Following his graduation at the University of Pennsylvania in 1948 with his degree in Architecture, Architect Bruce Graham worked for Holabird and Root (1948-1951) and SOM (1951-1991). During his 40 year tenure at SOM, Graham designed notable buildings all over the world, including the Inland Steel Building (1957), DeWitt-Chestnut Building (1995), and John Hancock Center (1974). Show pictures of buildings

Approached by Sears Roebuck & Co. in the 1960s to build their new headquarters in Chicago’s West Loop, Graham partnered again with SOM’s Engineer Fazlur Kahn (previous relationship began with Hancock Center) to design Sear’s new tower, with an emphasis on cost efficiency. Kahn studied at the University of Illinois, Ubrana earning a masters degree and Ph.D in civil en-gineering and a masters degree in theoretical and applied me-chanics. The Sears team consisted of Architect Bruce Graham, Structural Engineer – Fazlur Kahn, Engineering Team Lead – Hal Iwengar, and Sears Roebuck & Co. commissioned Environetics- a firm specializing in computer based drafting focused on cor-porate interior design.

Grahman and Kahn’s design processes were both deeply rooted in the structural system, both positioning themselves on the no-tion that “Only when architectural design is grounded in struc-tural realities can the resulting aesthetics have a transcendental value and quality.”

THE SEARS TOWER1973

DeWitt-Chestnut Building (1995) InLand Steel Building (1957) John Hancock Center (1974)

Bruce Graham Fazlur Kahn + Bruce Graham

Fazlur Khan revolutionized the construction of high-rise towers through the advance in structural design, he is often regarded as the “Father of Tubular Designs for skyscrapers” When commis-sioned to work on the Sears Tower, Khan developed the bundled tube system, an evolution of the tubular system. The evolution was to divide a large tube into smaller units which then creates a series of smaller framed tube “bundled” together to create a large bundled tube structure. This new structure maximized the lateral sway resistance due to the cantilever behavior or column shortening and it minimizes the shear wracking compo-nent caused by bending deformations of the columns and frame beams of the tube. The bundled tube formation resulted in a highly efficient tubular structure for a large floor plan building – directly aligning with the building goals of Sears Roebuck & Co.

The modular framed tube units called “Christmas trees” were transported to the site, one per truck, erected by cranes and field bolted to adjacent units. The elimination of almost all field welding and the incorporation of simpler field bolted joints re-sulted in a substantial fabrication economy. Due to the enor-mous size and complexity of the project, it was critical that the schedule be compressed or fast-tracked in order to reduce the length of construction time. Preliminary design started by SOM in 1969, groundbreaking and the beginning of site excava-tion was in August, 1970, caisson construction began in Janu-ary 1971, structural steel was issued in packages beginning in September 1970. The first structural steel was erected in June 1971 and the steel was topped out in May 1973. This fast track schedule applied to all trades involved in construction resulted in the first Sears employees occupying the lower 28 floors of the building in September of 1973. The remainder of the building was completed in March, 1974.

During the planning and design of the building, Sears was faced with a major decision regarding the fire safety provisions being designed into the building. Fire sprinklers were being more and more recognized for their ability to suppress and control fires in high-rise buildings but were not yet required by code. Eventu-ally, Sears made the decision to provide sprinklers throughout the entire area of the building. This decision made Sears Tower the first large, commercial high-rise building to be 100% sprin-klered, representing a technical mastery for its time.

Belt Truss for One Tube

Air Circulation + Application of StructuralModule - Aaron Ausing

Sears Tower Bundled Tube Construction - Aaron Ausing

Sears Tower Construction Photos Structural Module “Christmas Tree” - Mike Mettee

AIR CIRCULATION

Sears Roebuck & Co. were not intending on building an archi-tectural monument. They wanted a building designed and built on the ideologies of economy and efficiency. A tipping point during construction of the Sears Tower arrived when the world’s tallest building title was within reach. Completing construction in 1970, the World Trade Center Towers were to hold the title at 1,368 feet. SOM and Sears both decided that the economi-cal and efficient bundled tube structure should be taken to the limits at 1,450 ft to surpass the World Trade Center Towers and appropriate the title.

Sears was known for being a mail order modular, selling any-thing from a fitted shirt to a house through a catalog. Their busi-ness model was built around efficiency and economy, the Sears Tower building represents this model from the manufacturing of the truck-sized “Christmas tree” units to the 2 floor construction per week timeline. The interior design of the Sears Tower was approached with the same business model philosophy. Commis-sioning digital technology of the firm Environetics, a trailblazing firm with a then-new concept of focusing on corporate interi-or design and utilizing computer drafting systems to optimize space through determining appropriate square footage needs of each employee based on position within the company and studying the daily circulation habits. The Sears Tower worked as machine from construction to inhabitation, just as Sears Roe-buck & Co. had intended. Today the Sears Tower, now known as the Willis Tower, still serves as popular destination for tourists and alike, as it has had the ability to withstand the times and continues to reinvent itself.

