Column on Double Layer Brick Wall

[Eng_Struct]

Hi All,

I just wanted to get some opinions /ideas on how to best support new penthouse roof column on top of an existing double-layer brick wall. The wall is currently supporting roof joists and the new columns fall direction above the joists spacing based on architectural layout. I am thinking of providing a "sill beam" on top of the wall bridging over the joist support and welding the beam to a wall plate on either side of the column/joists centerline. The wall plate will need to be anchored into the wall. The column will also resist lateral wind load. Any watch-its in this "sill beam" appraoch? I have provide a sketch below for the condition.

Note that the metal deck will need to be trimed back to be able to place the beam on top of the wall. Once the beam is installed, the metal deck will be extended to the web of the sill beam and rest on top of the bottom flange on one side.

 

[HTURKAK]

I would prefer RC perimeter tie/sill beam.. You are not supplying a lot info. here.. Some questions ;

- If the foreseen penthouse will be occupied space, the joist loads will change ..

- existing deck should have a slope .. what is your plan to make horizontal?

- what will be the new floor ? composite deck ?

- is this at a high seismic zone?

Apparently , the existing bldg. together with new penthouse shall be redesigned for new gravity, wind , seismic ( if applicable )loads..

my opinion..
















I cannot give you the formula for success, but I can give you the formula for failure..It is: Try to please everybody.

 

[Eng_Struct]

@HTURKAK

1. Yes the joist loads will change and the joists are to be reinforced for the new loads.

2. Tapered insulation is used for the roof; the framing is not sloped.

3. The new floor will be a metal deck with a checkered plate on top.

4. It is not a high seismic zone.

5. The existing building already has a penthouse and we are just extending the penthouse to a perimeter wall on two sides. The wind loading is not going to change much except the gravity. The existing building columns and roof framing will be reinforced for the new gravity loads.

I guess an RC beam can work at the brick wall location however how do you suggest the RC beam tie to the brick wall below?

 

[kipfoot]

If you're able, consider asking for a portion of the top of wall to be opened up so that you can see the condition. I think that would help you develop a detail that'll work in the field like you hope. (For example, if they have an angle that catches the edge of the deck between joists, then the deck probably doesn't also sit atop the wall and you won't have to cut it back)

I don't like: it's tough to get a satisfying connection to the existing wall. However, with a 10" double wythe wall, you'll perhaps have a wide collar joint where you can grout or epoxy bars, threaded rods, or studs welded to the bottom of a plate.

I like: a continuous W shape solves the issue of how to place the column directly on the joist bearing, but also lets you model the column with a fixed base connection, which may be key to justifying the skinny columns that the architect is probably showing.

 

[BAretired]

Use a concrete pad large enough to spread the load using a conservative bearing pressure. No need to use a continuous beam.