Building Big: Skyscrapers Lecture Notes

Flashcards covering key architectural, historical, and structural engineering concepts from Chapter 1 through Chapter 7 of the Building Big skyscrapers lecture.

What was the key outcome of the 1929 Manhattan skyscraper height contest between the Chrysler Building and the Bank of Manhattan?

The Bank of Manhattan added a 50-foot flagpole to reach 927 feet and beat Chrysler by two feet, but Walter Chrysler secretly pushed a hidden needle-thin spire through the top of his building in November 1929 to claim the title at 1,046 feet.

Why were over 70 stone towers built in the medieval Italian town of San Gimignano eight hundred years ago?

They served as a second line of defense against invading forces threatening the town's trade wealth and provided fortification during a 150-year internal feud between the Ardinglees and Salvucis families.

How did the load-bearing stone architecture of San Gimignano's medieval towers affect their living conditions?

The lower walls had to be almost six feet thick to support the building's weight, leaving very little floor space and resulting in dark, cramped rooms with very few windows.

What structural engineering innovation allowed French Gothic cathedrals like Reims to feature large glass windows?

Flying buttresses, which were external stone arms supported by heavy piers that pushed back against the outward pressure of the heavy arched stone ceilings.

What foot-powered machine was used by master mason Jean Dorbe at Reims Cathedral to lift heavy stone materials?

The squirrel, a large wheel pedaled by a worker's feet that generated enormous leverage to lift objects up to the 150-foot vaulted ceilings.

Why was construction on Reims Cathedral halted for two years after twenty years of building?

The townspeople staged a bloody revolt because they were fed up with shouldering the heavy financial burden of building the cathedral.

How did Gustave Eiffel construct his tower in Paris in just twenty-one months for the 1880s World's Fair?

He built it out of strong, light wrought iron, assembling 12,000 prefabricated metal pieces like a metal bridge turned on its end.

What invention did Elisha Graves Otis demonstrate in 1854 that made tall passenger buildings practical?

The safety hoister, a mechanical braking system that automatically activated to stop the elevator platform if the hoisting cable snapped.

How rapidly did Gustave Eiffel recover the construction costs of the Eiffel Tower?

Elevator ticket sales from two installed Otis elevators recouped almost the entire cost of the structure in just one year.

What historic event in 1871 catalyzed Chicago's rapid skyscraper boom?

The Great Chicago Fire, which burned 17,000 buildings to the ground and created an opportunity to rebuild a new high-density city.

How did engineer William LaBaron Jenney conceptualize metal skeletal frame construction for the Home Insurance Building?

He observed a slender wire birdcage successfully supporting the weight of a heavy, brick-like photo album that his wife set on top of it.

What is the primary function of exterior walls in a metal skeletal frame skyscraper?

They support no building weight and act merely as a skin to keep out the weather, allowing buildings to have unlimited windows.

Why did Chicago cap the height of new building construction at 130 feet in 1893?

Citizens worried that taller buildings were blocking sunlight and turning the city's streets into dark, lightless canyons.

How did construction firm Starrett Brothers and Eakin achieve a building rate of more than a story a day on the Empire State Building?

They prefabricated mass-produced components off-site, laid tracks on every floor for small rail cars, and placed cafeterias on five levels so workers stayed on site.

Why was the Empire State Building called the "Empty State Building" after its opening on May 1, 1931?

Because of the Great Depression economy, the building was less than 25% occupied, forcing managers to leave lights on in vacant offices.

What happened when a B-25 bomber crashed into the Empire State Building in July 1945?

The plane hit the 79th and 80th floors, killing 14 people, but the heavy steel and masonry building absorbed the impact and reopened for business by Monday morning.

Why did glass-and-metal "International Style" box skyscrapers become widespread in the 1950s post-war era?

They were inexpensive, simple, and could be replicated very cheaply and quickly compared to stone-panel structures.

What structural strategy was used in the World Trade Center and Sears Tower to keep lightweight skyscrapers from swaying excessively?

Moving most column and beam structural elements to the perimeter to create a hollow rigid tube frame.

How does the tuned mass damper on the 63rd floor of New York's Citicorp Center stabilize the building?

It uses a 400-ton concrete block floating on oil with springs and shock absorbers that glides side-to-side in opposition to the building's wind sway.

Why was Citicorp Center constructed nine stories in the air on four central support columns instead of corner columns?

To accommodate Saint Peter's Church, which was rebuilt directly under one corner of the building site as part of a real estate deal.

What critical structural defect did engineer Bill LeMessurier discover in Citicorp Center after its completion?

The diagonal V-brace joints were bolted instead of welded to save money, creating a risk that diagonal winds from a 16-year storm could break the joints and cause the building to collapse.

How was the Citicorp Center structural danger resolved in secret during 1978?

Welders worked at night for several weeks welding thick steel plates over the bolted joints before Hurricane Ella could strike.

What cultural motif inspired Cesar Pelli's floor design for the Petronas Twin Towers in Kuala Lumpur, Malaysia?

Traditional Islamic architecture, utilizing two overlapping skewed squares that form an eight-pointed star.

How is the 41st-floor double-deck skybridge on the Petronas Twin Towers designed to handle building movement?

It rests on two pairs of legs that allow it to glide about a foot in and out of the towers as they sway and twist in the wind.

Why did the World Trade Center towers ultimately experience a pancake collapse during the 2001 attack?

Intense jet fuel fires reached nearly $1000^\circ\text{F}$, weakening the structural steel until the concrete floor slabs collapsed under the weight above.

According to the PBS Kids Zoom segment, what are the three main structural forces that act on a skyscraper?

Compression (pushing materials together), tension (pulling materials apart), and torsion (twisting).