Sears tower

sears tower

1. Sears Tower ( Willis Tower)

2. Sears Tower • Location: Chicago, Illinois Project started: 1970 • Project Completion: 1974 • Site Area: 3 acres • Project Area: 4,565,844 ft2 (105 acres) • Number of Stories: 110 • Building Height: 1,450 ft (442 m) • Market: Commercial + Office 3.8 million rentable square feet (89 acres) • retail space. (0.36 acres) • 160-car executive parking garage. second-tallest building in the United States

3. TIP ARCHITECTURAL TOP FLOOR

4. The Ledge at Skydeck Chicago at 103 floor

5. Forces and Form • The Willis Tower draws its strength, both visual and physical, from its structural form, the bundled tube. • The building plan consists of 9 squares, each 75 feet across, placed in a three by-three grid arrangement. • Each square has 5 columns per side spaced 15 feet on centers, with adjacent squares sharing columns. • As the columns rise up the building, each square in the plan forms a tube, which can be seen on the exterior of the building. • These tubes are independently strong but are further strengthened by the interactions between each other through truss connections. • While the tubes connect at each floor level with beams and floors trusses, several large trussed levels act as the main horizontal connectors in the buildings

6. Construction The closely spaced interior and exterior columns are tied at each floor with deep spandrel beams. At the truss levels, these tubes are tied together. • These ties resulted in a stiffer structure, as the building acts as a unified system of stiffened tubes. • The interaction between the individual tubes and the belt trusses at mechanical levels allows the building to attain its extreme height. • Due to the drop offs, the gravity loading on the system is not evenly distributed along the height of the building. • These trusses take the gravity loads from above and redistribute them evenly onto the tubes below. • This is particularly important for the uppermost section of the tower, due to its asymmetry about the central axis of the building. • The presence of the belt trusses help to mitigate these effects of differential settlement, which cause the building to tilt.

7. Vertical Circulation • The Sears Tower’s 104-cab elevator system divides the building into three separate zones, with sky lobbies in between at levels 33-34 and 66-67. • 28 double decker express shuttle shuttle elevators serve the sky lobbies • 63 single deck elevators for intra- zonal travel • 6 freight elevators • Two express elevators that take 61 seconds to reach the 1353 foot high skydeck at level 103 travelling at 1600 feet per minute.

8. 38th Floor Plan Service lifts Lifts/elevator staircase washrooms

9. 48th Floor Plan washrooms staircase Lifts/elevator Service lifts

10. 85th Floor Plan staircase Service lifts washrooms Lifts/elevator

11. 95th Floor Plan washrooms Lifts/elevator staircase Service lifts