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By Kevin Griebenow, Class of 1993, Education Guide, DCE [1], RPCV

The new book by Stefan Al – who writes as an engineer as well as an architect – is succinct and to the point.  His technology section tells what you need to build a super-tall building, including concrete, wind resistance, elevators and air-conditioning.  And the book’s society section looks at how skyscrapers have impacted cities, and how cities have impacted skyscrapers.  Specifically, the cities of London, New York, Hong Kong and Singapore.  Unfortunately, Chicago didn’t make the cut.

But the author tries to redeem himself by stating, “Chicago had the first [skyscraper] with the completion of the 10-story Home Insurance Building in 1885” [2].  The book is full of quotes and stories. Al credits Louis Sullivan as the father of the skyscraper, as Sullivan wrote, “It must be tall, every inch of it tall.”  He points out that Sullivan highlighted the struggle we have, even today, to make tall buildings look graceful instead of a “staring exclamation of eternal strife.”  And he says that Frank Lloyd Wright’s proposed triangular footprint for his unbuilt mile-high Illinois Building foreshadowed a similar approached used for Dubai’s Burj Khalifa and the Jeddah Tower in Saudi Arabia — noting that the triangular form is “the surest form of resistance.”

As an engineer who deals with concrete and dams, I found the first chapter – “The Building Block that Binds the World: Concrete” — gripping.  It does an excellent job of reviewing the history of concrete, focusing on the great durability of ancient Roman-made concrete.  We use a lot of concrete, about 10 billion tons per year or appx. 20 bathtubs per person per year.  Author Al explains how the increase in the compressive strength of concrete at 8,000 tons per square meter [3] made possible the construction of the Burj Khalifa.

Concrete & Sway

Compressive strength and added chemicals — air entrainment, fly ash, superplasticizers and silica fume — alter concrete’s properties to make it pumpable, workable and durable.  And the construction of tall buildings would not be economical without a pump.  Al states that the construction of the Burj was “entirely dependent” on pumping concrete instead of its tedious delivery by buckets lifted by a crane.  For the Burj, the German company created the Putzmeister BSA 14000 SHP-D.  The pump can generate 31 MPa [4] and was able to pump concrete up 1,972 feet during the construction of the world’s tallest structure.  This fact shows that the methods of construction are as important, if not more, than the increasing strength of building materials.

Chapter two focuses on the sway (aka acceleration) that wind induces in buildings.  Al notes that a doubling of wind speed will quadruple the wind pressure on the building (i.e., wind pressure is proportional to the square of the wind speed).  However, the bigger problem with whirling wind and swaying has to do with its effects on a building’s inhabitants.  So, the investigation of the sensitivity to humans with this swaying motion is told in detail.

Fazlur Khan

The author references Chicago, the structural engineer Fazlur Khan working with Skidmore Owens and Merrill (SOM), the John Hancock Building and Khan’s contribution to the Museum of Science and Industry.  Khan modified the museum’s washing machine exhibit called “Tale of Tub” that measures peoples’ perception of a structure’s sway.  With this information, the engineer was able to convince skeptics at SOM that his structural design for the John Hancock was adequate.

Al relates a story about finding the upper limits of human tolerance by tests with “very questionable ethics” that were done preparatory to the construction of the original World Trade Center buildings.  Well-described also is the issue of “confusing the wind” to break up vortex shedding as winds break away from a building.  The classic example of what happens when shedding occurs at the same frequency as a structure is the dramatic collapse of the Tacoma Narrows Bridge [5] in Washington state.

Elevators & AC

The need for safe and fast elevators to move people in skyscrapers is addressed in the third chapter.  Early elevators were dangerous machines.  And the book’s statistics about the speed and numbers of elevators installed throughout the world would cover any docent’s note card.

Also, well-told is the history of air conditioning and its impacts on buildings.  The nugget in this chapter involved the standard for determining the ideal temperature for human occupation in the 1960s, which “was based on the metabolic rate of an average male wearing a suit.”  So, the temperature was considered “ideal” if you were in a suit and tie.  But if you weren’t suited, you should probably pull on a sweater.

The societal issues cited by the author focus on four cities: London, New York, Hong Kong and Singapore (again, no Chicago).  The chapter I enjoyed the most was the one about London.  The city originally restricted the height of skyscrapers to be no taller than Christopher Wren’s 365-ft. St. Paul’s Cathedral (1710).  The nicknames of the structure built after the lifting of the restriction in 1963 are fun: the Shard, The Gherkin (officially 30 St Mary Axe), Walkie-Talkie, Armadillo, Helter Skelter and Razor.

The author concludes with a discussion about the future of tall buildings and a more sustainable world.  Stefan Al notes that the taller a building, the more energy it consumes. But innovation will continue to make them stronger with less material, better able to withstand wind and sway, more comfortable for occupants, and more efficient in moving people. He insists that a new paradigm is needed beyond being taller: build them greener, reduce carbon emissions, generate energy, and ensure a healthier environment.  As highlighted by Paul Goldberger’s review of the book in the New York Times [6], we need to make skyscrapers more than “a machine that makes the land pay.” [7]

As an epilogue, having been a Peace Corps volunteer in Yemen, I cannot let it pass that Stefan Al also mentions the “Manhattan of the Desert,” Yemen’s ancient mud skyscraper city of Shibam.

 

[1] Dam Civil Engineer, Returned Peace Corps Volunteer.

[2] P. 58 the paragraph starts “Many define the first skyscraper by the use of steel-frame construction. Chicago…”

[3] 11,000 psi.  In the 1980s, typical concrete strength was 3,000 psi.

[4] 4,500 psi.  Being a dam engineer I find it helps to convert these pressures to a column of water.  This pressure is at the bottom of a water column 10,400 feet high!

[5] https://www.bing.com/videos/search?q=tacoma+narrows+bridge+collapse&view=detail&mid=1CAD27C9722319D772261CAD27C9722319D77226&FORM=VIRE

[6] NYT May 15, 2022, Paul Goldberger is a Pulitzer Prize-winning architecture critic.

[7] Cass Gilbert

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