The largest project of my career has recently started construction.  Upon completion, the structure will be the tallest building in Cincinnati.  It will be an icon of the city’s skyline, featuring an exposed steel tiara inspired by Princess Diana.  It’s pretty exciting to tell people about my role in this exciting project.

Learn more about the construction progress at: http://news.cincinnati.com/article/20090119/NEWS01/901190345/1055/NEWS

However, big projects mean big stacks of shop drawings for the design engineers to review.  Shop drawings are detailed drawings that indicate precisely how each individual piece of the structure is to be fabricated.  They are drawn by meticulous engineers that work closely with steel fabricators, rebar suppliers, and other structural element producers.  Producing quality shop drawings ensures that every piece of the structure shows up at the job site sized and detailed to fit together.

On the other hand, structural design engineers, like me, put together drawings that give only the general specifications for each piece.  Our plans typically represent beams only as single lines on paper.  The detailers and fabricators have to interpret those lines and create actual 3-dimensional beams.  That’s where the shop drawings come in.  Before they actually start cutting the steel, the shop drawings are sent to the structural design engineer for approval.  This places quite a lot of pressure on the design engineer, because failing to review and return the shop drawings in a timely fashion can delay the project.

Reviewing shop drawings is a tedious and time-consuming task.  Each sheet is packed full of information.  During the initial design phase, the shape and size a steel beam itself is the main concern.  Steel shop drawings, however, must include much more information including: the number of bolts at each connection, the size of welds, the thickness of the gusset plates, the camber (upward bend), coping (cutting back a portion of the flanges to fit two beams together), location of bent plate pour stops, and much more.  Concrete rebar shop drawings are just as complex, because each bar, with all its bends and hooks, must be accounted for.

If mistakes are found, the reviewer has two options.  For small mistakes, the drawing can be approved as noted. This means the fabricator can review the comments marked on the sheet by the reviewer and proceed right away.  However, when errors are found that could have a serious impact on the structure, the reviewer would ask that the drawing be revised and resubmit.  This prevents the fabricator from working on the piece until the reviewer approves the corrected drawing.

Digesting all of the information on the shop drawing and correcting mistakes can take a long time.  Usually, I’ll find a rhythm after working through the first couple of pages.  Still, I find that I have to stop and take a break at least once an hour, so that I can maintain my focus.  For the past several weeks, I’ve been contributing about 20 hours per week to the mountain of shop drawings.  We have more people working on the project now than at any other time in the life cycle of the project.  That’s pretty typical for large projects.

As a design engineer, I don’t literally contribute any blood, sweat or tears to the building.  I think reviewing shop drawings is the greatest test of fortitude that I’m asked to partake during the project, which isn’t too much to ask.  The upside of carefully reviewing the shop drawings is that I do feel more intimately connected to the building.  Having literally reviewed the nuts and bolts of the structure, I’ll have a unique perspective of the structure.

Buildings are frequently generalized into two main categories based on their primary structural material, concrete or steel. In reality, most buildings are more of a composite construction – using concrete and steel both, where their characteristics can best be put to use. For example, almost all buildings have concrete foundations, owing to the economy of using concrete in compressive conditions. Likewise, almost all structural concrete is reinforced with steel bar, typically no less than 0.15% by volume.

Reinforced concrete (R/C) is also readily used to form columns, beams, walls and slabs. There are many advantages to using reinforced concrete as a total building system.

1. Concrete aggregate is almost universally available, leading to reduced material costs in remote locations.
2. Concrete is also fairly easy to work with.
3. R/C slabs require much less depth than a steel floor system. For a typical span of around 20 ft. a R/C slab would be about 8” thick; an equivalent steel floor would be about double the depth. This allows designers to add more floors while maintaining same total building height – a major advantage in cities with height restrictions like Washington, DC, where nothing may be taller than the Washington Monument.
4. R/C slabs can be supported by monolithically cast columns. This frees designers from having to place columns on a rectangular grid. This is especially applicable to residential developments with units of varied layouts. Designers may locate the columns in mechanical chases and other nooks and crannies hidden within interior partition walls.
5. In super-tall buildings, occupant comfort is often the limiting factor. High winds can cause a building to sway uncomfortably. Owing to the shear volume of concrete used in solid structural walls, concrete buildings tend to be stiffer and therefore less prone to uncomfortable motion.

In March of 2008, I began work on a 6-story concrete apartment building in Chicago. The architectural floor plan incorporated several different unit layouts, and the architects wanted to hide the columns out of the sight of the residents. A concrete structure permitted the necessary freedom in column placement. Also, a vertically oriented mechanical system limited the need for large ducts to cut across the ceiling. Therefore, the architects could take advantage of the short floor-to-floor height and save façade material and construction costs.

I made a few visits to the site to inspect the reinforcement layout. The structural drawings specify the size, length, quantity and location or rebar. Most slabs have a continuous bottom mat of regularly spaced rebar. A top layer of reinforcement is placed over columns and other areas of the slab that experience convex bending. Wire chairs are used to make sure that the reinforcement is placed at the correct depth. It’s important that all of the bars are properly supported and tied down, so that they’re not knocked out of place while crew places the concrete. This is a major concern when long tubes are used to convey the concrete to the pour location from the truck.

During my most recent trip to the site, I had the chance to watch the pouring of the concrete roof. A pump truck was used to lift the concrete up to the roof. The concrete then dropped straight down through a chute. An operator used a remote control to move the boom. Meanwhile, a team of laborers raked the concrete over the roof surface and into corners. There were a couple of workers with vibrators, which help the concrete consolidate into the forms. The biggest guys on the crew usually work the vibrators, which they carry around on their backs. Later, another set of skilled workers used screeds and fanning machines to level the surface of the concrete.

