall. I imagine that provides a 1 hour fire rating between the stair area and the adjacent floor (i.e. 2 hours between floors).
Question:
Would this most likely be normal weight concrete unit masonry, or lightweight concrete unit masonry? 8" normal weight hollow concrete block not covered by any finishes weighs about 58 pound per square foot of wall surface.
Question:
Would this most likely be normal weight concrete unit masonry, or lightweight concrete unit masonry? 8" normal weight hollow concrete block not covered by any finishes weighs about 58 pound per square foot of wall surface.






RE: block unit masonry enclosure of exit stair
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: block unit masonry enclosure of exit stair
Or, drill a hole and look inside the cavity with a borescope: I doubt the blocks are filled with concrete, but that would make a big weight difference.
RE: block unit masonry enclosure of exit stair
Thaidavid
RE: block unit masonry enclosure of exit stair
Both Normal weight and Lightweight are loadbearing. The Normal weight would give a 1+ hour fire rating and the lightweight would provide a 2+ hour rating if fire ratings were desired.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: block unit masonry enclosure of exit stair
Where did you get the 58 psf? That seems a little high for normal 8" Normal Weight or Lightweight units. Possibly unusual shaped units or if it was calculated, there must be some reinforcement and grout or just partially. There is such a thing as partially grouted masonry construction.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: block unit masonry enclosure of exit stair
To others: as to being grouted etc., I am certain this is not grouted because there is no reason for it to be. It is a 9 feet high interior wall forming the enclosure around an interior stair. The stair and enclosure (and hole thru floor and steel beams etc.) were installed in 1994 in a multistorey building built many years before that.
RE: block unit masonry enclosure of exit stair
I'd knock on some cells to be sure. I know several engineers whose minimum block wall is reinforced with 15M @ 1200 regardless of demand.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: block unit masonry enclosure of exit stair
RE: block unit masonry enclosure of exit stair
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: block unit masonry enclosure of exit stair