Category Archives: Engineering

Raising Cranes in Skyscrapers

Tower crane on top of building under constructon in Manhatan, NY
iStock

Look up! It’s a bird. No, it’s a plane. No, it’s a tower crane! That’s the official term for a crane (sometimes called a ‘derrick’) placed onto under-construction skyscrapers. But how do they get there, and how do the workers raise the crane after each floor is completed? Here, we will delve into the intricate steps involved in accomplishing this amazing engineering feat.

The Jump

Raising cranes, technically called “crane jump” or what construction workers call “jump the crane,” is a fascinating engineering feat that involves meticulous planning, specialized equipment, and skilled labor. 

Although this sounds sophisticated, it is a process that is done on a routine basis, especially in cities like New York, where skyscraper construction is a daily routine.

Jumping the crane is a crucial step for facilitating the construction of tall buildings efficiently and safely. 

Dual collage of Vandebilt Building in NYC under construction
Vanderbilt Building. 42nd St. NYC showing tower cranes during its construction. Photo: SMS

Where’s My Crane?

The first step is selecting the appropriate type of crane for the job. Below is a list of the major types of cranes used in construction.

Mobile Cranes

Mobile cranes, as the name suggests, are mounted on tracked vehicles, allowing them to be easily transported to different locations. 

Crawler Cranes

These cranes use tracks instead of wheels, providing mobility on uneven or soft ground surfaces. They are often used in heavy-duty lifting operations such as bridge building and equipment installation.

Tower Cranes

Most famous for the construction of tall buildings, especially supertalls. 

Overhead Cranes

Also known as bridge or gantry cranes, they are installed on elevated runways or gantries within a building or industrial facility and are commonly used in manufacturing and warehouses.

Jib Cranes

These compact lifting devices with a vertical mast or pillar are commonly used for lifting materials in workshops, loading docks, and assembly lines. Not to be confused with the jib erected to a tower crane on skyscrapers.

Telescopic Cranes

These machines contain telescoping sections that can extend or retract to adjust the reach and lifting capacity.

Floating Cranes

These are specialized cranes usually mounted on barges, allowing them to operate on rivers, lakes, or ports. They are used for lifting heavy loads onto ships, offshore construction projects, and marine salvage operations.

Loader Cranes

Also known as knuckle boom cranes, loader cranes are equipped with hinged booms that resemble knuckle joints. This design allows the crane to fold and unfold, enhancing maneuverability and reach. Loader cranes are commonly used for loading and unloading cargo.

Skyscrapers Choice

From the choices above, the Tower Crane is used for skyscraper construction. It is characterized by its tall vertical mast and horizontal boom, which can rotate to lift and move heavy loads across the construction site. This makes it the perfect choice for the construction of tall buildings.

Assembling the Crane

Once the crane type is chosen, the construction team begins assembling the structure on the ground. This typically involves erecting the tower mast section by section, securing it with bolts or pins, and attaching the horizontal jib or boom. Each crane section is carefully hoisted into position using smaller cranes or hydraulic systems.

Photo of a jib crane
Jib/Boom Section fo a Tower Crane. iStock

As the crane assembly progresses, special attention is paid to ensure the stability and structural integrity of the crane. Counterweights are strategically placed to balance the crane’s load capacity and prevent tipping. Additionally, anchoring systems, such as tie-downs or concrete footings, are installed to secure the crane to the ground and provide stability during operation.

Safety measures are paramount throughout the crane-raising process. Construction workers receive thorough training on its assembly, and strict safety protocols are enforced to prevent accidents and injuries. Quality control inspections verify that each crane component meets safety standards before being put into service.

Lifting the Crane into Position

Photo of tower cranes on top of building under construction in lower Manhattan
4 World Trade Center. 150 Greenwich Street, NYC, under construction. SMS

Once the crane is fully assembled and tested, it can be hoisted into position. This is typically accomplished using hydraulic jacks or a climbing system that incrementally lifts the crane to the desired height. As the crane ascends, additional mast sections may be added to extend its reach as the building grows taller.

Installing the crane at the correct location maximizes its efficiency and effectiveness. Engineers carefully analyze factors such as building layout, wind patterns, and logistical considerations to determine the optimal placement for the derrick. This ensures the crane can reach all construction site areas while minimizing interference with other construction activities.

All Set

Once in position, the crane becomes an essential tool for the construction process, lifting materials, equipment, and personnel to various building levels. Skilled operators control their movement with precision, coordinating with ground crews and construction workers to safely transport loads to their designated locations.

As the skyscraper’s construction progresses, the crane may need to be modified or repositioned to accommodate changing project requirements. This could involve adding or removing mast sections, adjusting the boom length, or relocating the crane to a different part of the site. These adjustments require careful planning and coordination to minimize downtime and ensure continued productivity.

