11 of the biggest structural failures in history

The Tacoma Narrows Bridge twisted back and forth in strong winds before collapsing in 1940. The failure is now a case study for physics students.

Location: Tacoma, Washington

Cost: $11 million

Constructed: 1938-1940

Issue: Flexibility and unstable cables

Date of incident: 1940

Also known as "Galloping Gertie," the Tacoma Narrows Bridge in Washington collapsed only four months after opening for public use. The bridge spanned the nearly mile-wide Puget River, making it the third longest suspension bridge in the world, behind the Golden Gate Bridge and the George Washington Bridge.

But its length was not what made the bridge so famous that it continues to fascinate engineers and physics professors to this day. It was that under even moderate wind speeds, the bridge would undulate like a sine wave. Construction workers noticed problematic bucking even while building the bridge, leading to its famous nickname.

While the original designer intended to create greater stability with a more standard design, the cost was exorbitant, around $200 million in today's money. Instead, a cheaper option using plate girders gained approval. The girders, though, were only one-third the height of the originally proposed trusses, which resulted in a disproportionate depth-to-width ratio. As a result, the bridge was extremely flexible and vulnerable to high-speed winds.

When a 40 mph wind struck on November 7, 1940, the bridge started to twist and buck wildly. The bridge finally gave way, snapping the support cables and dropping into the river below.

A walkway at the Hyatt Regency in Kansas City collapsed in 1981, killing 114 people.

Location: Kansas City, Missouri

Cost: $50 million

Constructed: 1978-1980

Issue: Weight distribution

Date of incident: 1981

While most structural failures are noticed in time, the Hyatt Regency in Kansas City, Missouri, wasn't so fortunate. On July 17, 1981, 114 people were killed and an additional 200 people injured when the fourth-floor elevated walkway collapsed, falling onto another walkway two floors down, and eventually into the lounge below.

When the hotel opened in 1980, it boasted a sleek and elegant design, which included a multi-story atrium with three suspended walkways running through it. The walkways were anchored by 1.5-inch steel rods, but the real issue lay in the change from a single set of hanger rods threaded through the upper walkways to a double-rod system that was anchored to the upper walkways themselves, adding immense and undue stress. The design was incapable of meeting the minimum safety requirements, but had gone unnoticed in the building process.

The collapse occurred during a Friday night "tea dance" in the lobby. Local police chief Norman A. Caron said it was "the worst disaster" in his 25 years as a police officer.

All 10,344 window panes of the John Hancock Tower needed to be replaced because of poor glass integrity.

Location: Boston, Massachusetts

Cost: $175 million

Constructed: 1968-1976

Issue: Flexibility and poor glass integrity

Date of incident: 1973

As the tallest building in Boston, the John Hancock Tower (now simply known as 200 Clarendon Street) was mired in controversy even before it was built.

Initial plans showed that it would cast a shadow over Trinity Church, leading to public outcry and a quick redesign of the building. Despite this effort, the building continued to trouble the public.

During construction, the blue reflective glass used for the building started to fall off from various heights, forcing police to close off the area around the building. Subsequent research in wind tunnels identified additional integrity issues, such as twisting in high-power winds.

The real issue, though, was that the building expanded and contracted wildly due to differences in temperature inside and outside of the building. The reflective material caused the glass to be stiffer than expected, and instead of absorbing motion, it transferred it and simply shook out of place.

All 10,344 window panes were replaced by single-paned, heat-treated panels, helping inflate the cost of the project. During the time it took to identify and fix the problem, sheets of plywood replaced many of the missing panes, earning the nickname "Plywood Palace."

The roof of the Kemper Arena in Kansas City collapsed during a rainstorm because of drainage issues.

Location: Kansas City, Missouri

Cost: $23 million

Constructed: 1972-1974

Issue: Poor drainage

Date of incident: 1979

As the new home of the Kansas City Kings, the arena was hailed as an innovative design that featured a seamless design. The architect even won an Honor Award from the American Institute of Architects.

Only a few years later, the roof of the arena collapsed during a heavy rainstorm due to a case of prizing form over function.

Ironically, architects from the AIA visited the building during its 1979 convention, only a day before the roof finally gave way.

The roof was flat, which raised some concerns as to how it would handle weather. As such, the design included a temporary reservoir to reduce stormwater runoff, but it only had eight drains, despite local code requiring at least eight times as many. As a result, the reservoir could only contain 2 inches of rain before overflowing. On the night the roof collapsed, a storm dumped more than double that much rain. The collapse was so violent that pressure from the falling roof blew out some of the walls.

