A New York high rise under remodeling is collapsing. From one of the photos, the corrosion is apparent, and too much of the steel is gone to hold the weight of the stories above. If the rest of the building is in such bad shape, demolition is probably the only solution, and I don't have any idea on how that can be done without damaging the surrounding buildings. In my opinion, it's too dangerous to attempt any work inside, and I wouldn't want to deal with the lawsuits soon to appear. I know I wouldn't even want to expose some of the steel at ground level to see its condition.
This article give some more information. The contractor has multiple violations, and the work involved adding additional stories to the building.
What gets my attention is the engineering involved. How can additional floors be added without careful examination of the existing structure? Regardless of engineering calculations for structural adequacy, if the original plans were used, they're basically useless. Structural steel design calculation are dependent on the sectional amount of steel, and the tensile strength. Corroded steel can't be calculated without a clear understanding of how much steel is gone, and whether the original shape used for calculations still applies. Considering what some of the pictures reveal, I can't imagine a competent engineer being willing to stamp the plans when a little examination would have revealed the degradation of the original structure. If I had to guess, some money was passed under the table, and a city employee is now in a world of shit.
I looked at the pic of the buckled column that was circulating. After I read your blog, I looked at it again, and yes the webs look rusted through in places and so do the flanges. But before it buckled, that column was coated with a fire-resistant coating, so any rust would not be apparent during a simple visual inspection.
ReplyDeleteThe rusting was due to years of water in contact with the steel, probably from an unnoticed leak. And you are correct! The property that engineers use To calculate the load, bearing capacity of a column of a given length is its minimum moment of inertia. If the flanges are majorly compromised, the buckling strength of the column precipitously drops. If the web is compromised, there is nothing to transmit the shear stress from the flanges, and they act independently Instead of as an H column. Someone has a big headache on their hands. You are probably correct that the whole building must be razed, piece by piece. The building, owner will probably go bankrupt and abandon the project. The insurance companies will probably be left, holding the bag up to the limits of the policies. So, the City will probably have to front the cash for demolition.
The next issue of Engineering News Record will probably have a complete analysis of this failure. It may be available sooner online.
One thing I'm not aware of is the correct procedure for analyzing the integrity of steel covered with fire proofing. I do know that if it's not correctly installed, it can defeat the purpose and lead to fire damage during a fire. I would think a detailed examination would have been required with a consideration of adding floors. Somewhere, an engineer is either not qualified, or easily manipulated, and their error will be costly.
DeleteIt's NYC, of course there is corruption in the unions, city, and state... sigh
ReplyDeleteAs long as there is fast easy money to be made standards and safety will be ignored.
ReplyDeleteI'd be concerned if it wasn't New York City.
ReplyDeleteThe final result will be a committee, some stern words, and it will be found the architect/engineer/project manager left the country...if they were ever here.
ReplyDelete