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  • This episode of Real Engineering is brought to you by Brilliant. A problem solving website

  • that teaches you to think like an Engineer.

  • Barcelona is a city characterized by regimental city blocks and wide linear streets.

  • A departure from the narrow winding streets of most European cities. Yet nestled in these

  • rigid streets are some of the most unique and beautiful buildings ever created, each

  • rooted in nature through structural forms and designs.

  • These beautiful structures stand out among their neighbours, and are the work of one

  • the world's greatest architects. Antoni Gaudí. His buildings were not just inspired

  • by nature, they were a celebration of nature. A celebration of life and a celebration of

  • the God Gaudí devoted his life to.

  • The Casa Milà, Casa Batlló and perhaps most famously the yet to be finished Sagrada Familia.

  • All are within a short walk of each other and each is defined by their complex curves

  • that defied all conventional architectural rules.

  • These buildings were born from the mind of Antoni Gaudí, born in 1852 to a family of

  • craftsmen. Antoni Gaudí found much of his inspiration and meaning in architecture by

  • following the patterns of nature, using the beauty that he saw as a gift of god as the

  • ultimate blueprint to the world. Guadí himself once saidoriginality consists of going

  • back to the origins”, and that he did.

  • These complex intertwining parabolic forms, created in a time before computers existed.

  • Are so complex that his magnum opus, the Sagrada Familia, a building which began over 135 years

  • ago, is still under construction. Today we are going to learn it's story, and why it

  • has taken generations to complete.

  • Sagrada Familia began construction in 1882, under the guidance of architect Francisco

  • De Paula del Villar, who resigned a year later allowing Gaudí to take over at the age of

  • 30. Even at this young age Gaudí saw his opportunity, and set out to make the project

  • his masterpiece. Transforming the project and incorporating his signature style. Combining

  • Gothic and Art Nouvelle architecture to create something new.

  • Sagrada Familia looks like the work of evolution, rather than design. Like a giant elaborate

  • termite mound, whos blueprint was carved by the laws of nature. Gaudí was not just a

  • master architect, designing buildings in creative and innovative ways is the challenge of an

  • artist. He was a master engineer. He understood how these shapes impacted the structural integrity

  • of the building, and allowed physics and nature to dictate his designs. Rather than fight

  • against the laws of nature. He worked with them. He bridged art and science like no man

  • before him, he understood that nature is defined by the laws of mathematics, and to him this

  • was the ultimate celebration of god.

  • Columns mimicking trees and skeletons.

  • Arches mirroring rib cages.

  • Seashell inspired spiral stairways.

  • Spires emulating crystals

  • and ceilings that rival forest canopies for natural beauty. Their designs are all rooted

  • in natural phenomenon, but for a human mind to recreate them in stone took a man with

  • true genius.

  • So how on earth did Antoni Gaudí design something so complex in an era when computational analysis

  • did not exist. Evolution has happened upon these complicated structures through trial

  • and error. Natural arches are the work of chance, the weak simply fall before we can

  • witness them. While plants developed cells capable of sensing the direction of gravity

  • to influence their growth patterns and bone cells are stimulated to grow and multiple

  • when placed under stress. Nature is the ultimate form of intelligent design and Gaudi pursued

  • a simple concept to guide his replication of these designs.

  • The challenge that Gaudí faced was one of material strengths. His primary building material

  • being Montjuïc stone, a type of Sandstone. And like all stone it is strongest in compression.

  • Place a rock in compression and it can withstand enormous pressure, but place it in tension

  • and tiny imperfections in the rock allow cracks to grow, and soon the entire stone will fracture

  • along those cracks. The challenge with constructing structures using stone is primarily one of

  • keeping the stone in compression at all times.

  • This has been a well known building technique for thousands of years, but it was the Romans

  • who truly saw and utilised it's potential.

  • Unlike ancient greek structures characterised by vertical posts and horizontal lintel constructions,

  • roman buildings are defined by arches and domes. They raised massive structures, like

  • their famous aqueducts and the Pantheon dome. Structures that still stand today, a testament

  • to their sturdiness. The arches strength is derived from how it transfers weight to the

  • ground.

  • Let's compare a post and lintel structure and an arch spanning an equal distance. As

  • long as the posts remain vertical, they will remain entirely in compression. The downwards

  • force of gravity squeezing the stones against the unmoving ground. However, the horizontal

  • beam, the lintel, will experience both compression and tension as it sags from its own weight.

  • The upper surface will bend inwards, causing compression, while the lower surface will

  • experience tension as it is stretched. This severely limits its structural strength. An

  • arch in comparison allows the force to be distributed neatly across the arch. There

  • are no hard corners to allow bending stresses to develop. The reaction force from the ground

  • can travel smoothly up the same path as the force of gravity takes downwards, allowing

  • the stones to remain in compression, and thus allowing the arch to carry more weight.[1]

  • This imaginary path is called the line of thrust, and modelling it was Guadí speciality.

