brick pier - fm renovationaddition in nyc

huangyhg

brick pier - f'm? renovation/addition in nyc
our firm recently started a project out of nyc that proposes adding 2 stories + a roof to an existing 4 story building.
the construction of the building is a mass brick perimeter (with large piers) and an interior steel frame. there are interior built-up steel columns and all of the steel beams framing into perimeter girders which bear onto the brick piers.
i am charged with determining the mass brick pier capacities and i'm not sure what would be a typical f'm prism strength for such brick. the building was built very early in the 1900's. we need to determine if these piers can take the additional load, how much they may be overstressed, and a proper method for reinforcing them if that is the case.
please let me know if anyone has had experience with such design in the past.
*  does the brick appear to be sound?
*  do you have drawings of the original building?
*  are the piers solid or hollow?
*  can you have samples taken and tested to determine f'm?  
*  is the additional load significant?  
*  are the foundations adequate to take additional load?
if you need to strengthen the brick piers, you might consider the use of reinforced pneumatically placed concrete on the exterior.  this would add more weight to the foundation which may not be capable of carrying it.  
you will need a soil report in order to determine whether or not the existing foundation is adequate.
  
ba
i have not touched brick design in years but i have done a few rehab jobs in nyc and if i recall correclty, for a sound looking brick strucure i used to use a value of 1,200 to 1,500 psi for f'm.
try to get the applicable standards from the masonry institute??? (don't quite re  
maybe something is here:
quote (baretired):
can you have samples taken and tested to determine f'm?
i would do this.
keep in mind that in the early 1900's most masonry was used with high-lime mortar that was very soft (thus old brick structures don't need expansion joints like today).  
with old, soft mortar i'd get the real f'm if i were you.  assuming 1200 to 1500 psi may turn out to be oi per w12x26, but for two floors and a roof i'd do the right thing.
there should be areas of the walls where you can take out prisms - preferrably through the depths of the walls and not just on the outside.  interior brick in thick walls were sometimes just waste brick or even debris, sand and other junk that were used to fill between the outer wythes.