Notes on the Sears Tower Lecture

Introduction

• Sears Tower, tallest building in North America.
• Over 25,000 visitors daily; 104 elevators (some double-decker)
• Stands at 1,450 feet; 110 floors.

Historical Significance

• Tallest building in the world until 1998 (surpassed by Petronas Towers).
• Impressive observation deck with views up to 50 miles (Illinois, Indiana, Wisconsin, and Michigan).
• Over 1 million tourists visit the Sky Deck annually.

Structure and Design

• Skyscraper spans 4.5 million sq ft, equivalent to 5 football fields.
• Unique elevators: fastest at 1,600 ft/min, reaching the 103rd floor in 60 seconds.
• 2,232 steps to the top; 16,100 windows washed by automated rigs.
• Requires 110 janitors, 100 security guards, and various engineers for maintenance.

Elevator System

• 104 elevators, including 14 double-deckers.
• Sky lobbies on the 33rd/34th and 66th/67th floors.

Maintenance

• 50,000 miles of electric wiring; 25,000 miles of plumbing.
• HVAC engineers monitor temperature differences across floors.
• Five chillers provide substantial refrigeration.

Construction History

• Built in 1968 for Sears, which was the dominant retailer post WWII.
• Expanded rapidly due to suburban growth.
• Designed by Skidmore, Owings & Merrill (Bruce Graham and Fazlur Khan).

Construction Techniques

• Used a bundled tube structure allowing for efficient design and numerous floor plans.
• Foundation involved extensive digging and a thick concrete mat.

Challenges During Construction

• Weather delays caused by wind and temperatures below 10°F.
• Construction accidents but no fatalities reported until later in the project.

Completion and Usage

• Completed in 1974, housed 8,000 employees.
• Innovative office spaces with robotic mail carriers.
• For years, occupied 40% of the building, with the rest leased out.

Changes Post-Sears

• Sears moved out in 1990; building became fully leased.
• Renovations included elevator systems and lobby redesigns.
• Security improvements post 9/11 with card access systems.

Legacy

• After various renovations, the building remains iconic.
• Still has the tallest antennas in the world, retaining its title as the tallest building in North America.
• Symbol of Chicago, featured in many images of the city.