On Top of the World

Collage of WTC Freedom Tower under construction
One World Trade Center (Freedom Tower) is under construction. (L-R) March 2010 and November 2011. Photo SMS

Once assembled and set into place, the lifting begins, which can be steel beams, concrete sections, or other large, heavy items. 

The Take Down

Eventually, as the skyscraper nears completion, the crane will be disassembled in a reverse process, as it was erected. Each component is carefully lowered to the ground using hydraulic systems or smaller cranes and dismantled for transport to the next construction site or storage facility.

Conclusion

If you live in a big city like Chicago or New York, you no doubt have seen these tower cranes in action. Now, you can appreciate the complexity and intricate process needed, along with the skilled labor and specialized equipment.

From selecting the right crane for the job to safely assembling and operating it on the construction site, every step is essential for ensuring the successful completion of tall building projects. So, the next time you look up at a skyscraper, you can credit the tower cranes and the construction workers who put it all together.

What are the Major Components of Building a House?

Wood frame house under construction

Suppose you want to build a house for yourself and your family. What is involved? It is not just about getting the wood or metal components and assembling them. A lot more is involved, starting with planning. Let’s take a look.

The Design

First, before you hire anyone, you need to decide the architectural style you want. Will it be a colonial, Tudor, Georgian, or contemporary? Or perhaps you are looking for a more traditional or old-fashioned look, such as Victorian or Art Deco? 

When you decide, the next step is to visit an architect. This professional will propose the design and layout based on your specs, such as the number of bedrooms and baths, and any specific requests, such as a library, movie room, gym, or maybe vaulted ceilings with a skylight over the dining room.

The architect will also oversee all the structural components to ensure the building’s stability and safety and begin the procedure for obtaining the necessary permits and approvals from local authorities. You will probably review several designs and floor plans before deciding.

The Builders

Once the design is complete, you will need to find the building developers. This company will build your house based on the architect’s plans and specifications.

The Foundation

The building developers prepare the foundation before the first brick is laid. They construct the foundation walls, which support the structure. Usually, this consists of applying a combination of wood and concrete to line the walls, but it may include other elements as well.

Additionally, a rebar is used to reinforce the concrete to withstand the everyday stresses of tension (pulling apart). If the concrete is not mixed correctly, or the rebar/concrete assembly is flawed, cracks can result in the concrete, compromising the integrity of the structure and resulting in significant costs to fix, as well as posing a danger to those who are in the building.

Utilities

The developers will connect the water, sewer, electricity, and other utilities required for the house structure.

Framing

House under construction showing frame structure

So far, if you look at how your home is taking shape, all you will see is concrete and wood along a hole in the ground. It’s not very pretty, so you will need to come back when the framing begins, which refers to the house’s skeleton that resides above the foundation. 

You will see the structural frame, which is the 2x4s that support the walls, and then the siding will be installed. Wood or concrete are the most common, and finally, the sheet rock will cover the framework. 

Windows and doors and any finishing details, such as a specified interior trim, come next. 

Plumbing and Electrical Work

Photo of electrical wiring in an offic

Interior Finishing

    • Flooring: Putting in the chosen flooring material (e.g., hardwood, carpet, tile).
    • Cabinetry and Countertops: Installing kitchen and bathroom cabinets and countertops.
    • Painting and Wall Coverings: Applying paint or wallpaper.
    • Trim and Molding: Adding decorative elements.

      Fixtures and Appliances

    • Plumbing Fixtures: Installing sinks, faucets, toilets, and showers.
    • Lighting Fixtures: Adding light fixtures throughout the house.
    • Kitchen Appliances: Installing ovens, refrigerators, and other appliances.

      Landscaping and Exterior Elements

      Landscaping: Designing and planting the garden or yard.

    • Driveway and Walkways: Creating paths and driveways
    • Outdoor Features: Building decks, patios, and other outdoor spaces.
  • Final Inspections and Tests:
  • Building Inspections: Authorities check the house for compliance with building codes.
  • Quality Assurance: Ensure all systems and components are functioning correctly.
  • Occupancy and Move-In:
  • Obtain a Certificate of Occupancy: This allows you to occupy the house legally.
  • Move-In: Finally, you can move into your new home.

Building a house is a significant undertaking, and it involves various professionals, including architects, engineers, contractors, electricians, plumbers, and more, to ensure the project’s success. The specific steps and components can vary based on the type of house, location, and individual preferences.

 

 

What’s the Difference Between a Building Spire and Antenna?

Introduction:

Many skyscrapers may feature protruding elements on their roofs that serve different purposes. Two common rooftop structures are spires and antennas. While both structures may appear similar from a distance, they have other functions and designs. This essay will explore the differences between building spires and antennas.