A poorly designed tower in London reflected and magnified sunlight until it was melting cars and frying eggs.

Location: London, England

Cost: More than $250 million

Constructed: 2009-2014

Issue: Heat amplification and wind tunnel

Date of incident: 2013

A common issue in design and construction results from the way light can reflect and even amplify off glass and metal.

The curved design of the Vdara Hotel in Las Vegas, designed by Rafael Viñoly, basically turned the building into a giant magnifying glass, intensifying light so much that it harmed hotel guests and earned it the nickname "Death Ray Hotel."

However, it is Viñoly's building in London, 20 Fenchurch Street, that really stands out, not only for its death ray effect, but an additional wind tunnel effect, turning the neo-futurist building into a total menace.

Constructed between 2009 and 2014, the building earned the nickname "Walkie Talkie Centre" due to its appearance. The concave shape of building meant that when sunlight shone directly on it, it acted as a mirror and focused the light onto the street below. Temperatures reached over 160 degrees Fahrenheit, famously melting a man's Jaguar, and getting so hot that journalists were able to fry an egg on the sidewalk.

The building eventually had to install screens at certain points to prevent the reflection of direct sunlight. Additionally, the building caused increased wind activity at the street level. The winds were so strong they were blamed for blowing over street signs, trolleys, and pedestrians.

The largest stadium disaster ever occurred in ancient Rome and resulted in the deaths of over 20,000 people.

Location: Fidenae, near modern-day Rome

Cost: N/A

Constructed: around 27 AD

Issue: Rushed construction, untested integrity

Date of incident: 27 AD

Ancient Rome was famous for its bloody gladiator fights — but one of the most horrific disasters in history had nothing to do with the combatants on the ground.

One notable venue for gladiator games was an amphitheater erected in Fidenae at the bidding of an entrepreneur named Atilius. Despite his wealth, he aimed for a quick construction over a sturdy one — according to some sources, he urged the builders to use cheap materials (mainly wood) to build the stadium, and it was erected on unstable foundations.

Most of the information about the disaster comes from ancient texts, such as ones by Tacitus and by Tiberius, but they tell a singular story: When 50,000 people flocked to Atilius' stadium to watch a gladiator fight, 20,000 of the audience members fell to their death as the seating collapsed. Many of the remaining patrons were severely injured.

Following the incident, the senate banned anyone from building a stadium unless their wealth exceeded 400,000 sesterces, and the stadium had to pass a safety inspection.

A wedding in Israel ended in tragedy when the venue's floor collapsed, killing 23 people and injuring 380.

Location: Jerusalem, Israel

Cost: N/A

Constructed: N/A

Issue: Inferior materials, design alterations

Date of incident: May 24, 2001

In what is Israel's deadliest civilian disaster, the floor of the Versailles wedding hall in Jerusalem collapsed during the wedding of Keren and Asaf Dror in 2001, dropping 23 attendees to their deaths and injuring hundreds more. The event was captured on camera and broadcast internationally, spreading images of the horrific scene around the globe.

Initially, people suspected terrorism, as noted by police at the scene, but an investigation quickly dispelled that concern. Witnesses described the floor sagging before the collapse. According to Haaretz News, the main issue was the Pal-Kal building method, a cheap method of constructing light-weight concrete that was banned shortly after the incident.

Additionally, the building was originally designed in two halves, with one side only two stories and the other side three stories. Half of the third floor, then was only meant to be a roof and lacked structural strength. Partitions in the lower floors helped handle the difference in load-bearing, but the owners decided to remove the partitions shortly before the wedding. The floor sagged immediately, although the owners deemed it a cosmetic issue rather than a structural one.

Following the disaster, the creator of the Pal-Kal method, Eli Ron, was arrested and convicted of 23 negligent deaths as well as negligent assault on the remaining victims.

The tallest cathedral in the world is technically still unfinished because its height created structural issues.

Location: Beauvais, France

Cost: N/A

Constructed: 1225-1272 (technically unfinished)

Issue: Wind resonance and poor reinforcement

Date of incident: 1284

The Beauvais Cathedral claims to be the tallest cathedral in the world, but that fame came at a strange price. To achieve the height, the builders and planners had to push their resources to the limit, and the building suffered as a result — in fact, the cathedral is technically unfinished, even if it is functional.