  • Designing with these concepts in mind is relatively simple for a 2D structure like an aqueduct,

  • but expanding it out to form something as complex as the Sagrada Familia is a whole

  • other ball game. Even thesimplecolumns of the basicalla's interior, split and diverge

  • like growing trees. The flying buttresses of the passion facade sweep outwards, and

  • defy belief that they could possibly remain standing when they are constructed from nothing

  • more than sandstone.

  • So, how did Gaudí do it?

  • Simple, he used strings. When you hang a flexible material like a rope over a gap, it has no

  • rigidity to allow it to remain in any position other than the one that allows it to remain

  • in pure tension. Hang a rope from a single point and it will hang directly downwards,

  • the entire length of string in tension. Hang it between two points and it will sag downwards,

  • until once again the entire string is in tension. Add more weight and it will sag with a deeper

  • parabolic arch to allow it to remain in tension.

  • You can see a pattern developing here. We can use strings to map out those lines of

  • thrust. But we want our stones to be in compression, not tension, how can we apply this to stones.

  • Simple, take a photo, and turn it upside down.

  • Gaudi started by drawing footprint of the church on a piece of wood at a 1:10 scale.

  • Next he attached anchor points for the strings in locations where he wanted support columns

  • to exist, from there he just gradually started adding strings and weights. The weights were

  • scaled to represent the actual weight the columns would need to support, at about one

  • ten-thousandth of the actual weight.

  • This weight was scaled to represent the difference in stiffness between the string and the rock

  • that it represented. He tinkered with the string model for a decade before he was content

  • with its final form. He used this model to inform his design work. In this reconstructed

  • model underneath the Sagrada Familia, you can see the shape of the building beginning

  • emerge. This was the skeleton upon which he would carve his masterpiece.

  • Gaudi devoted the rest of his life carving this model. Designing the intricate facades

  • each depicting stories from the bible, adding detail that few would see, and as the project

  • ran on, Gaudí withdrew from life, rejecting any additional projects. In 1914, he made

  • his home inside the Sagrada Família workshop. His obsession with his final masterpiece took

  • over his life. He neglected his personal appearance, and became a disheveled recluse. His days

  • were devoted to praying and overseeing the design and construction of the Sagrada Família.

  • And on June 7th, 1926. Disaster struck.

  • At the age 73 in 1926, Guadí was struck by a tram on his daily walk to confession, and

  • was left to die in the streets. Passersby did not recognise the ragged man as the famous

  • and beloved architect, mistaking him for a homeless man, he was left to die in the streets.

  • Hours later Gaudí was taken to the hospital, but received only basic care. When he was

  • finally recognised it was two late, no more could be done to save his life, and he died

  • two days later on June 10th, 1926. The funeral that followed, shut down Barcelona streets.

  • The residents of Barcelona showed up on mass, marching his coffin to its final resting place

  • in the crypt of the Sagrada Família. The project was less than a quarter complete at

  • the time of his death.

  • With the mastermind behind the complex project gone, completing it would become a herculean

  • task. Made even more difficult by the outbreak of the Spanish Civil War in 1936.

  • An already difficult task just became the world's most difficult puzzle, as anarchists

  • destroyed the only existing models of Gaudí designs. Here, the building could have been

  • abandoned, or it's vision changed. As Spain shook off the cobwebs of post war poverty

  • in the 1950s, a new generation of engineers and craftsmen devoted their skills to completing

  • his Gaudi's vision, employing tools and materials that Gaudí never had access to.

  • Attempts to piece together the shattered models back together were difficult, as pieces were

  • either too damaged or missing completely. But the designers that took up Gaudi's vision

  • worked with what they had. This is now their story. This is where this story really begins

  • to captivate me. This building has taken so long to complete, that it has spanned not

  • just generations of engineers, but generations of technology.

  • The passage of time has led to some increases in production rates, but has also caused it's

  • fair share of delays. Sandstone comes in a wide variety of colours, due to differences

  • in impurities. These can range from blues and greys right through to pink and red. [3]

  • When construction began on the Sagrada familia, this sandstone was in plentiful supply from

  • the Montjuic quarry. Its this stone that gives the Sagrada Familia its distinctive tan colour,

  • while also having a high quartz content making it more durable than most sedimentary rocks.

  • But as the decades passed, the stone began to become more scarce. In 1954, when work

  • began on the passion facade, the limited stock of the stone quickly became apparent. Soon

  • the sculptor's hands became idle, as the stones availability was limited to whatever was left

  • over in stocks or what could be scavenged from other buildings in Catalonia. [4]

  • 1000 metres cubed of the stone was made available when the old Olympic Stadium was remodelled

  • to increase spectator capacity. When stone was not available, they resorted to bricks,

  • which can be seen in many of the cathedrals towers. But recycled stone was always preferred

  • when possible. As the project drew on, these sources also began to run dry. Creating a

  • bottleneck in their supply chain that prevented work from continuing. The project's managers

  • were forced to start looking for alternative supplies from around the world. Over the past

  • few decades of construction the cathedral has incorporated various variants of sandstone

  • and granite. Doing their best to match their colour and physical properties to the original

  • Montjuic stone. Stone from Galicia, Cantabria, Scotland, England, France have all contributed

  • to help finish the Sagrada Familia, while other stones have been sourced to meet more

  • specific aesthetic requirements.