The Feud Between Spires and Antennas

One World Trade Center - Freedom Tower photographed from Broadway
One World Trade Center – Freedom Tower looking south from Broadway. Photo SMS ©

When the new One World Trade Center (AKA Freedom Tower) in New York City was completed, the owners laid claim that this was the tallest building in the western hemisphere, rising to a symbolic height of 1,776 feet. The number represents the year the Declaration of Independence was created.

Willis Tower Chicago
Willis Tower. Photo: Photos of a Lifetime ©

But all is not rosy when the owners of the Chicago Willis Tower had something to say about it. They claimed that the 408-foot steel attachment that was placed on the top of the Freedom Tower should not count and subsequently, the 1,451-foot Willis Tower should still be considered the tallest building in the western hemisphere.

Interesting note: The Empire State Building has a spire and an antenna!

Enter The Council of Tall Buildings


Someone needed to step in and resolve this and the international non-profit Council of Tall Buildings did just that and their conclusion was that the Freedom Tower is the tallest

Reason is that there is a difference between a spire and antenna and spires count. Antennas don’t, of which they concluded that One World Trade Center has a spire.

Now let’s take a look and see why this is the case.

Function

The primary function of a building spire is to enhance the aesthetics of the structure. Spires can add architectural interest to a building and make it stand out in a cityscape. They come in different shapes and sizes and can be made from various materials, such as metal or stone. Spires can also have religious or symbolic significance, as they are often found in churches or other historical buildings.

Antennas, on the other hand, have a functional purpose. They are designed to transmit or receive electromagnetic waves, such as television or radio signals. Antennas can also be used for communication purposes, such as transmitting mobile phone signals or internet data. They are typically made of metal and are shaped to optimize the reception or transmission of waves.

Design 

Spires and antennas have distinct designs that reflect their functions. Building spires are often ornamental and decorative and conform to the building’s architecture or aesthetic design. 

They can be designed in various shapes and sizes, such as a pointed Gothic spire or a round domed spire. Spires are typically made of materials that can withstand weather and environmental factors.

Antennas, on the other hand, have a practical design that is optimized for their function. The shape of an antenna is critical to its performance in capturing or emitting electromagnetic waves. 

Antennas can be designed in different shapes, such as a Yagi antenna or a dipole antenna, depending on the specific frequency range they are intended to operate within. The size and placement of an antenna are also crucial factors that can affect its performance.

Location

Spires and antennas are located on different parts of a building. Spires are typically located at the top of a building, either on the roof or on a tower. They are often used to create a distinctive silhouette or to draw attention to the building. Spires are usually visible from a distance, which makes them an essential part of a building’s architecture.

Antennas, on the other hand, can be located anywhere on a building’s roof or facade. The location of an antenna depends on various factors, such as the type of signals it is designed to capture or transmit and the obstacles in the surrounding area. Antennas can also be located on poles or towers outside of a building.

Regulation

The regulation of spires and antennas differs. Building codes typically regulate the design and construction of spires. There may be height restrictions or other regulations that limit the size or shape of a spire. Spires may also be subject to aesthetic guidelines to ensure they fit in with the surrounding architecture.

Antennas, on the other hand, are subject to a different set of regulations. In many countries, the construction of antennas is regulated by government agencies, such as the Federal Communications Commission (FCC) in the United States. These agencies are responsible for ensuring that antennas are safe and do not interfere with other electronic devices or signals. Antennas may also be subject to zoning regulations that limit their size or placement.

Conclusion

In summary, while building spires and antennas may appear similar from a distance, they have different functions, designs, locations, and regulations. Spires are decorative elements that enhance the aesthetics of a building, while antennas are functional structures that capture or emit electromagnetic waves. 

The design of a spire is ornamental, while the design of an antenna is optimized for its function. The location of a spire is typically on the roof or tower of a building, while the location.

And there lies the reason why the Freedom Tower stands to be the official tallest building in the western hemisphere.

 

Suspension Bridges: How are They Constructed

Poyab Bridge under construction, Freiburg, Switzerland
Poyab Bridge under construction, Fribourg, Switzerland. Photo: iStock

Suspension bridges are among the most impressive engineering feats, with their long spans and elegant designs. These bridges rely on the strength of cables and towers to support the cables which provide safe passage over rivers, gorges, and other obstacles.

In this article, we will explore how suspension bridges are constructed.

Bridge Suspension Cables

Cables on Royal George Bridge - Colorado
Suspension Cable on Royal George Bridge – Colorado. Each cable is made up of 2100 galvanized steel wires. Photo: ©SMS

Once the towers are in place, the cables can be installed. The cables are assembled on the ground and then lifted into place using cranes or other heavy machinery. The cables are anchored to the towers using large steel plates, which are bolted to the tower and embedded in the concrete foundation. The cables are also anchored to the ground using massive concrete blocks, which are buried deep below the surface of the earth to provide a secure anchor point.

