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In this episode.

I have never engineered a building shaped like this one.

A skyscraper unlike any other on Earth.

As people think about it more and more, they realize, wow, that's pretty

incredible. And the pioneering historic innovations.

That is just incredible.

Think about the sheer weight of water those paddles are moving.

That may be impossible.

Possible.

Austin, Texas.

The capital of the Lone Star State is packed with history.

And it's now in the midst of a very modern economic boom.

The city is growing at a rate of 152 people a day.

This population explosion has caused some dramatic changes to the skyline.

Local Austin architect Brett Rode has seen his city expand before his eyes.

Fifteen years ago, this area of Austin was largely forgotten.

There were a couple of apartment complexes down here.

There were some storage yards, some vacant property. It was largely not

known to a lot of Austinites because there just wasn't anything going on

here.

But everything changed in 2005 when some of Silicon Valley's biggest players

decided to make Austin their second home.

The city decided, OK, let's start bringing in some real businesses, some

substantial corporations into downtown.

And from that, when people started to work downtown, they decided, well, gosh,

it'd be great to live downtown, too.

With demand for property downtown at an all -time high, architects like Brett

need to find an engineering solution to the housing crisis.

The cost of land in downtown Austin has just skyrocketed. The more buildings we

have that are coming up, the more valuable that land that's left becomes.

have really no choice but to build upward.

To cater to this growing population.

They have built a one -of -a -kind skyscraper.

The Independent.

Appearing to defy physics, its staggered projecting floors have earned it the

nickname, the Jenga Tower.

I think the Independent is one of the most iconic buildings that we've seen in

recent history.

No one has really attempted a building this shape and this size before.

Located at the heart of downtown,

the Independent stands a gigantic 690 feet tall.

Mimicking the teetering, precarious wooden blocks in the game, portions of

building hang seemingly unsupported hundreds of feet in the air.

Inside, there's enough space to cover over 330 tennis courts.

Parking for over 700 cars and a 170 ,000 liter swimming pool that seemingly

hangs in midair.

Crowned with a stainless steel mesh, it now stands as the city's tallest

structure.

But this ambitious project presents some intimidating engineering challenges.

How do you stop a tall, thin tower from falling over?

Building tall and thin brings its own challenges immediately.

We have to work in a very small footprint to get everything to happen.

that means the structure has to be incredibly efficient.

How do you create extra space over 328 feet in the air?

When you have pieces that stick out hanging off the side of the building,

you get it there? How is that going to attach? That plays a big role in when

you're 200 feet up in the air.

And is it possible to stop the building from swaying in tornado speed winds?

So here in Austin, we do get high, high mile per hour winds.

And designing a building this thin and this tall to resist those wind loads is

very big challenge.

The team behind Austin's tallest building wants to make sure it will be a

feature of the skyline for generations to come.

Usually on a tall building like this, you would see a standard floor plan that

is used throughout from top to bottom.

You sort of just repeat as needed going up, and that is a very, very efficient

way to do it.

Unfortunately, in that scenario, you don't get a lot of variety.

I wanted the Independent to be a very interesting, striking form on the

We wanted this building to touch on the idea that there's something going on

here that's not completely obvious.

Taking the design from Brett's imagination and translating it into a

over 650 feet tall is a job for principal engineer Chris Swanson.

When I first saw it, I thought, wow, this is not something you see every day.

This is really neat. This is really going out on the ordinary and really

to do something that's different.

The construction process starts with the piece of land the Independent will

eventually sit on.

At just over 1 .7 acres, it massively restricts the size of the structure that

can be built on top of it.

The parcel that we're allotted for this building is relatively, it's not a very

large parcel.

Forcing Chris and the team to work hard to find a way to get the most floor

space for their building.

The most area we could get was to create this square.

So that was probably not the best shape that we could have come up with.

The reason why the square shape was not good structurally was that the square

shape in this skinny building created the largest projection area for wind to

hit it.

As anybody knows, you can get a windy day and big wind gusts. They blow stuff

away. You have lawn furniture and it flies over.

So those same forces hit this building, but on a much larger scale.

And when they hit this building on the side that's projected against the wind,

that produces a force.

laterally that we have to resist back down to the foundation.

