Construction History Society of America at AIA Iowa

Digital reconstruction of 1851 Elijah Otis Patent. Courtesy Lee Gray

A phenomenal crowd this morning for a special Construction History session at the annual AIA Iowa convention–over 100 turned out for two fantastic papers that gave a taste of what the discipline is about.  Thanks to Lee Gray of UNC-Charlotte and Meghan Elliott of Meyer, Borgman, & Johnson in Minneapolis for taking the time to talk about their research.

Dr. Gray’s work covers early elevator construction, and he showed some amazing reconstructions of early patent drawings by Elijah Otis and Otis Tufts (what was it about the name ‘Otis’?)  By reconstructing otherwise impenetrable drawings in three virtual dimensions, Gray is able to show how these early mechanisms worked (or, perhaps, didn’t) and what they suggested as the field moved forward.  He’ll be on an episode of NOVA in November…worth checking out.

C.A.P. Turner's Four Types of concrete construction. Images courtesy Meghan Elliott

Meghan Elliott is a consulting structural engineer whose specialty over the last few years has been historic concrete structures in Minneapolis, and her work on C.A.P. Turner combines historic preservation and preservation technology with a practical interest in the larger historical context in which these buildings were constructed.  She’s presented at the first two CHSA Biennial meetings and her explanations of how Turner developed his ‘four-way’ slab system (you thought there could only be two, didn’t you?) give some real insight into the methods available to engineers and builders of the early twentieth century.  Turner’s design methodology involved extensive empirical testing, which proved to have important consequences; he tested his slabs fresh out of the forms, and it didn’t become apparent until too late that the natural cracking and creep that affects concrete had somewhat frightening consequences for long-term deflection.

Lee, Meghan, and I are going to reprise this presentation for the AIA Minnesota conference in early November–we’ve got a bit more time, so I’m going to add a brief summary of my plate glass research.  Many thanks to everyone who showed up this morning–it was a real pleasure to talk to such a large crowd!

monadnock II–masonry walls and bay windows

OK, continuing on from Monday’s post, here’s a plan of the Monadnock’s northern two bays–the ones designed by Burnham and Root and built in quick succession between 1891 and 1893.  What everyone notices, of course, is the thickness of the walls–this plan is from about the eighth floor, so the size of the brick piers actually gets much greater beneath this.  Note, too, the cross-walls.  There are two of them in the northern wing (to the right), but the southern wing relied more on internal, wrought-iron bracing girders and an elaborate network of diagonal rods buried within the floor plate.

Iron also played  a big role in the bits of cladding between the piers.  Most commentary on the Monadnock has focused on Root’s ability to detail the brick exterior to appear as a continuous, undulating surface, but even from the architectural plan you can see that the Monadnock was really two very different cladding systems in one.  The brick piers served both as enclosure and as structure, while the oriel windows were much lighter, shedding any structural load (carried, instead, by cantilevering wrought iron beams) and serving exclusively as light- and air-gathering devices.  (They also, of course, stole square footage from the air over the sidewalk).

The 1890 Pontiac Building, shown at left, was a contemporary of the Monadnock and one of the first (after the 1888 Tacoma, also by H&R) to use the oriel, or bay window, as an element in skyscraper skins.  Usually seen in residential applications, these bays provided greater glass surface area and better opportunities for views and ventilation.  But they were difficult to construct in masonry and cast iron structures, as the cantilevered floors within them required beams and girders that could take quite a bit of bending.  As steel began to find regular use in skyscraper construction, these cantilevered bays were slightly easier to construct.  The bays don’t show up on B&R’s 1885 scheme, but they practically dominate the structure as built; technology and materials had clearly changed between the project’s iterations.

Thus, while the Monadnock stands assuredly at the end of the city’s tradition of masonry skyscrapers, Root’s bay windows were far more progressive than the structure is generally give credit for.  The Monadnock’s bay windows represented an early use of a device that had been well-tested, but that would also find far greater application on the other ‘veneered’ buildings of the early to mid-1890s.  Rather than seeing the building as strictly a masonry structure,  we ought to see the Monadnock as a steel building struggling to break out of a masonry cage, and that makes it, I think, even more interesting than the traditional histories have suggested.

old skyscraper of the week–monadnock

I spent a month this summer at the Canadian Centre for Architecture studying their collection of over 400 Burnham and Root drawings for the Monadnock–one of Chicago’s best known 19th century skyscrapers and the building traditionally seen as the tallest and most complete statement of the masonry-structured skyscraper there or anywhere else.

What I found doesn’t so much contradict that traditional view as expand upon it, and while I want to save some secrets for the book (manuscript complete and in review as we speak), there are some aspects of the research that I think deserve some immediate discussion.  So I’m going to post a couple of bits this week on the building and its structure.

First things first: in addition to an immense debt of gratitude to all of the staff at CCA, I also owe big shout-outs to Bill Donnell, the building’s owner, who has now twice volunteered his time to show me around the building–including its basement(where you can see perhaps the only exposed grillage foundation on the planet) and some of its more intricate structural elements; and to Michael Blossom, a high school classmate and owner of the two Floradora boutiques on the ground floor, who let me poke around while he was having some renovations done.

So today, some basics.  The building was commissioned by Boston’s Brooks Brothers, who had previously hired Burnham and Root to design the hugely successful Monadnock Block.  In 1885, anticipating the opening of Dearborn Street to the south, the Brooks’ asked B+R to design a large block on the sliver of land left between Dearborn and what’s now Federal Place.  Root’s response was an expansion of the Montauk’s basic idea, but with brick structure organized into piers and window surrounds, adding a grain to what had been very neutral elevations in the earlier project.  With uncertain economics, however, the project was put on hold for several years.

In the runup to the 1892 Columbian Exposition, however, the Brooks’ realized the chance to develop what was becoming a prime piece of land, and they seem to have asked Burnham and Root to rush the project to completion in 1890-91.  Whereas the earlier scheme was rendered in immaculate drawings, the latter plans were clearly done in a rush.  Several competing myths suggest that Root either trimmed the ornament from this scheme because of the Brooks’ concern that it would cost too much, or that the minimal elevations were actually planned by Burnham while Root was on holiday, but more impressive was the fact that Root responded to contemporary developments in cantilevered steel construction and large, light-gathering bay windows.  These elements were grafted on to a stripped-down version of the original scheme, pushing the building’s rental spaces out from between massive weight-bearing piers of masonry.

Root’s detailing, of course, belied the casual mythology of the building’s aesthetics.  Several hundred custom sizes of brick were required to construct the building’s flowing, undulating brick elevations and the famed corner chamfers, a difficult fabrication and construction issue that shows Root’s concern that the building read monolithically, and as a definitive statement in brick.

The Monadnock was not just a brick structure, however, and its bay windows suggest that, rather than being seen as the final statement of masonry skyscraper construction, it might better be seen as a pivotal moment in the relationship between steel and brick.  I’ll post some diagrams and explain why I think this is the case sometime mid-week.