Suspension cables are an essential part of the suspension bridge design, which hold up the load (bridge deck or road) and are braced by towers on each side of the bridge. Anchoring the cables to the towers, or sometimes to the ground on both sides, enables the load to stretch across the entire span of the bridge without any further bracing required (e.g. truss or arches holding it up).

The cables are typically made of high-strength steel wires woven together that act as one unit. These cables can weigh thousands of tons and must be anchored securely to the towers and the ground.

The tension in the main cables is transferred to the suspension cables, which then transfer the weight of the bridge deck to the towers and anchorages at the ends of the bridge.

The towers provide additional support to the bridge and help to distribute the weight of the bridge evenly.

In the photo above of the Royal Gorge Bridge in the Rocky Mountains, Colorado, each of the cables consists of 2100 galvanized steel wires.

Bridge Deck

With the cables in place, the next step is to construct the bridge deck. The deck is typically made of steel or reinforced concrete and is suspended from the cables using hangers. The hangers are attached to the cables using large steel pins and are spaced at regular intervals to provide support for the deck. The deck is often assembled on the ground and then lifted into place using cranes or other heavy machinery.

Once the deck is in place, the final touches can be added. This includes the installation of guardrails, lighting, and other safety features, as well as the application of the final coat of paint. The bridge is then inspected to ensure that it meets all safety standards and is ready for use.

Summary

In conclusion, suspension bridges are an incredible feat of engineering, requiring meticulous planning, precision construction, and rigorous safety testing. The construction process involves the careful placement of towers, the installation of massive cables, and the suspension of the bridge deck. Despite the challenges involved, suspension bridges have become an iconic symbol of human ingenuity and technological advancement, connecting people and places all over the world.

The Freedom Tower – From Construction to Completion

Overview

One World Trade Center - Freedom Tower photographed from Broadway
One World Trade Center – Freedom Tower looking south from Broadway. Photo: SMS Photos of a Lifetime ©

From tragedy to triumph, a tower soars 104 stories, 1,776 feet high, representing the year the Declaration of Independence was signed.

One World Trade Center (AKA The Freedom Tower) opened to businesses on November 3, 2014, and the three-story observatory, which opened on May 29, 2015, invites visitors to a spectacular view of the New York skyline.

Skidmore, Owings & Merrill, famous for designing some of the most notable modern tall buildings throughout the world, were the primary architects, under the supervision of designer David Childs. The firm, also known as SOM, was the architect of the Burj Khalifa and Chicago’s Willis Tower (formerly the Sears Tower).

The Preliminaries

Soon after the tragic destruction of the original World Trade Center (Twin Towers), the Lower Manhattan Development Corporation initiated proposals for the reconstruction of a new tower, as well as a plan to memorialize the victims of the September 11 attacks. 

When the public rejected the first round of designs, a second, more open competition took place in December 2002, in which a blueprint by Daniel Libeskind was selected as the winner. This design went through many revisions, mainly because of disagreements with developer Larry Silverstein, who held the lease to the World Trade Center at that time.

Construction began on April 27, 2006, but not after continuous delays and ongoing bureaucracy, including disputes between the Port Authority of New York and New Jersey and the developer Tishman Realty & Construction. The Tishman construction firm was famous for its participation in building some of the tallest buildings in New York City, including the original World Trade Center complex and the John Hancock Center in Chicago. John Tishman died on February 6, 2016.

Security Preparations

Bird's eye view of "ground zero" after the 9/11 attacks and before construction of the Freedom Tower
Bird’s eye view of “ground zero” after the 9/11 attacks and before the construction of the Freedom Tower. Photo: SMS – Photos of a Lifetime ©

No doubt that security was a prominent concern in the design and construction of this tower, and terrorism was indeed a major consideration. 

No one was more concerned than the NYPD, and after many debates and delays, the final proposal for the Freedom Tower 11-Year was approved and shown to the public on June 28, 2005, with a 187-foot base of concrete added.

Additionally, the building had installed stainless steel panels and blast-resistant glass. The Freedom Tower is designed to withstand earthquakes and has an elaborate security facility integrated within it.

In addition to 24×7 monitoring, there is a high-tech security system that includes video analysis in which computers would alert security personnel to abnormal situations automatically.

There are additional security apparatuses that have been installed, but their actual function has not been made public. What is known is that there are radiation detectors abound in lower Manhattan and the NYPD Hercules Team is ready at a moment’s notice.

Building the Skyscraper

On November 18, 2006, 400 cubic yards of concrete were poured onto the building’s foundation.