To overcome these forces, Chris and his team have designed the building around a

central core that contains the elevator shaft, staircases, and maintenance

rooms.

The building core, another way to put it, might be the central spine of the

building. It's providing the primary lateral backbone resistance.

The core on this building is made from cast -in -place concrete.

What concrete does very well, it's an excellent material used in compression.

However, it doesn't work very well in tension.

Unless you have something else, it's going to lose its strength very rapidly.

And that would be definitely something we do not want to see in a very tall

building.

To ensure their core doesn't simply crack and fall apart, engineers must

the pioneering innovators of the past.

The city of Austin has a new structure dominating its skyline.

The 63 -story tall, iconic -shaped, gravity -defying, independent

Below ground, the tower's foundations extend 114 feet into the earth, while

656 feet in the air, a specially designed crown made of stainless steel

tops the roof.

The building's core is responsible for keeping everything standing.

So engineers need to make sure that it's incredibly stable.

In Cincinnati, Ohio, engineer Dan Dickrell is discovering the secrets

long -forgotten building that fundamentally changed the way we build

structures.

So when you think about the history of tall buildings, Cincinnati is not

the first place that comes to mind. But this building right here is historic and

important, just as much as those famous and iconic buildings in New York and

Chicago.

Completed in 1903, the 16 -story Ingalls building used old materials in a new

way that was revolutionary for its time.

It's been empty for years.

Currently under renovation. Now, when it was built, it was the tallest concrete

frame structure in the world.

No one had built anything half as tall out of concrete before because concrete

itself was kind of a problem.

Although it has been used in construction for thousands of years,

fundamental flaw when it comes to building tall.

Concrete as a construction material is really good at resisting compressive

forces. But in a building, you don't just have compressive forces.

You have tensile forces, too, forces that are trying to rip components of the

building apart.

So when concrete's under tension, it does not like it. The material will

and break apart.

And for a building of this type, that's obviously a bad outcome.

Luckily for the engineers constructing the Ingalls building.

one man was working on an ingenious solution.

When English engineer Ernest Ransom moved to the United States in the 1870s,

patented a method for reinforcing concrete that would radically transform

construction techniques worldwide.

All right, so what Ransom came up with is up here at the top of this ladder.

We can see a piece of it. I'm going to pull it down.

This is three bars with a steel rod that gets placed

inside the concrete.

The concrete and the steel work as a team.

The concrete takes the compressive forces and the steel takes the tensile

in bending and enables this magnificent structure to exist in the way that it

does.

Ransom's contribution to steel -reinforced concrete was this, this

structure or spiral.

Now, what this does is when this rebar is placed inside the concrete, it

increases the adhesion or stickiness between the steel and the concrete.

It's effectively the skeleton of this building where the concrete would be the

body.

To find out just how much of a difference Ransom's discovery makes

concrete alone, Dan has traveled to an advanced materials testing lab.

The four -point bend test machine is going to subject these pieces of

just like an overhead beam would be in terms of the top will be compressed and

the bottom will be stretched or extended.

The bottom region is where the maximum tensile forces are going to be, and

that's where we should see crap.

First up is the standard concrete block.

I'm going to slowly increase the load here.

What we have here is a readout that's showing the peak load that's currently

inside this concrete block, and that number's going up and up and up as this

machine presses harder and harder into this block.

And so right now we're at 1 ,500 pounds of force inside the concrete block.

So it's a pretty strong material in and of itself. It's concrete, but at some

point it's just going to have to give up.

And let go.

Our non -reinforced concrete broke at a peak force of just shy of 3 ,000 pounds.

There was so much stress built up inside this concrete block that a crack formed

right at the middle of the bottom surface, and it shot its way up through.

Up next, the steel -reinforced concrete.

Tensile stresses that are in there that rip the concrete apart are now basically

living inside the pieces of steel.

And that's the magic of steel -reinforced concrete.

Because when it goes, it's going to go quick.

And there we go.

So the test with the steel -reinforced concrete, the peak load was around 7

pounds.

substantially larger than a non -reinforced version.