Building formwork and placing concrete is labor intensive. It can be backbreaking work, but only a few tasks require highly skilled workers. This makes cast-in-place concrete a very desirable building material for places with relatively low-cost labor. On the other hand, cast-in-place concrete is rarely used in countries, like Denmark, with very high labor costs. Fortunately, in Chicago, labor costs for steel and concrete construction are very competitive, so the building system is usually based on the architectural and engineering requirements of the project.

Over my holiday vacation, I read an interesting book about one influential architect’s thoughts on New York City.

This past fall, I also traveled to New York, for a leadership training seminar sponsored by my company.   I took this opportunity to stay a few extra days and explore the historic city.  From a friend’s apartment in Brooklyn (in a neighborhood strikingly similar to Sesame Street), my wife and I ventured over the Hudson River to Manhattan.  We may have experienced the city in a way similar to our ancestors who arrived in the New World via Ellis Island, in the shadow of the Statue of Liberty.

Some 80 years ago, one of the most revolutionary architects of the modern era entered the ports of New York for the first time.  LeCorbusier would revolutionize the notions of the modern city and architecture.  Upon arrival in the brand new city of New York (by Parisian standards), he was both in awe of the vertical city and aghast at the lost opportunities of utilizing the new American invention – the skyscraper.

In 1938, LeCorbusier began publishing a series of essays about his travels to New York.  The English translation of these combined works was translated and published in America in the book When the Cathedrals Were White.  The title is meant to show a parallel between the era in Europe when the renaissance masters were unfurling their beautiful Cathedrals and the modern era in New York where architects and engineers enthusiastically took up the task of engineering the city of skyscrapers.

The book is an interesting read because of and in spite of a perspective that seems dated some 80 years later.  LeCorbusier writes at length about conditioned air, elevators, and automatic doors, things that we take for granted today.  However, despite the time warp, many of his descriptions of the city remain true today.

Knowing that my prose falls far short of the master, I thought it would be interesting to use LeCorbusier’s words to describe the sights that I encountered on my own visit to New York.  I took each of the following photos on my recent trip to New York.  The captions are excerpts from When the Cathedrals Were White, by LeCorbusier, translation by Francis E. Hyslop, Jr., published by McGraw-Hill in paperback in 1964.

New York

Within the ring of its docks Manhattan thrusts itself up into the sky.  A great many skyscrapers fill the space, shut off the horizon.  I did not imagine that there were so many of them; I imagined a few examples of boldness and vanity.  But the whole city is vertical – or at least it seems to be, for a limited number of verticals succeed in taking up the blue of the sky. (p 88)

Brooklyn Bridge

Brooklyn Bridge, which is old (elevateds, cars, trucks, pedestrians all have special lanes), is as strong and rugged as a gladiator…  In this case the two large Gothic towers of stone are very handsome because they are American and not “Beaux-Arts.”  They are full of native sap and they are not graceful, but strong.  The vertical cables are black and not silver, but in perspective their vertical fall fixes a spidery veil.  It is an imposing architectural sensation; vertical, slender, immense, yes I come back to the immense and like a barbarian I enjoy it, or better, as a man animated by a constructive spirit, active but wearied by the depressing atmosphere of cowardice and abdication in Paris, crushed often dishonored, treated as a madman and Utopian consigned to the Greek calends, etc… here I find reality.  And it brings me a profound satisfaction

Reality, that is the lesson of America.  It gives our boldest speculation the certainty of imminent birth. (pp 77-78)

Wall Street

The bronze statue of Washington stands on the steps of the Sub-Treasury in front of the Doric porch; above are the rough-hewn early skyscrapers, rising vertically and making it a compact lap dominated by a gigantic chest of geometrically organized stones pierced by innumerable window squares against an endless extent of tangled surface of vertical shafts; the materials are varied, the crowning elements against the sky are in confusion….

… for those who are able to see, New York, projected violently into the sky, an outcry that you hate and love at the same time, hides in the bottom of its canyons of banks the architectural composition which is most expressive of the soul of the country.  An architectural scene variously put together, majestic, intense, remarkable.  The foursquare mask of Washington is at the exact point from which the tumultuous forces of architecture are set in play.  Proportion, quantities, relations, absolute mathematical rightness, radiance… (pp 73-74)

Central Park

The park is surrounded by fine buildings-apartment houses in tall blocks or in the form of skyscrapers – all with windows opening on this unexpected space, a fairylike situation unique in the city without trees… To keep this immense treasure untouchable in the very center of Manhattan, I think that that shows a high civic attitude, an extraordinary attitude.  It is the sign of a strong society.

Rockefeller Center

Consider the most recent skyscraper, Rockefeller Center.  It is rational, logically conceived, biologically normal, harmonious in its four functional elements: halls for the entrance and division of crowds, grouped shafts for vertical circulation (elevators), corridors (internal streets), regular offices.

Already the skyscraper is large enough to have made it possible to spend the money necessary to do a good job.  The sets of bronze and glass doors are constructed with a machine-like rigor.

Times Square

People from the interior of the country, who have come on some business pretext, cannot really go elsewhere, for Broadway is the street of welcome: the cataccts of light which they have seen in the movies and read about in the papers have drawn them for a long time.  The places of entertainment and the displays of goods for out-of-town visitors are there.  It is the complement of the plains and the cornfields… The dream materialized here in a burst f light, of milling crowds, of carouses well framed by the glitter of chrome metal, brings to life again the great adventure of the 8:47 Train…on the scale of Manhattan.