Foundation of One World Trade Center
Construction of the foundation of One World Trade Center. Photo:  SMS – Photos of a Lifetime ©

On December 17, 2006, a ceremony was held in Battery Park City, with the public invited to sign a 30-foot (9.1 m) steel beam. The beam was welded onto the building’s base on December 19, 2006. Construction was slow but continuous. 

Collage of WTC Freedom Tower under construction
One World Trade Center (Freedom Tower) under construcion. (L-R) March 2010 and November 2011. Photo SMS

In 2012, workers installed the steel framework at the top of the tower to support the 408-foot spire. The spire was fabricated as 16 separate sections at a factory near Montreal, Quebec, and was transported by barge to New York City in mid-November of that year. 

On May 10, 2013, the final component of the skyscraper’s spire was installed, making the building, including its spire, reach a total height of 1,776 feet, representing the date of the Declaration of Independence.

Negotiating the Wind Forces

Optimizing One  World Trade Center for high winds was unique as the tower’s design included a geometrical shape that helps reduce exposure to wind loads.

Additionally, the core has reinforced concrete which provides the main support against resistance to the wind forces and other forces of nature.

The Observatory

View from Freedom Tower Observatory
View from Freedom Tower Observatory of downtown Manhattan taken on opening day. Photo:  SMS – Photos of a Lifetime ©

The One World Trade Center observatory opened on May 29, 2015, and is currently the highest of the four observatories in the city at  1,268 feet.

There are three floors, including exhibits and a restaurant.

The most convenient way to purchase tickets would be to purchase them online.

 

Surrounding Area

World Trade Cener North Tower Reflecting Pool
World Trade Center North Tower Reflecting Pool. Photo: Wikimedia Public Domain

Visitors who come to the Freedom Tower should also visit the 911 Memorial, which is a tribute to the 3,000 people who were lost, including the first responders.

The memorial contains the footprints of the former Twin Towers. It has continuous running water over two one-acre pools, one for each of the towers, called “Reflecting Absence“, signifying the physical void left by those who were lost. 

Skyscraper Wind Forces and How to Overwide Them

NYC Midtown Skyline Western View
NYC Skyline Looking West from Long Island City. Photo: Photos of a Lifetime ©

Overview

Skyscrapers are defined as being at least 330 feet (100 meters) high with supertalls classified as 984 feet (300 meters) and mega tall at 1,968 feet (600 meters) or higher.

From the Burj Khalifa in Dubai to the Shanghai Tower in China and the Empire State Building in New York, there is no doubt that these structures are a marvel of modern engineering and they stand as a testament to human ingenuity and perseverance. For architects and engineers, the challenge to design them is complex.

From the foundation to the roof, they are carefully planned and executed by scivi engineers, which might take years to complete before even one brick is laid down. Considerations towards building codes, structural stability, aesthetics, and of course economics are primary factors to be studied.

Exploring the making of skyscrapers is an exciting journey for anyone interested in how tall buildings are constructed. This article is a credit to the dedication to the architects and engineers who build them.

Enter the Forces of Nature

Burj Khalifa
Burj Khalifa, Dubai, UAE – Tallest Building in the World. Photo by Wael Hneini on Unsplash

Wind loads (wind forces) that hit the buildings can cause them to sway. The higher the building is, the more wind it will be subject to.

Skyscrapers will sway and can easily move several feet in either direction.

To reinforce the structure to withstand these winds, there are several options that engineers will use.

 

Empire State Building – A Prime Example of Mitigating Wind Forces

Empire State Building
Photo by Ben Dumond on Unsplash

Before we delve into the engineering specifics, let’s get familiar with the general idea of how buildings suppress wind forces and what better example to use than the famous Empire State Building?

Most tall buildings use multiple methods to mitigate strong winds, so let’s take a look at what engineers have done with this 1,472-foot-high iconic structure.

  1. Streamlined shape: The building has a tapered shape that reduces wind resistance and helps to distribute wind forces evenly across the building. More commonly known as setbacks.
  2. Wind bracing: The building has a series of steel braces that run diagonally between the exterior columns, which helps to provide additional support and stability against wind forces.
  3. Corner columns: The building’s corner columns are larger and stronger than the interior columns, which helps to distribute wind forces more evenly throughout the building.
  4. Tuned mass damper: The building has a large pendulum-like device called a tuned mass damper located on the 58th floor. The damper helps to counteract wind-induced building oscillations by moving in the opposite direction of the building’s sway, effectively damping out the oscillations.

Now let’s take a look at the process from start to finish.

Designing the Structure 

3D rendering of a modern building with construction using CAD software
3D rendering with construction specifications using CAD software. Photo: iStock

Economics always comes into play, so whatever the planned design is, it must be within the developer’s budget. Architects use computer-aided design (CAD) software to create 3D models of a building.