Able to sustain more than double the load than concrete alone, Ransom's

invention was a game -changing material, allowing architects and engineers to

redefine what concrete was capable of.

Back in Austin.

Chris Swanson and his team have taken Ransom's reinforced concrete to new

heights and constructed the city's tallest building.

We're standing currently right now, we're inside the building core. We're

actually inside one of the stair shafts inside the core.

This is actually the outer wall of the building core.

What I'm holding here right now is what we call steel reinforcing, or commonly

termed to as rebar.

This core right here is packed with a bunch of this right here. This is

a number 18 bar, which is the largest size standard bar that you can use

and commonly used in construction these days.

In total, 206 tons of size 18 rebar help keep the independence core stiff

against lateral wind forces.

We would never have been able to do what we're doing here without steel

reinforcing. You really have to use them both in conjunction together.

Use the concrete grate for the compressive capacity, and we use the

as we have right here, to hold the tension. And when those work in unison,

have a very efficient and very durable product that you put together.

Reinforced concrete may have solved the tensile problem, but it's only part of

the puzzle.

So what we're looking at here is a great view of it. This is actually the side,

the south face of the building core, the exterior face.

This may look big to the naked eye or the layman's eye, but for this height of

building, it's a relatively skinny, thin wall.

Building a narrow core allows Chris and the team to maximize living space in

this massive tower.

But it also means that the core no longer provides enough stiffness to keep

building stable.

We could have increased the thickness of this wall. That could have been a

solution to do it.

However, to do that, we would have probably been about out to about here.

have probably added another maybe eight, six to eight inches, if not more, onto

the thickness of this wall. And that would have just taken away from any of

free space that we have standing out here, which is much more valuable space

than... the concrete that we're looking at.

Engineers had to somehow increase the building stiffness without thickening

core.

Their solution can be found over 650 feet in the air.

We ended up integrating a use of what's called an outrigger system, as you see

right here. That's these big steel trusses that you see sticking out.

These are actual big structural members, and they're very integral with the

lateral system of the building.

These outriggers right here basically link that central backbone core, as you

think of it. They link it to the outer columns of the building floor plate.

So if we were to take that analogy as a skier, my body... My skinny body, that

would be the core. That would be the core as we were doing.

As I have my arms sticking out like this, those would be my outrigger

And then the ski poles, the imaginary ski poles as we would have, those would

the columns, the outer columns, so that when I go like this, I can stay. And

that's exactly what we have here.

Believe it or not, outriggers are used more often, but people don't see them

very often.

And what's unique about the Independent that I really love is that these are

exposed.

It's a very efficient and effective design that will stand here for a long,

time to come.

The Independent is the tallest residential tower in the western United

Offset tiers extend over 16 feet from the face of the building, defying

traditional skyscraper form and giving the structure its unique appearance.

But now, engineers will face one of their toughest challenges.

Basically, we had to create space out of thin air in the middle of the building.

So that was a huge challenge.

As they attempt to defy the laws of physics.

In Austin, Texas, a rapidly expanding population is forcing architects

and engineers to reach for the sky and build the

city's tallest skyscraper.

When complete, the Independent will be home to more than 360 people.

With condos ranging in size from over 650 square feet to almost 11 ,000 square

feet on the 58th floor penthouse.

But accommodating so many homeowners presents a problem for architect Brett

Rode.

We have so many people living here. We need to find places for everyone to

gather. We need to find places for people to get out of their apartment and

experience the views.

We thought the best place for that sort of thing would be kind of in the

midpoint of the building where people could kind of come from the taller part

the building and from the lower part of the building to meet.

Residents have been promised a wide range of amenities, including a gym and

private movie theater.

But without enough space to fit everything in the middle of the

and his team face a challenge.

We could have gone taller to accommodate some of those important needs of the

residences, but we really felt it was much better to have everything located

one floor.

So, could the solution to this engineering challenge be found in the

of the past?

In London's world -famous West End Theatre District, engineer Rhys Morgan

getting a behind -the -scenes look at one of the city's most impressive

buildings.

Oh, wow, look at this. This is absolutely incredible.

It's an enormous space.

It really makes me want to dance and sing.

It's really fabulous.

