July 2016

SAHC and Don

by Don Friedman on July 30, 2016

My paper at the SAHC conference concerns a broader and vaguer topic than Marieta’s. Thorough analysis of an old building can give reasonably precise guidance¬†about load capacity, but what do we do for a fast answer? In other words, engineering analysis and design is often iterative and how do we get a rough idea of the capacity of, say, a steel column from 1910? Here’s the 1901 New York City Building Code on steel column design [as always, click to enlarge]:

The Building Code of the City of New York - Unknown (dragged)

Those values show a straight-line formula, where the allowable stress is reduced linearly from the allowable compressive stress in a flat piece of steel. (Longer columns have lower allowable stresses because of the possibility of sideways buckling under load.) My paper compares the allowable stresses in steel columns from 1900 until the present, in an effort to develop some simple rules to allow comparison of steel columns designed under old codes to the capacity that current codes give us now.

SAHC and Marieta

July 29, 2016

Six weeks from now, the tenth international conference on the Structural Analysis of Historic Constructions will take place in Leuven, Belgium. This is a conference devoted solely to the structural engineering aspects of conservation. I’ve both enjoyed and learned from the four previous conferences I’ve attended, including two years ago in Mexico City when Gabi […]

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The 1916 Zoning Law

July 28, 2016

It’s the hundredth anniversary of New York’s first real zoning law and there have been some good write-ups, for example in the Times and on Curbed. David Dunlap’s article in the Times is absolutely right that the typical story of the zoning law is oversimplified, but I want to take that idea in a different […]

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New York and Energy

July 27, 2016

The short version of energy use in New York City is a bit confused: lighting buildings at night and air-conditioning everything in sight seems wasteful, while the apartment- and transit-heavy nature of the city saves a lot of energy over the more typical American pattern of single-family homes and car transport. The long version is […]

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An Explosion Long Ago

July 26, 2016

The New York Times had an article today with a good capsule history of the Black Tom explosion, a huge event 100 years ago this coming Saturday. Informed opinion on the explosion has gone from “it must be German sabotage” in 1916 to “it was mishandling of explosives and coal dust” for most of the […]

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A Technological System

July 25, 2016

Beautiful, isn’t it? That’s part of Pier 66 on the Hudson River. This pier was built as a float bridge, allowing railroad cars to be loaded onto barges to cross the river. (I was there to go to the John J. Harvey, but that’s another story.) The pier consists of three pieces: a short ordinary […]

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The John Street Church

July 22, 2016

It’s always nice to see a project building written up, even if it’s not our project under discussion. Curbed had a good description of the [third] John Street Church: here. And since no blog post is complete with a picture that is either beautiful or confusing, here’s a picture that’s not beautiful: That’s the ridge […]

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In Plain View And Still Obscure

July 21, 2016

I was walking between two meetings in the Bronx yesterday and came across a random and interesting structure: The neighborhood (the lower part of the Grand Concourse, at the corner of 149th Street) is Mott Haven, but I had not heard of Mott Avenue before.¬†A few moments of googling turned up that Mott Avenue was […]

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Curtain Walls – Philosophy and Reality

July 20, 2016

The development of skeleton frames in the late nineteenth century made curtain walls – exterior walls of buildings that don’t carry structural load – theoretically possible. There was little precedent* for this type of wall and it attracted architectural theorists…a path that eventually led to the all-glass wall first as a theoretical concept and then […]

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Historic Structural Detail: Triangular

July 19, 2016

We see draped-mesh floor slabs all the time. They were the best solution to the problem of creating a stable, strong, fire-resistant floor for steel-frame buildings from the 1910s into the 1950s. Usually the mesh is similar to modern steel-wire mesh except that the old mesh was asymmetrical, with heavier wires at a closer spacing […]

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