Sears Willis Tower Chicago

Sears Tower Chicago also known as Willis Tower Chicago marked ”skyscrapers era” in USA and for 20 years it was the tallest building in the world. It is 443 metres high, with 110 floors ground floor, and it is located in the centre of Chicago, Illinois, USA. That tower was built in 1973 for Sears, Roebuck and Company, a company with 7 000 employees so that all of them could fit under one roof.

The Sears Tower Chicago is first skyscraper made with brand new technology, at that time, and much taller than the other buildings. Because of its height, that skyscraper must be flexible in strong winds yet rigid enough to prevent large sideways movement.

Key information about Willis Tower

Category	Details
Name	Willis Tower (formerly Sears Tower)
Location	233 South Wacker Drive, Chicago, Illinois, United States
Coordinates	41°52′44″N 87°38′09″W
Status	Completed
Type	Commercial (Office)
Height	1,450 ft (442 m)
Height with Antenna	1,729 ft (527 m)
Floor Count	110
Floor Area	4.56 million sq ft (424,000 m²)
Construction Started	1970
Completion Year	1973
Architect	Bruce Graham (Skidmore, Owings & Merrill)
Structural Engineer	Fazlur Rahman Khan
Developer	Sears, Roebuck & Co.
Main Contractor	Morse Diesel International
Design Features	Bundled tube structural system; black aluminum and bronze-tinted glass exterior
Notable Facts	– Tallest building in the world from 1973 to 1998
	– Second-tallest building in the United States (after One World Trade Center)
Skydeck	Located on the 103rd floor with “The Ledge” glass balconies extending 4.3 feet (1.3 meters) outward
LEED Certification	LEED Gold Certification for sustainability
Ownership	Owned by Blackstone Group
Tourist Attraction	Over 1.7 million visitors annually

Source: Wikipedia

Design

Ground floor of Sears Tower Chicago is made of 9 square pipes with side 22,9 metres long and different heights. Two of them are reaching the 50th floor, two reaching 66th, three 90th and the last ones are going all the way to the top. That solution makes the building visually thinner and more elegant. Even the floors have areas between 3 800 and 1 100 m2.

Construction

In every square there are 4,6 metres spaced steel columns. Columns and beams were made out of steel tin welded in W profile. Thickness is 100 mm in the bottom, where the load is the biggest, an only 25 mm at the top. Steel construction was made on concrete slab 1,5 m thick and the pylons. Pylons are concrete with steel reinforcement. Their diameter is 2,2 – 3 metres and they are 20 metres deep in the ground. Steel skeleton is prefabricated in dimensions 7,6 x 4,6 metres.

Elevators

Sears Tower Chicago has 102 elevators for employees, vertically it’s divided in 3 parts with 30 or 40 floors. In every part, at the bottom, there is ”sky lobby”. About 16 500 people can come to sky lobby with 14 fast elevators, and then there are local elevators which are taking them to their rooms. On 102 floor, there is public viewpoint. From ground floor to viewpoint you can come with elevators with speed around 30 km/h.

Interior

The Property’s amazing three-story lobby embraces visitors with sculptor Alexander Calder’s Universe, that is a mobile of various shapes, colors and movements. It is demonstrating the limitless potential of human imagination. Sears Tower lobbies are modernistic, with transparent walls and escalators piercing the vertical space. The lobby is characterized by polished granite flooring and travertine walls with stainless steel column covers. The main lobby of Sears Tower Chicago consists of one entry on the east side of the building and one entry on the west side of the building. The Wacker Drive lobby acts as the main entrance to the Property offering access from the street. The east entrance is accessed directly from Frankin Street.