  • The passage of time has come with plenty of setbacks, but in recent years technology has

  • provided many blessings. Obvious improvements like modern cranes are noticeable, yet probably

  • unappreciated by the general public. 3D modelling softwares have slowly caught up with Gaudí's

  • genius. Early civil engineering software was too simple to recreate his designs, but architects

  • working on the project discovered that aeronautical engineering design software could model the

  • complex curves Gaudí envisioned and the project actually resulted in a merging of these softwares

  • to improve civil engineering modelling techniques. Cash flow has increased drastically over the

  • years too. For decades the only money the Sagrada Familia received was through donations

  • to the church, in the early days of construction these donations came in dribs and drabs, but

  • today the church has no shortage of funding, being one of the most popular tourist sites

  • in the world. Since it opened its doors to the public, Sagrada Familia has been raising

  • a consistent and reliable cash flow from the millions of tourists that pay to visit it

  • every year. Paying for the materials and workers needed to complete it.

  • But those workers are not always easy to come by. The art of sculpting has slowly withered

  • away over the past century, and skilled craftsmen are difficult to come by. Here technology

  • has come in to lend a helping hand.

  • Sculptures still play an important role in the process, completing delicate tasks like

  • surface texturing, but today most of the heavy duty cutting is now done by CNC machines,

  • which can cut the stone exactly to requirements and ensuring perfect fits between pieces and

  • for the internal steel supports. Because today the workers are not assembling the towers

  • stone by stone like in Gaudí's time. They are using tensioned steel bars running through

  • the centre of the stones to compress the stones together and form on larger panel. Allowing

  • pieces to be partially assembled before being lifted to the tower and assembled like a giant

  • stone lego set. This has drastically decreased construction time. [5]

  • With all of these advances the project is now expected to finish far sooner than originally

  • expected by 2026. On the 100th anniversary of Gaudi's death.

  • The building has undoubtedly diverged from Gaudi's original designs. The sculptures

  • of the passion facade are nothing like the sculptures of nativity facade built during

  • Gaudi's lifetime. Colours of the stone are off in places. The difference in weathering

  • between the nativity facade and the newer parts is particularly noticeable. The architects

  • that took up the mantle of Gaudí masterpiece could never have finished it exactly to his

  • vision after his plans were destroyed, but I have no doubt in my mind that Gaudí would

  • be proud to see his creation finally coming to a close. Entering the basilica you are

  • met with floods of colour from the stained glass windows. Each depicting stories of the

  • Bible, while filling the interior with colours reminiscent of rainbows, sunsets and light

  • piercing through a green forest canopy. I am by no means a religious man, but there

  • is something inherently spiritual about this building that I think any person who shares

  • that same awe of our mysterious existence on this planet will feel. For me, that is

  • the root of all religions and to me this building is the ultimate celebration of spirituality

  • through it's celebration of nature.

  • In the end I believe I express a great deal of my awe with this world through learning

  • how it works. I don't believe in the idea that learning science ruins our innate wonder

  • and awe in the mysteries of the world. It's the exact opposite. The more I learn about

  • how the universe works, the more amazed I am that we somehow exist to witness it all.

  • So satisfy that feeling of wonder and dive into the world of science and there is no

  • better place to start than Brilliant with plenty of courses in things from Geometry

  • and Maths so you can learn more about the complex parabolic curves that Gaudi used or

  • you could take the Classical Mechanics course which will run you through the science of

  • statics, essential knowledge for any civil engineer.

  • Brilliant are continually releasing new courses too like their new course on Search Engine

  • where you'll explore the core ideas behind the algorithms and data structures that make

  • search engines work.

  • All of Brilliant's courses have storytelling, code-writing, interactive challenges, and

  • problems to solve. So you can learn by doing. No matter which course you chose Brilliant

  • will guide you from your current knowledge base to where you want to be bit by bit, leading

  • you to fascinating revelations about our universe.

  • If I have inspired you and you want to educate yourself, then go to brilliant.org/RealEngineering

  • and sign up for free.And the first 500 people that go to that link will get 20% off the

  • annual Premium subscription, so you can get full access to all their courses as well as

  • the entire daily challenges archive.

  • As always, thanks for watching and thank you to all my Patreon supporters. If you would

  • like to see more from me the links to my instagram, twitter, subreddit and discord server are

  • below.

This episode of Real Engineering is brought to you by Brilliant. A problem solving website

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