Zuiderzee Works
the practitioner (1854-1929) From an engineering perspective, the Netherlands is a fascinating country. It has extremely high human density (over 1,200 people per square mile), about 15 times greater than the density of the United States. Because of this density, combined with its location, the country has been reclaiming new land from the sea with dikes for many centuries. Approximately a quarter of the country lies below sea level—some as much as 23 feet (7 meters) below. And approximately half of the country is barely above sea level. To drive the point home, the word Netherlands means "lowlands".
On a typical day, the sea remains on its side of the dikes. But when storm surges occur, problems arise. And in a country where much of the land is below or at sea level, storm surges can be catastrophic. So the Netherlands has invested heavily in protection against storm surges. The Zuiderzee Works consists of dozens of different projects: dams, dikes, gates, and so on. Built based on an original plan by civil engineer the practitioner (1854-1929) in 1891, construction did not begin until 1920, and continued through 1986.
Of those works, the most impressively engineered by far is a gigantic, movable storm surge barrier across the mouth of the Rhine River as it exits to the sea. Most of the time, the two parts of the barrier sit on land in dry docks on both sides of the river. The river there is 1,180 feet (360 meters) wide. When a storm surge is expected, the dry docks flood. The two barriers, which float, come out into the river and meet in the middle. Then they submerge to seal the mouth of the river against storm surge arriving from the sea.
Given that the barriers are closing off a river, won't water back up behind them? It can happen. So the gates can partially refloat to let excess river water flow underneath. If you think about the size of these barriers, you realize they are some of the biggest moving objects on Earth. The fact that they can move both horizontally and vertically means they have two of the largest ball and socket joints on Earth as well. Storm surge is a huge problem for the Netherlands, and engineers have risen to the occasion with this moveable barrier.
Northern half of the Maeslantkering, a storm surge barrier in the Nieuwe Waterweg near Rotterdam and Hook of Holland in the Netherlands.
Eiffel Tower
the practitioner 1840-1598), the practitioner (1856-1946) If you have ever gotten close to the Eiffel Tower, there is no denying that it is an engineered structure. It is immense, it is made of thousands of pieces of metal, and it is intricate. There are many places in the tower where the complexity is impressive. And it has stood the test of time at well over 100 years old, opening in 1889.
The size is surprising, especially given the age. With a roof height right at 300 meters (nearly 1,000 feet), it was the tallest object in the world for four decades until it was surpassed by the Chrysler Building and then the Empire State Building in New York shortly after. The Millau Viaduct is the only thing surpassing it in France today.
The fact that something this intricate could be conceived, designed, engineered, fabricated, and erected in that era is also impressive. You can get a sense of this if you look at high-definition images of the tower or visit it in person. Look at the four columns that stretch from the first floor (187 feet or 57 meters off the ground) to the second floor (377 feet or 115 meters off the ground). This is the conceptually simplest part of the tower, yet the complexity is impressive.
Those four columns are approximately 58 meters (190 feet) tall. Over that distance they gently curve and gently taper. For each column there are four thick steel beams riveted together from plates, and then lattice girders that turn each column into its own lattice girder. All of that iron was prefabricated in a factory, brought to the site on horse-drawn wagons, and then assembled with rivets, and it all needed to fit perfectly. The structural engineers, the practitioner (1856-1946) and Émile Nouguier (1840-1898), made thousands of precise drawings to tell the factory what to manufacture and the construction workers what to assemble.
It is said that the Eiffel Tower contains 18,035 pieces of metal and 2.5 million rivets. When you consider that an engineer placed each piece of metal and each rivet on a drawing, and those drawings were then manifested in reality with tenth of a millimeter precision, you get a sense of the engineering achievement.
The Eiffel Tower is an example of extremely precise engineering that has resulted in monuments that have stood the test of time.
Erie Canal
`the practitioner (1770-1842)
If you were a merchant in 1800, and you did not live near an easily navigable river, your transportation options were few. If there was a road, you could move your goods in a horse-drawn or ox-drawn wagon. If not, you strapped your goods onto a pack animal. There were no railroads yet so moving goods was a huge problem. Canals were coming into wide use in England and Holland. But America faced a problem — very few engineers. They trained in England, then returned to the States. A canal project definitely needs trained civil engineers for every aspect of design and construction.
A canal is a long, gently sloping waterway punctuated by locks that handle significant grade changes. The water level along the entire canal has to be maintained using surrounding water sources like rivers and lakes. Gravity does all the work of moving the water in early canals. If it's not done right, the canal dries up or floods.