Opened in 1904, the London Coliseum remains a shining example from the

age of British theatre design.

When the Coliseum was built, the economy was booming and audience numbers were

up, and so theatre owners and producers were really keen to cash in on this

extra demand.

Entrepreneur Oswald Stoll wanted the Coliseum to be the largest and most

theatre in the city.

He proposed four tiers of seating to accommodate an audience of 2 ,000

but the tiers would need to be supported by columns or pillars.

The problem with columns or pillars is that they take up valuable space for

seating and they restrict the views of the customers behind.

To ensure the show could go on, Stoll turned to Frank Matcham, one of the

leading theater designers of the time.

But the Coliseum presented a challenge on a scale even he'd never encountered

before.

The balcony floors need to be supported by these columns that I've made out of

wood. And the weight of the floors and the people on them are transferred

through the columns to the ground.

The problem is, the theatre -goers sitting behind the columns get a

view of the stage and so get a bit grumpy.

And also the columns take up valuable space that eats into stalls profits.

But we can't just remove the columns because this happens.

I love that.

So we need to find another way to support the flaws and remove the

To overcome the problem, Matcham made use of an engineering principle known as

cantilevering. Now with cantilevering, instead of using columns to support the

weight of the floors, you use a steel beam inserted through the floor, and

beam connects directly to the load -bearing wall of the building.

Now this floor is supported by the wall, the bottom of it is under compression,

it's being forced together, whereas the top of the floor is under tension, it's

being pushed out.

But both the compressive and the tension forces are being pushed through the

steel beam back into the supporting structure.

The weight of the floor and the theatre -goers is now being entirely supported

by the beam and the load -bearing wall of the building.

So the audience members get great views, and Stoll gets to put in more seating,

increasing his profits.

Matcham's cantilevered balconies were so successful that he patented his method,

allowing him to stay at the forefront of theater design.

Wow, look at this.

I'm on the balcony on the very top floor, and the view is just magnificent.

From here, you can really see how incredible Matcham's design was using

cantilevers. There are no columns obstructing the view for me or any of

other people on this level, nor, for that matter, the sections below and

that. I mean, it really is phenomenal.

And it's still the biggest theatre in London.

And that is a testament to Frank Matcham's engineering genius.

Back in Texas, the team has taken Matcham's cantilever technique and

to the extreme.

It's completely void beneath us. We are literally 300 feet up in the air at this

location.

The Independent, Austin's tallest residential tower, includes spacious

amenities for residents to enjoy.

But large support columns in the center of the building would take up a

considerable amount of space. So engineers got creative and designed the

building with vast offset tiers, which seemingly defy the laws of physics and

give the Independent its definitive shape.

Shane Tanner is the engineer responsible for creating space out of thin air.

So this is the level 34. This is the amenity space where you have this large,

about 30 -foot cantilever that juts out from the building.

Measuring a massive 33 feet long by 89 feet wide, the cantilevered amenity trot

has created a gigantic amount of additional space.

housing the lounge, gym, and private movie theater.

So right here is what we call an expansion joint, but this also marks the

where the concrete structure stops and the steel structure starts. This is

the whole cantilever begins.

This area over, it's completely cantilevered out. We are literally 300

in the air at this location. It's completely void beneath us. There's no

directly underneath of us on this area at all.

Ensuring that this huge piece of the building doesn't fall onto the street

requires three massive steel trusses weighing nearly 10 ,000 pounds and some

precision lifting.

Oh, yeah. Look at this, guys. This is really cool.

Once in place, the team has to join the trusses to the building itself.

So all these trusses connect back to the mega columns, and you can see right

here the painted collar.

That's a giant steel collar that's embedded into the megacolm. And what we

is we interwoven steel pipes with the reinforcement to make a nice rigid

connection. And each one of those collars, it's about 6 ,000 pounds for

really huge, beefy collars.

Due to the size of the cantilevered space, engineers must use three full

trusses.

Steel members at the top and bottom of each one attach to vertical and diagonal

struts that handle the compressive and tensile loads.

Anchored back to the building's mega columns, they provide the floor's

and structural support.

Finally, they're wrapped in concrete and glass, finishing the immense

cantilevered floor space.

