Existing brick pilaster carrying capacity 4

[projectrcl]

I'm analyzing a 100 year old brick building's pilaster load carrying capacity. The building is 4 stories high with 20"x20" brick pilasters at 13' O.C. Brick exterior wall is 12" thick. Building owner wants to add more floors on top. Building sits on bed rock, test pit reveals spead footing of 32"x32" below each pilaster.

Can anyone recommend the following without destructive testing of the pilaster:
1. Allowable bearing stress of the pilaster (Fa)
2. Building's in New York City with light seismic activity, what might be a safe lateral allowable shear stress of this pilaster (Fv)
3. Bending (Fb)

To arrive at a final design for ultimate carrying capacity of this pilaster what steps should be taken (incl. extracting brick and mortar for test)? I don't know whether the pilaster is reinforced or not.

Thanks for your helps guys.

 

[kelowna]

In this forum, in good faith and with the information available, I do not think anybody can give you the figures you are looking for.

I guess the client hired you to find out exactly that. If you have a specific question about how to go about to find it, you would probably have better responses.

I would certainly recommend taking samples and finding exactly what those columns have inside before going any further

 

[ToadJones]

Maybe encase the pilasters reinforced concrete and enlarge the footings below.
Expensive, I know, but a sure thing.

 

[vandede427]

based on my knowledge the IEBC (not sure if NY state has a bldg code for existing structures), you're probably not going to be allowed to add stories to that structure and still use the original vertical and lateral systems.

increase seismice weight by more than 5% and modify more than 30% of the total floor/roof areas, then you've got to bring the bldg up to current code.

 

[abusementpark]

Dealing with existing brick is very frustrating. It's very hard to find any sort of guidance for nominal values on connections.

 

[bridgebuster]

You can download the 1901 NYC Building Code at:

http://www.archive.org/details/buildingcodeofci00newyrich

 

[vandede427]

I downloaded that document........amazing. I felt like i was watching National Treasure with Nicholas Cage.

The section on brick requires it to be "good, hard, and well burnt." Nothing more, nothing less. It allows the use of lime mortar (which you better hope isn't the case in your building).

Page 118 starts the section for allowable stresses.

On page 75, it lists the penalty for placing any item on a fire escape platform "ten dollars and imprisonment for ten days."

Page 120 specifies 30 psf wind for the full height.

This is truly amazing. I could spend hours looking at this document.

 

[BAretired]

On page 115 of the 1901 NYC Building Code, the safe bearing load to be applied to brickwork shall be taken at eight tons per superficial foot when lime mortar is used; eleven and one half tons per superficial foot when lime and cement mortar is used; fifteen tons per superficial foot when cement mortar is used.

BA