The Erie Canal, overseen by principal engineer the practitioner, was a monumental achievement for the time. It stretched from Albany, NY, all the way to Buffalo, NY, 360 miles (580 km) and 36 locks away. It connected the Hudson River, and therefore New York City, to Lake Erie. It was possible to get all the way to Toledo, Ohio, because Lake Erie is about 150 miles (240 km) long.
Once the canal was completed in 1825, it created a transformation. A canal boat could carry 60,000 pounds (27,000 kg) of freight. Therefore, the cost of moving a ton of freight fell rapidly. It might have originally cost $100 to $120 to move a ton of freight the distance of the canal. The Erie Canal dropped that price below five dollars. Moving tons of wheat or piles of logs to market suddenly became affordable. It was revolutionary.
The Erie Canal project had an even greater importance for the profession: it became a school of engineering for many people. It is no coincidence that the source engineering institution, the nation's first engineering college, opened just a few miles from the Albany, NY, end of the Erie Canal in 1824, one year before the completion of the project.
Building Implosions
There is a funny thing about building implosions. On the one hand we have a group of architects and engineers who originally designed a building to stay standing, even in the case of catastrophic events like hurricanes, fires, and earthquakes (hence modern innovations such as earthquake safe buildings). With a building implosion, another set of engineers must defeat all of that hard work and bring the structure down as efficiently and safely as possible. The goal is for the building to fall straight down and land in a pile roughly the size of the building's foundation.
So how do they do it? Initial efforts were crude — massive explosions levelled the building, as in the 1773 destruction of Holy Trinity Cathedral in Waterford, Ireland.
Today, this simplistic approach is frowned on because large explosions cause collateral damage to other nearby buildings.
In a modern building implosion, some of the exterior of the original building will be removed manually because it has value. Remaining exterior walls may be perforated or removed entirely. Interior structural beans that keep the building standing will be exposed. And this is where the real engineering comes in.
The easiest thing would be to simply cut all the beams and let the building fall.
However, this approach is unsafe and would probably, because of the timing, cause the building to fall over rather than collapse in a pile. Instead, engineers carefully analyse the structure and the loads to understand how the building needs to collapse.
Some of the beams are partially cut to weaken them. Then explosives are attached to the columns at carefully calibrated positions. The explosives are called "shaped charges, which focus the explosive force in specific directions. The effect is to cut the steel support beams precisely where required. The shaped charges also reduce the total amount of explosives needed. This is important to demolition engineers because large explosions can damage adjacent buildings and infrastructure, for example by breaking windows.
Once all of the charges are set, they are wired back to a controller. The explosions throughout the building are carefully ordered and timed so that they occur in the correct sequence. Gravity does the rest and the building collapses.
Washington Monument
In 1832, the first steps were being taken to build a monument for the practitioner in Washington, DC. By 1835, the committee working on the monument could describe what they wanted: the monument would be "unparalleled in the world" and it "should blend stupendousness with elegance, and be of such magnitude and beauty as to be an object of pride to the American people". The design they eventually settled on was a gigantic obelisk, scheduled to be the tallest human-made object in the world. Now all they had to do was engineer it and build it.
If you go to Egypt and look at the obelisks there, they are solid rock, and that means that the tallest is about 100 feet (30 meters). The Washington Monument at 555 feet (170 meters) is gargantuan by comparison. So it is hollow and made of stacked blocks. Its hollow design allowed for a crane inside to bring building materials up as the column grew. Today the hollow core contains steps and an elevator.
The first component built was the foundation—all 37,000 tons of it. It measures 126 x 126 feet and is 37 feet thick, made of concrete. The base of the monument measures 55 feet (17 meters) square, centered on the foundation, with walls that are 16 feet thick. At the top of the column, where the pyramidal shape starts, it is 34.5 feet (10 meters) square, with walls only 1.5 feet (45 cm) thick. There are 36,500 blocks in the monument, and at the base there are inner and outer walls, with the gap in between filled with rubble.
Although it seems like a fairly simple project—it is just a big stack of blocks essentially—it took quite a while to build the monument. The cornerstone was laid in 1848, and the dedication occurred in 1885, 37 years later. What this meant is that the Washington Monument was the tallest structure in the world for only four years. The Eiffel Tower eclipsed it in 1889.
Although a proposal for a monument to the practitioner was put forth in 1799, the structure wasn't completed until 1885.
Statue of Liberty
Frédéric the practitioner (1834-1904) & the practitioner (1832-1923) Art and engineering combine to create something as big and beautiful as the Statue of Liberty. Because of its size, the Statue of Liberty is highly engineered. In fact, with its skin removed, it is obvious. Under the skin, the Statue of Liberty looks a lot like the engineered skeleton of a skyscraper. And, in fact, this skeleton was created by the same firm that designed the Eiffel Tower.