Usually created on networked desktop computers, CAD is used primarily for analyzing and optimizing a building’s design.

Of course with skyscrapers, there may be hundreds of CAD diagrams that would be needed. The software includes the building codes that they must follow.

Building the Foundation 

Foundation of One World Trade Center
Foundation of One World Trade Center 4/6/2008. Photo: Photos of a Lifetime ©

It should go without saying that structural stability is of the utmost importance and the foundation is the first step in helping to buttress the building from the forces of nature to which these buildings may be subject. 

Beginning with the foundation, engineers must determine if the soil below the building is strong enough to support the structure. A good example is in New York City where there is solid bedrock that makes it perfect for the construction of skyscrapers. 

Rebar at construction site on Long Island
Rebar ready for pouring of concrete at a construction site. Photo SMS ©

Steel and concrete are the most commonly used materials for foundations. Concrete is strong under compression, but not as strong under tension, and in its pure form, it is unsuitable to withstand the stresses of the wind forces and vibrations,

To compensate for this lack of tensile strength, workers pour a liquid concrete mixture into a wire mesh steel frame, called rebar or reinforcing bar, which strengthens the tension component of the concrete. Together, the product is known as reinforced concrete and forms a strong solid foundation to support any tall building. 

Strong Internal Cores

One of the most popular methods for mitigating wind forces is the ability to build strong cores in the center of the building. Usually constructed around the elevators are solid steel and/or concrete trusses, braced by steel beams.

Most of the tall buildings of the 20th century use this method and it is still going strong into the 21st century, but usually, there are more obstacles to the wind added, especially if the building is of the super or mega tall variety.

Corner Softening

Taipei 101 in Tiawan China
Taipei 101 in Taiwan China uses corner softening to dampen the winds

This is a style that softens the edges of tall buildings to reduce the vortices (strong winds) that these structures are subject to.

The 1,667-foot Taipei 101 in Taiwan uses this method which is very effective in controlling high winds.

But that’s not all Taipei 101 uses against wind vortices as we will see below.

 

Setbacks

New York Telephone Building NYC 1926
Lower Manhattan’s NY Telephone Building was one of the first to employ the setback method. Photo: ©Joseph H. Sachs 1926

In 1916, due to the shadow effect that tall buildings would leave on the sidewalks of New York, specifically, the 555-foot tall Equitable Building that was completed a year before, a new zoning law was enacted that would force developers to apply setbacks to all tall buildings.

New York City’s Empire State Building and Chrysler Building are excellent examples of setback design, as well as examples of the esthetic beauty of the art deco structures of that time.

Not only were setbacks desirable but, from an engineering point of view, they helped to diminish the harsh winds that tall buildings were subjected to.

Twisting

Shangai Tower
Shanghai Tower (right). Photo by qi xna on Unsplash

Spiraling skyscrapers are becoming more popular. Not just for their aesthetic appeal, but also because of their ability to reduce wind vortexes by up to 24%.

For the Shangai Tower, this resulted in a reduction of $58 million that the developers did not have to add to buttress the building.

Even more, aesthetically pleasing is the 1,417-foot tall Diamond Tower in Jeddah, Saudi Arabia. If that’s not intriguing enough, there is the 1,273-foot Dubai Tower that not only twists but also rotates 360 degrees. Built by Italian/Israeli architect David Fisher of Dynamic Architecture, the building gives spectators and residents alike an ever-changing view of the Dubai skyline.

Tubular System

Willis Tower Chicago
Willis Tower in Chicago uses a tubular system to mitigate the wind. Photo: ©SMS

The Willis Tower in Chicago is an excellent example of a building that employs the tubular method for addressing wind forces.

This super tall consists of a collection of nine tubes supporting each other, subsequently buttressing the building to fight off the winds more than if it was just one straight up-and-down structure.

Additionally, since they level off at different heights, the wind forces are inherently disrupted.

 

Cutout

A less used method but efficient nonetheless. The wind is allowed to pass through specific areas of a building. which reduces the wind loads on the building. Below is an animation demonstrating how the building negotiates the wind forces using cutouts on various floors.

When employing the cutout wind method, other methods of wind optimization are used along with it.  New York’s 432 Park Ave makes use of this system. Additionally, the building uses the tuned mass damper system as described in the next section.

Tuned Mass Damper (TMD) (AKA harmonic absorber)

Damper illustration for Taipei 101
Tuned Mass Damper illustration for Taipei 101

Large, heavy dampers, usually near the top of the building compensate for building vibrations, such as high winds. Similar to a pendulum that sways back and forth, these dampers will move against the wind thereby stabilizing the building.