The current cathedral is merely part of the original plan. Started in 1225, the foundations indicate that the cathedral was meant to be truly immense, but the only part that was finished for use was the choir vault and the central nave. The main body of work was finished in 1272, and services started immediately. In 1284, part of the choir vault collapsed due to the strain and, possibly, vibrations from high speed winds. Additionally, some of the other parts of the cathedral that were not completed might have added necessary support and reinforcement.

Repairs were made, as were additional attempts to build other parts of the cathedral, but the height proved too troublesome. Work finally ceased in the 1600s, but additional reinforcements have been added as needed over the centuries to the current structure.

The Banqiao Dam failed to handle a 'once-in-2,000-years flood,' but additional construction could have spared thousands of lives.

Location: Zhumadian City, China

Cost: N/A

Constructed: 1951-1952, further work in 1954

Issue: Record flooding, lack of overflow options

Date of incident: August, 1975

The deadliest structural failure in history occurred in China when the supposedly unbreakable "Iron Dam" in Zhumadian city burst in 1975.

Built in the early 1950s, the dam was built under supervision by Soviet engineers. A flood in 1954 forced the government to extend their existing dams, including a 3-meter addition to the Banqiao Dam walls.

When cracks started to appear in the dam, they were repaired with advice from the Soviets again, and additional reinforcements were added. The engineers claimed that the dam could withstand a "once-in-1,000-years flood."

The chief designer of the dam, Chen Xing, was vocal that the design was flawed, though. He recommended 12 gates to handle the overflow, but he was ignored, and only five gates were built. Other dams in the same system had similar reductions.

As a result, in 1975, record rainfall of nearly 7.5 inches of rain per hour (almost 42 inches a day) strained the dam to its limit. Requests to open the dam and relieve pressure were rejected due to flooding elsewhere. After another two days of rain, the dam broke.

Thousands died in the initial flooding. The government intentionally destroyed several other dams with air strikes to divert the water and reduce damage, but it was too late: Thousands more died, and those who survived suffered from famine and disease without food or shelter. A total of more than 200,000 people died as a result of the catastrophe.

A tank exploded in Boston, flooding a neighborhood with molasses and killing two dozen people.

Location: Boston, Massachusetts

Cost: N/A

Constructed: 1915

Issue: Temperature variance, untested integrity

Date of incident: January 15, 1919

In the North End neighborhood of Boston, the Purity Distilling Company stored molasses for transfer to a facility dedicated to fermenting molasses to produce ethanol. On January 15, 1919, a tank containing 2.3 million gallons of molasses burst and flooded the neighborhood.

The molasses had been warmed to reduce viscosity during transfer, but the warmer material, in addition to the rapidly warming air temperature, must have strained the tank itself. Around noon that day, the tank burst open.

The millions of gallons rushed out of the tank at 35 mph, reaching heights of 25 feet at their peak. The molasses was dense enough to push over buildings. When the molasses settled, it was waist-deep and dragged people down. Twenty-one people died, and around 150 were injured by the wave.

Residents brought a lawsuit against the US Industrial Alcohol Company, which owned Purity Distilling at the time. The company claimed the tank was blown up by anarchist because ethanol is an active ingredient in munitions, but an auditor nevertheless found the company responsible.

According to engineer Ronald Mayville, the tank was constructed poorly, with thin metal that proved brittle under certain circumstances. Additionally, the tank itself was never properly tested. According to The Guardian, the company ended up paying $628,000 in damages — the equivalent of over $9 million today.

And lastly, perhaps the most famous structural mishap: The Tower of Pisa famously leans because of an architectural blunder.

Location: Pisa, Italy

Cost: N/A

Constructed: 1173-1372

Issue: Poor foundation

Date of issue: 1378

The most famous of structural failures has to be the Leaning Tower of Pisa. Situated behind the Pisa Cathedral, and known simply as the Tower of Pisa, the tower was originally built to house the bell of the Pisa Cathedral complex.

The tower was built on an entirely unstable foundation. An altogether too-small limestone base of only 3 meters deep was built into a dense clay bed, which meant the tower was never going to last. Only three levels of the planned eight were completed by the time a war broke out between city-states, which gave the foundation time to settle, possibly preventing a collapse while the building continued.

Only five years after completion, the tower started to achieve its now famous lean, slanting at nearly 10 degrees. Only in the '90s did the authorities deem action necessary, adding 600 tons of counterweights to the base. Of course, the Tower's lean has made it a beloved tourist attraction, so maybe it wasn't such a failure after all.