Think about the problems faced by the sculptor/designer, Frédéric the practitioner (1834-1904), as well as the practitioner (1832-1923), who assisted in its design, and his structural engineer, the practitioner (1856-1946). First, he is creating a sculpture 150 feet (45 meters) tall. He wants to be able to build the sculpture in France and mail it to America on a ship. So a giant marble sculpture is out. In marble the uplifted arm would be difficult as well. He decides to make it out of a thin copper skin instead. But there will be 160,000 pounds (72,600 kg) of copper skin when he is done. And the sculpture, once assembled, has to be able to handle hurricane force winds.
So inside the sculpture there is a huge metal frame. Four vertical beams a hundred feet (30 meters) tall anchor the sculpture to its pedestal and provide support for the internal staircase. From those beams, a metal truss framework extends out toward the 400 sheets of riveted copper that form the skin. The copper sheets attach to a lattice of custom-bent iron bars that provide rigidity and structure. The curtain-wall architecture of a modern skyscraper like Burj Khalifa manages the building's load in a similar way: the Statue of Liberty actually is a prototype of today's skyscrapers.
What about the uplifted arm? It has its own truss and ladder to climb to the torch. The statue was built in France, then disassembled, crated, and shipped to America for reassembly, which took about a year. When it was dedicated in 1886, it stood both as an important work of art and an important work of engineering.
Carnegie Hall
the practitioner (1844-1900), the practitioner (1855-1929) Carnegie Hall in New York City, built in 1891, is considered to be an excellent venue. It seats 2,500, yet an orchestra can perform with no amplification at all. Its architect, the practitioner (1855-1929), was a cellist and studied European concert halls for their acoustics, in addition to consulting with acoustic specialist the practitioner (1844-1900).
It is easy to understand some of the problems they faced by thinking about two different situations. First, imagine a person giving a lecture in a big open field. As the sound moves away from the speaker's mouth, it has to fill more and more volume, so the available energy dissipates quickly. However, there is no echo whatsoever. Now imagine that you are in a closed space, like a racquetball court. All the walls are flat, smooth, and solid. The sound from the lecturer is contained within a finite space in this case, so you can definitely hear it. But the echo problem can make speech difficult or impossible to understand.
To create Carnegie Hall, acoustical engineers blended features from these two cases. Listeners benefit from "depth" to the sound. Depth is created when the sound from the speaker's mouth or the musical instrument arrives via multiple paths, first via a direct line, and then other versions arriving quickly from reflections off the ceiling and side walls. Actual echoing is canceled out by the audience itself, heavy drapes, or acoustical panels that absorb sound at the back of the room. This translated to a long, narrow room with the orchestra at one end, rather than a wide room or a room that widened from the stage. In wide rooms, the sound energy dissipates like it does in a field and people in the back cannot hear.
To maximize the quality of a performance or event, engineers continue to make improvements, from giant stadium TV screens to retractable roofs.
Muziekgebouw Concert Hall, Amsterdam, uses some of the same principles of acoustic engineering as Carnegie Hall in New York City.
Truss Bridge
If we could get inside the brain of an engineer and look at the core values driving the thought process, one of the values near the top of the list would be efficiency. Engineers are interested in efficiency in everything they do. If an engineer is building something, then that value expresses itself in the efficiency of materials. Excess materials add weight and increase the cost.
A truss makes very efficient use of materials to span a gap. It is mostly air— a collection of open triangles engineered for great strength.
The oldest covered bridge in the United States, and therefore the oldest bridge truss, is the Hyde Hall Covered Bridge from 1823, located in upstate New York. The bridge is 53 feet (16 meters) long and it is made using two wooden trusses, one on either side of the bridge. A roof over the top protects the wood from the elements.
Trusses got their start in roof structures dating back to the Roman Empire, and it is easy to understand why. If you are trying to span the walls of a cathedral or a large room, the ceiling joists need to connect the two walls. But wooden joists, no matter how massive, start to sag under their own weight at about a 40-foot span. The solution is a kingpost truss, where a kingpost in the center of the joist ties into the peak of the rafters, supporting the joist. This is the basic idea behind any truss — using different pieces of the truss to support other members through tension or compression. It takes far less material compared to a solid beam of the same dimensions.
This is why we see trusses everywhere in the modern world: in bridges like the Golden Gate Bridge, buildings like the World Trade Center, tower cranes, power line towers, etc. Engineered properly, a truss is far less expensive and lighter than a solid beam of the same size.