So this cantilever portion created about 25 % more square footage on this

amenity level.

And by implementing a similar engineering solution on other floors,

the team are able to cantilever out additional sections of the building,

it its individual shape.

So in the condos, we use the same tension rod and compression strut

We have one tension rod.

that connects back to a megacolumn. And we have one compression strut that's

used as a way,

as a fail -safe, if someone cuts one of the tension rods, it will transfer down

to another tension rod. So all these tension rods in the condos are actually

designed to hold up three floors, not just one floor.

Engineers may have found a way to create space out of thin air, but now they

face their most difficult challenge.

So in a high wind event, any building that you see may move depending on the

range of an inch to maybe two inches or even farther, maybe even six inches.

As they aim to defy Mother Nature herself.

If you spend a few million dollars on a condominium to be up in here, the last

thing you're going to want to do is feel like you're seasick.

To overcome this challenge, engineers will need to look for a solution in an

unlikely place.

Oh, no, it's moving all over the place now.

And even they've gone now.

The Independent.

Austin's tallest luxury residential skyscraper.

Nicknamed the Jenga Tower.

Its staggered, gravity -defying projections have redefined the skyline,

taking the crown as the city's tallest building.

But constructing a tower over 650 feet in the air pits engineers against

one of their biggest rivals, the weather.

Wind conditions in Austin can range quite a bit.

Luckily, on a day -to -day, the wind conditions are relatively low, and

how it normally is for the case. However, you can get gusts easily in the

of, you know, 60 to 80 miles an hour wind.

And occasionally, hurricanes and tornadoes can batter the city.

You can get wind gusts up to, from the 90 mile an hour, they might go up to the

300 mile an hour gusts.

or even higher.

So in a high wind event, any building that you see may move depending on the

range of an inch to maybe two inches or even farther, maybe even six inches.

The higher up the building you go, the greater the amount of movement.

You may see your pictures.

They may move a little bit, or you may see some rocking or something of that

nature.

And it's not just the furniture that's at risk.

Where you have high winds that gust, you don't want people to feel like they're

in a boat up in the top of the building and get sick.

Engineers will have to factor motion into the independence design. But

this is one problem that's been overcome in the past.

Physicist Andrew Steele has come to the Coast Laboratory at the University of

Plymouth in the southwest of England to discover a pioneering piece of marine

engineering.

Wow, look at this thing power up.

That is just incredible.

Think about the sheer weight of water those paddles are moving.

This massive tank is a maritime... scale model testing tank.

You can put scale models of ships in here and expose them to some of the

roughest conditions they could ever experience out at sea.

In the 19th century, as the British Navy transitioned from wooden hulled boats

to iron, conditions like these caused them a major problem.

This modernization in ship design meant that they were suddenly much more

susceptible to what's called rolling motion.

You've got these guns, you're trying to precisely target them on an enemy

vessel, but if the whole platform your gun's on is just wobbling from side to

side, how on earth are you going to get a shot on target?

Andrew is taking to the water to demonstrate just how devastating this

can be.

So I'm just taking my boat for a walk, as you do, all aboard the HMS Orange.

And what we're going to do is pop her just in the middle of the tank here.

And then those huge paddles down there are going to send waves towards this

thing. And we're going to see how the boat and her passengers fare.

Good luck, guys.

There's nothing on that ship that's going to try and stabilise it if it does

hit by a wave. So even fairly gentle waves are going to put our passengers in

great deal of peril.

OK, I think we're ready.

Start the waves.

Feeling a bit nervous for my little guys out there right now.

There we go. You can see it just starts to roll about a little bit in the water.

Oh, we've already had one succumb to sea sickness.

And two, it's not looking good for those passengers.

What's crucial here isn't necessarily how big the waves are, it's how fast

arrive. And if we can get them to arrive at just the right frequency, we can

start to get the boat to roll bigger and bigger, get its resonant frequency.

And if we can hit that resonant frequency, then the boat's really going

rolling and it's curtains for those guys on board.

In the 1880s... Renowned naval architect Philip Watts used a Navy warship to

study the effects of using water to reduce this rolling motion at sea.