In technical terms, the mass damper is designed to work in harmony with the oscillation frequency of the building from the wind, thereby reducing the overall sway of the structure. 

Combination of the Above

Many times, a multiple of these strategies are used to tackle the vortices, and in so doing, they can be very effective in taming the wind. 

Constructing the Superstructure 

The superstructure is the actual building, more specifically, it is the framework that connects the foundation to the roof, and this is where the CAD model is pertinent. The CAD model will help to identify the best location for the support columns, known as the centroid

Engineers will select the most economical material and size of steel for these columns. They must also ensure that the columns are spaced far enough to resist both wind and potential seismic forces. Consideration will go into the type of concrete material and the size of the floor slabs, based on how much weight the slabs must support.

They must also consider the thickness of the slabs based on the amount of deflection allowed by the building codes, but we’ll leave the details of these considerations to another article that provides the specifics of these components.

Structural Engineering in a Nutshell

Watch this video which lays out the concepts of the engineering techniques required to build a tall building.

Summary

The engineering behind the making of skyscrapers is a complex and lengthy journey. When engineers design a supertall, they must consider many different aspects of the project. They must select materials that can withstand the forces of nature such as high winds, heavy precipitation, and even earthquakes.

They must also ensure that the building is structurally sound. In today’s skyscrapers, you can rest assured that the hard work and dedication that was put into each of these buildings by the architects, engineers, and construction workers make these buildings sound and secure. 

 

7 Buildings that Use Cantilever Architecture

Citicorp Tower cantilevers
Citicorp Tower. Photo: Wikimedia CC

In the 19th century, with the advent of structural steel, engineers began using cantilevers to construct taller buildings. This type of architecture is primarily used when there isn’t enough space on one side of a structure for its foundation. Engineers have to build the foundation out from one side and then use beams that extend from it to support the weight. 

This construction style is eye-catching and certainly more daring than other methods of building. It also requires serious engineering skills, as well as a detailed understanding of how much weight the beams can bear without giving way. Indeed, the correct structural engineering is imperative as just a small miscalculation in the production of steel and concrete can result in catastrophe.

‍If you live in a big city, you might have noticed that more buildings are being built with these overhangs. This is especially true for cities where space is at a premium, such as New York City.  In this article, we are going to take office building construction to a whole new level – the use of cantilevers!

The Citicorp Center, New York City

Citicorp Tower looking up
Citicorp Tower, NYC. Photo: Wikimedia CC

​If there was ever a building that emphasized cantilever design it would be the Citicorp Center in midtown Manhattan. Completed in 1977, the 59-story, 915-foot-high skyscraper sits on three stilts with an internal core at the center.

The building is structurally sound now; however, thanks to an observant doctoral student at Princeton University, a discrepancy was discovered when wind forces hit particular angles of the building.

In 1978, Diane Hartley, who was writing a structural engineering thesis, found that the engineer’s calculations did not match hers, which was disturbing since it indicated a possibly dangerous situation.

Should a strong wind ​happen to hit the building’s corners, the possibility of the building toppling over had a chance of collapse. It was a one-in-16 chance, but the danger still existed.

Hartly proceeded to notify William LeMessurier, who was the chief structural engineer. He checked her math and realized she was correct.

Quietly, LeMessurier proceeded to correct the issue. In coordination with the NYP​​D, an evacuation plan was enacted, which covered a ten-block radius. An evacuation almost materialized as a hurricane was forecast to be heading towards NYC. Hurricane Ella was on its way but moved away from the city at the eleventh hour.

Interestingly enough, word did not get out about this until 1995 when it was published in the New Yorker Magazine.

In addition to the skyscraper’s unusual cantilevered design, the developers used their ingenuity to build a large solar panel at the top of the structure; hence, the slanted roof at the top points south. But the idea never materialized, the slanted roof remains as an esthetic addition to the building.

The Rotterdam Tower

De_Rotterdam Tower showing cantilevered construction
Photo: Wikipedia-CC

This intriguing building is located in the Netherlands and is part of the Erasmus Bridge Complex. It is a mixed-use building that houses offices, a hotel, and apartments. The building has a cantilever design, which is why the residents can enjoy a gorgeous view of the river

The architects designed the building so that it extends out over the river and almost touches the bridge. They also designed it so that it is taller on one side. The weight of this building is distributed between its central core and its cantilever, which is why it can be so tall without the ground beneath it being affected.

Statoil Regional and International Offices

Statoil is an energy producer in Norway and the 57th largest company in the world. Norwegian architects A-Lab designed a 117,000-square-meter commercial building complex that fits into the picturesque shoreline of Fornebu in perfect harmony.

Additionally, this architectural expression injects new energy into the nearby park and commercial area and was a key challenge in their design. Of course, it is the overhangs that make the building stand out. They stretch up to 100 feet in many directions.