Exterior

The architect and structural engineer created the Tower’s curtain wall of glass and aluminum. The curtain wall system is made of bronze-tinted vision glass and black anodized aluminum spandrels panels. Granite panels, with aluminum-framed glass hold front windows, highlight the ground level façade on the east, north and south building elevations. Building setbacks are presented on the building’s northwest and southeast corners at the 50th floor, the northeast and southwest corners at the 66th floor, and the north, south and east elevations on the 90th floor. The structural framing is composed of steel columns and beams containing nine modules. The foundation system consists of belled, reinforced concrete caissons with reinforced caisson caps. The Franklin Street entrance has a stunning large glass, aluminum and steel cover which was additional to the Property in the middle of the 1990’s.

Fire safety

Sears Tower Chicago has one of the best life protection systems for building in the world. All steel is fireproofed, programmed sprinklers cover each of the 4.5 million square feet of space. Smoke detectors are developed to discover the source of the smoke and at some point will exhaust the smoke from impacted areas. The self-contained support emergency power supply supports the alarm system, fire pumps, communication system, emergency lighting and select elevators in the occasion of an electrical malfunction. There are four two-hour, fire-rated stairwells, one of which is specifically aired for smoke-free evacuation.

Fire Sprinklers

The building is protected all through by automatic sprinklers. The Lower Level South and North Loading Docks, Level 1A parking garage and Sky Deck entry are protected by sprinkler devices. There are a total of three water tanks in the building. The water tanks can be supplied with water from the fire pumps in the areas beneath the tanks. One water tank has a 10,000-gallon capacity and two are 5,000-gallon capacity. These tanks function as a main water supply to the building fire pumps.

Sears  Tower Chicago becomes Willis Tower Chicago

Changing the name of the tower which is already worldwide know by Sears Tower Chicago? It’s all a part of a bargain with the London-based Willis Group Holdings. They relocated 500 employees into 140,000 square feet on multiple floors of the 110-story building, so the Willis Group gets the naming privileges as part of it’s lease agreement with the real estate investment group that is the owner of Sears Tower Chicago. It all took place in 2011.

Willis Tower Chicago in numbers

• Height: 443 metres, with antenna 520 metres

• Ground floor: 409 000 m2

• Weight: 222 500 tonnes

• Hired workers: 16 500

• Price: 150 million US dollars

FAQ

1. What is the Willis Tower?
   • The Willis Tower, formerly known as the Sears Tower, is a 110-story skyscraper in Chicago, Illinois, and was once the tallest building in the world.
2. When was the Willis Tower built?
   • Construction began in 1970 and was completed in 1974.
3. How tall is the Willis Tower?
   • The architectural height of the Willis Tower is 1,451 feet (442 meters), with a tip height of 1,729 feet (527 meters).
4. What can visitors do at the Willis Tower?
   • Visitors can access the Skydeck on the 103rd floor, which features stunning views of Chicago and The Ledge, a glass-bottom balcony.
5. How many visitors does the Skydeck attract each year?
   • The Skydeck attracts approximately 1.7 million visitors annually.
6. Is the Willis Tower open to the public?
   • Yes, the Skydeck is open to the public, but it’s advisable to check for any restrictions or hours of operation before visiting.
7. How do I get to the Willis Tower?
   • The Willis Tower is located in downtown Chicago and is accessible via public transportation, including buses and trains, as well as by car.
8. What is the history behind the name change from Sears Tower to Willis Tower?
   • The building was renamed in 2009 after the London-based insurance broker Willis Group Holdings acquired naming rights as part of their lease agreement.
9. Can you see other states from the Skydeck?
   • Yes, on clear days, visitors can see parts of Indiana, Wisconsin, and Michigan from the Skydeck.
10. Are there any restaurants or shops in the Willis Tower?
    • Yes, the tower features various dining options and retail spaces, especially after recent renovations.

Wrapping Up

The Willis Tower, with its rich history, innovative design, and cultural significance, stands as a testament to Chicago’s architectural legacy. Whether you’re admiring the city from the Skydeck or marveling at its engineering brilliance, the Willis Tower remains an iconic destination for tourists and locals alike.