As a result of Watts' study, the HMS Inflexible was fitted with a stability

anti -roll tank. And I've got a modern reimagining of one of those here.

Got a marking on the side there that I'm aiming for.

That's about right.

So there we go.

And it's absolutely amazing to think that this could possibly make any

difference. But what we're going to do is just bombard it with that same

succession of waves at the same frequency.

Got our passengers safely back on the ship.

Amazingly, they've agreed to go again.

Our tank is full of water, so let's make some waves.

And here come the waves, rolling ominously out over the surface of the

You can see the water flushing around in our tank. Oh, we've lost a little bit.

Now, every time one of those waves hits it, it floshes the water to one side of

the tank.

And that means that when the ship rolls back in the other direction, that water

has already got momentum, which means that can counteract the roll of the

And it keeps the whole thing much more stable.

You can see the ship is actually rolling far less than it was before, exactly as

the physics would predict.

Before everyone was in the water, apart from one of our sailors, But now they're

all sat, probably having quite a nice time.

The stability tank was a revolution in marine engineering.

Watts' stability tank showed that a liquid damper could stop ships from

experiencing this terrible rolling motion while they're out at sea.

And modern adaptations with this design are used as part of the stability

systems in some of the largest ocean -going vessels in the world today.

Back in Austin, engineers have taken the design behind Watt's maritime solution

and transferred it on to land.

But it will take some legwork to reveal its secrets.

This is great. I've never been up here before.

This is really impressive.

Soaring 650 feet above the city, the Independent is the tallest building in

Austin, Texas.

But to ensure that this tall tower will be able to withstand fierce winds and

severe weather, engineers had to use an unlikely material.

So we are up here on level 60 at the very top of the building, and we are in

room for the damper tank, and that is what we're looking at right here. This

a liquid sloshing damper.

This helps keep the motion in check. We use this tank to basically slow down the

motion of the building going from one end to the other. It keeps that motion

check so people don't feel seasick.

Over 30 feet wide and 10 feet high, the damper tank contains 50 ,000 gallons

of water.

Constructed from modular fiberglass sections.

On the inside, vertical steel plates known as baffles help to keep the

movement under control.

What these baffles do is the baffles prevent the water from coming back very

quickly if it moves from one side to side.

So if the building is moving in a direction, the water is pushed up

these vertical baffles and it holds its place over here instead of going to the

other side of the tank.

But to truly appreciate the engineering brilliance behind the tank, you have to

venture to a spot very few people will ever see.

Oh, wow.

This is great. I've never been up here before.

This is really impressive.

We're standing right now on the top of the independent of the roof. We are.

As we sit right now, we are on the currently the tallest occupiable point

Austin as we sit right now.

So what we're going to be looking at here, this is the hatch to basically

We are looking inside the damper tank.

We can see right here, you can see the water level and you can see some of the

baffles. You see one edge of the baffle right there, and you can see it's just a

piece of fiberglass. So all it is is that fiberglass wall.

And water is about two to three feet from the top, so I guess we are

doing good.

The Independent has reinvented the Austin skyline.

And being part of building such a unique structure is a career -defining

opportunity for the team behind it.

This project has been really amazing.

I'm just so gratified and feel so lucky to have been a part of it.

This extraordinary tower has redefined a city.

Its central concrete core, outriggers, and eight mega columns provide the

building strength.

Enveloped in glass.

The unique cantilever design provides over 360 homes and 2

,800 square feet of amenity space.

It's a feat of engineering few thought possible.

It's constantly giving me...

new perspective.

It's constantly giving me new hope. It's definitely been a centerpiece and

enjoyment of my career.

By looking to great pioneers of the past for inspiration,

adapting their ideas,

refining their design, and overcoming monumental challenges.

So when you start out designing a project like The Independent, You don't

quite where it's going to lead.

We came up with something that was pretty amazing.

Engineers have constructed something radical and succeeded in making the

impossible possible.

You can safely say that this building stands out. You've got the Empire State

Building, you've got the Sears Tower, you've got those other buildings in

Chicago. These are iconic buildings of cities, and that's what we've created

here. And when people think of Austin, they're going to know that this building

is part of Austin.

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