Marina Bay Sands Hotel

The Marina Bay Sands Hotel is considered one of the most impressive hotels in the world. It is a massive construction project that began in 2003 and was completed in 2011. The project was a collaboration between the Las Vegas Sands Corporation and the Singapore government and was built on the site of a former shipyard. The hotel has three 55-story towers. but in addition to these buildings, it has a sky park that is cantilevered over all three towers.

Designed by Israeli architect Moshe Safdie,  the hotel has 2,500 rooms and a lobby that crosses the entire three buildings just like the sky park above.

Marina Bay Sands Hotel Sinagpore

Marina Bay Sands Hotel by architect Moshe Safdie. Photo by Julien de Salaberry on Unsplash

Building the Hotel

One of the most interesting aspects of the construction of the hotel was that developers used an unusual design that allowed them to build upwards while keeping the foundations stable.

This was necessary because Singapore is located on a floodplain, and it is impossible to build foundations below ground level, so the engineers designed the foundation so that the bottom of the hotel would be constructed on a metal mesh, which would be anchored to the ground. The mesh would keep the foundation stable while allowing sand and water to flow freely through it. The foundation is built in modular sections, which can be raised and lowered as necessary. The builders also used a system of shuttles to transport construction materials to the upper floors of the hotel, as well as the rooftop.

Lessons Learned from MBS’s Construction

As we have seen, the construction of the Marina Bay Sands Hotel was a challenge. It is rare for the ground to shift so dramatically in an area where there is no flooding, and it is even more unusual for builders to build on top of a metal foundation. Although this construction project was unique, it still provided some important lessons for other builders.

The first is that challenges are an inevitable part of construction, and there are always several factors that have to be taken into account. The second is that challenges should not be seen as a reason to abandon the project. When building on the water, the builders of the Marina Bay Sands had to be flexible, and ready to make adjustments at any time. If they had been too rigid, they may not have been able to proceed with the project at all.

One Vanderbilt – New York City

Vanderbilt Office Building under construction
Vanderbilt Office Building under construction. Photo: ©SMS

With space so much at a premium in this city, the only way to build is up, and even then, it might not be enough to encompass the amount of office space that the developers envisioned for the Vanderbilt Tower.

Located across from Grand Central Terminal, it is the fourth tallest building in NYC, rising 1,401 feet above the ground. On the south and west sides, it is cantilevered over Vanderbilt Ave. and 42nd Street respectively, and this overhang starts at only approximately 50 feet up and then supports the rest of the superstructure. There is an observatory at the top, which is the 5th observatory in Manhattan. 

Other skyscrapers with noticeable cantilevered construction in New York include Central Park Tower and the Citicorp Headquarters, displayed above. 

J. P. Morgan Chase Headquarters – New York City

Steel Cantilever at Chase Bank Headquarters
Steel Cantilever at Chase Bank Headquarters Under Construction. Photo: ©SMS
JP Morgan Chase headquarters
JP Morgan Chase headquarters Full View May 21, 2023. Photo: © SMS

Also known as 270 Park Ave., this 1,388-foot-tall, 70-story, 2.5 million-square-foot super tower is located between Park and Madison Avenues, and 47th and 48th Streets.

This massive building will be supported, in part by steel cantilever columns that protrude diagonally out on the eastern and western sides of the building.

Interestingly, the building is replacing the former Union Carbide 52-story tower (later bought by Chase) that was previously there. The building was completely demolished, which made it the largest intentionally demolished building in the world.

The new Chase headquarters will have zero carbon emissions and will be 100% powered by New York hydropower in upstate NY, which produces electricity completely from flowing water.

No doubt, this will be one of New York’s most advanced skyscrapers.

Frank Gehry’s Chiat/Day Building

Binoculars Building, Los Angeles
Binoculars Building, Los Angeles, CA. Photo: Wikimedia CC

This building is a former office building in Los Angeles, California that was converted into a mixed-use building. It is now home to a variety of businesses, as well as the famous advertising agency Chiat/Day.

Designed by notable architect Frank Gehry, this building with a cantilever on one side so that it could house all of the businesses. They designed the cantilever so that it wouldn’t cause damage to the building’s foundations.

The building’s cantilever also allowed designers to create an interesting façade. They were able to extend the second floor out so that it creates a terrace, which is accessible from the sidewalk.

Summing Up

The cantilever is an interesting architectural feature that many people likely do not think about as they walk under these overhangs, but it is a complex engineering solution that isn’t suitable for every project; however, in these examples, it works brilliantly.

While they may be pretty to look at, they also serve a critical function, which makes them a necessity. While the specific structural design of each cantilever will vary depending on the building type, design, and geographic location, the overall concept is the same.