Built-Up Lattice Column Repair
Built-Up Lattice Column Repair
(OP)
All,
Client has requested repair of existing column (top two floors ~20 feet) at facade of building on Upper West Side in NYC. (See attached photo). Column consists of two (2) channels with lattice bars. The bars are severely corroded, as are the flanges of the channels. The web has about ~50% section loss, but we won't know for sure how much steel is left until we clean the steel. The spacing between the channels is approx. 4". Since we cannot weld to the flanges, any recommendations or suggestions on reinforcing or replacing this column as well as repairing the connection of the spandrel beam to the column? Thank you.
Client has requested repair of existing column (top two floors ~20 feet) at facade of building on Upper West Side in NYC. (See attached photo). Column consists of two (2) channels with lattice bars. The bars are severely corroded, as are the flanges of the channels. The web has about ~50% section loss, but we won't know for sure how much steel is left until we clean the steel. The spacing between the channels is approx. 4". Since we cannot weld to the flanges, any recommendations or suggestions on reinforcing or replacing this column as well as repairing the connection of the spandrel beam to the column? Thank you.
RE: Built-Up Lattice Column Repair
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: Built-Up Lattice Column Repair
Have you thought about concrete encasement? Your building may not like the additional mass, but it is a potentially very effective and simple repair. Clean the existing steel, provide new bars and stirrups, pour new columns.
If you are dealing with a heritage condition you may find your situation further complicated by what will be acceptable to the HAHJ.
RE: Built-Up Lattice Column Repair
Looking at your conditions, I really think full replacement or concrete encasement are the best options. Potentially add a cathodic protection system to arrest the corrosion as well.
Please investigate all of the lower floors. I have a hard time believing that such advanced corrosion is confined to the top two floors, which I presume are the ones which were exposed during other works.
RE: Built-Up Lattice Column Repair
I personally like to clear an extensive area to "free from lose" condition, and several localized areas to white steel prior to the final evaluation... Widespread deep pitting can be quite shocking in these situations, and can also make it very hard to get a good estimate of the net area of remaining base steel.