The John Hancock Tower experienced several failures throughout the years, the most well-known of which being the falling windows. Over an acre of the structure was formerly covered in plywood, which replaced the broken glass. The problem was discovered in the design of the windows themselves. They were not strong enough to support their own weight, so they had to be bolted to the wall behind them.
The tower is also known for its poor insulation, which caused heating and cooling costs to be high. In an attempt to reduce these expenses, the building was not fully occupied during the summer months. When it came time to heat or cool the building, operators would only supply temperature controls to those floors that needed service at that time.
Another issue with the tower is its location: right in the center of Chicago's business district. This made the building highly susceptible to noise pollution. Even today, many people are unaware that this tower even exists!
The last major failure occurred in 2002, when a fire broke out on the 54th floor of the building. Although no one was injured, it became clear that the fire protection systems on that level were outdated and insufficient to contain a fire of that size. As a result, the entire 16th floor collapsed into itself.
Since then, all occupants above the 47th floor have been required to take elevators down to the ground floor instead of using stairs.
Fortunately for the inhabitants of Pisa, the lengthy construction delays allowed the building to settle and the earth to compress. This strengthened the foundation over time and is the major reason the tower never collapsed. The tower has been crumbling for hundreds of years. In 1772, an earthquake damaged some of the buildings in the area. This prompted the Pisans to repair and strengthen other parts of the city wall with their money. The leaning tower was not part of this project.
In the 19th century, tourists began visiting Pisa, especially Americans who wanted to see a "Leaning Tower". Because no one was actually leaning anymore, some thought it wasn't a real tower. In response, the Pisans repaired the top half of the tower again so it would look like it had always been that way.
In the late 20th century, more earthquakes have occurred in central Italy. Scientists think this may have caused the ground under the tower to expand more than expected, which could be why the tower continues to lean today. However, engineers say this effect is not strong enough to cause the tower to collapse.
The original design of the Leaning Tower called for 90 identical bells to be hung from it. Only 6 of these are still present today because many were stolen or destroyed during wars.
A storm rained more than double that amount of rain on the night the roof collapsed. Because of the force of the falling roof, parts of the walls were blown out. A badly built London skyscraper reflected and intensified sunshine to the point of melting automobiles and frying eggs. The architects should not have allowed it to be built without a fire escape.
The Gherkin was designed by Peter Cook and David Anderson and constructed in 2003. It is 381 feet (117 m) high and has 730 apartments. It is located near Buckingham Palace in the City of Westminster. The Gherkin uses less energy than any other building of its size and is completely flat, which should make it easy to heat using gas or oil. But the building's green features are probably what made it so popular: it collects its own rainwater and uses solar panels to power its lights.
Unfortunately, the Gherkin's beauty was only skin-deep. Beneath the glittering facade, it was actually built with cheap materials that were later torn off during refurbishments. In 2004, engineers discovered that the structure was at risk of collapsing under its own weight. The whole thing was supposed to be temporary but still... Engineers said that if the load of the top floor was too great, it could cause the lower floors to collapse as well.
But despite all this, people continued to move into the apartment blocks.
A collapse or "falling over" would not breakdown in that manner. Given the weight distribution of the tower's structure and the prongs you described, even if the tower did tilt from the bottom, it would most likely shatter in half or numerous parts fairly early in the fall. The force of each glass floor or wall breaking away from the tower would then cause more damage farther up, but it would be limited by the number of floors or walls left standing.
However, this is all just speculation based on how a typical glass skyscraper would break down. No one knows for sure how the CN tower will fall because no one has ever seen it collapse before.
When complete, the CN tower was the tallest free-standing structure in the world at 1,815 feet (541 m). It has since been surpassed by two other buildings. One is the 2,716-foot (828 m) Shanghai World Financial Center, which opened in 2009, and the other is the 2,747-foot (853 m) Burj Khalifa in Dubai, which opened in 2010. The CN tower is still the third-highest building in Canada behind only the Chrysler and John Hancock buildings in Chicago.
The CN tower is located in Montreal, Quebec. It was built as a symbol of Canada's participation in the Olympic movement and as an attraction for tourists to Montreal.
The John Hancock Center, located at 175 East Delaware Place, was erected in 1969. The 100-story high-rise holds 700+ condominiums. It is Chicago's second highest residential skyscraper and the third tallest in the United States. The John Hancock Building is part of the Gold Coast neighborhood on the city's North Side.
The building's construction was led by architect Wallace Harrison Eisenmann with architectural design by Bertrand Goldberg. The general contractor was William Miller and Associates. The site preparation and excavation were done by McDonough Construction Company at a cost of $1.5 million. The concrete for the foundation was supplied by Carter Concrete Products, while the steel was supplied by INA Iron Works. The building's roof is made of terra cotta tiles manufactured by Crown Terracotta of Canada. The heating, ventilation, and air-conditioning system uses R-134 refrigerant gas.
The building has 493 residential units from studios to three-bedroom apartments. It also has a fitness center, laundry room, outdoor pool, sauna, and tennis court on its 28th floor roof deck. The building's annual tax bill is $750,000.
Construction on the John Hancock Building began in October 1968 and it was completed in April 1969. At the time it was built, it was the most expensive single structure ever sold in Illinois (approx. $15 million).