Ali, Mir M. Art of the Skyscraper: The Genius of Fazlur Khan. New York: Rizzoli, 2001. Print.

Diemer, Lauren. Sears Tower: Structural Wonders. New York, NY: Weigl, 2010. Print.

Pridmore, Jay. Sears Tower: A Building from the Chicago Archi-tecture Foundation. San Francisco: Pomegranate, 2002. Print.

Typical Floor Plan 2

Typical Sky Lobby Typical Floor Plan 1Typical Base Floor Plan-Chelsey Schon

Diagram Model of Elevator Serviced Floors-Jesse Campos

25,000 people enter the Willis Tower every day. 1,000,000 people visit the sky deck annually. The circulation system of breaks down as follows:-30 express elevators-6 freight elevators-12 banks of elevators total : 64 elevators Bank 1: 6 elevators : 4-10 Bank 2: 6 elevators : 10-17 Bank 3: 6 elevators : 17-23 Bank 4: 6 elevators : 23-28 Sky Lobby Bank 5: 6 elevators : 34-42 Bank 6: 6 elevators : 42-49 Bank 7: 6 elevators : 49-57 Bank 8 : 6 elevators : 58-63 Sky Lobby Bank 9 : 4 elevators : 68-74 Bank 10 : 4 elevators : 75-81 Bank 11: 4 elevators : 82-87 Bank 12 : 4 elevators : 90-102

Double Deck Express Elevators Lobby & Mezzanine

Elevator Bank A

Elevator

Elevator Control

Elevator Machine

Structure

Electrical

Call ButtonSky Lobby Floors 33, 34, 66, &67

Elevator Bank B

Vertical Circulation Transfer Diagram Integrated Elevator Operation

FIREPROOFING

FIRE BREAK

ALUMINUM CURTAIN WALL

W SHAPE

INTERIOR COLUMN FINISH

THE INTERIOR COLUMN FINISH INTEGRATES WITH THE EXTERIOR CURTAIN WALL SYSTEM ALLOWING FOR A MOMENT OF MIESIAN EXPRESSION.

ALUMINUM SPANDREL PANEL

FIREPROOFING

RADIANT HEAT PANEL

HYDRONIC SUPPLY

MODULAR STRUCTURAL UNIT

ALUMINUM CURTAIN WALL

FACTORY PUNCHED OPENING

FACTORY PUNCHED OPENINGS IN THE STRUCTURAL STEEL ALLOWED FOR INTEGRATION OF THE BUILDING’S HVAC AND HYDRONIC HEATING ADJACENT TO THE FLOOR JOISTS.

SHEAR STUDS

CONCRETE TOPPING

METAL DECKING

W SHAPE BEAM

ELECTRICAL SERVICE

THE CORRUGATED METAL PAN FLOOR DECKING CREATES A NATURAL CHASE THAT ALLOWS THE ELECTRICAL WIRING TO BE INTEGRATED INTO THE FLOOR ASSEMBLY.

EXIT STAIR

EXIT STAIR EMERGENCYSIGN

DOOR ACCESS

CORE

EMERGENCY SIGN AND CIRCUIT CONNECTIONS

PANIC BAR

EXIT SIGN

STROBE

EMERGENCY DOOR

EXIT

Jesse Campos Chelsey Schon

Mike Mettee

AIR CIRCULATION

CONCRETE TOPPING

METAL DECKING

SOME CHASES LEFT OPEN FOR FUTURE TECHNOLOGY

120V ELECTRICITY

TELEPHONE CABLE

FLOOR TRUSSCONCRETE TOPPING

METAL DECKING

TREE MODULE

SHARED COLUMN BETWEEN TUBES

At the building scale integration is happening at the belt trusses. The increase in structure at the levels makes them unfit for occupancy as there would be little exposure to natural light and the views are blocked. Instead, these levels are strictly mechanical. The structure dictates the program (mechanical) while also serving as the lateral bracing for the entire building and redistributing gravity loads evenly to the tubes below.

Zooming in, the tree modules each have a 19” diameter circle cut out of the web of the beams on either side of the column. These allow for the mechanical systems (such as air ventilation) to run between tubes. The open web floor trusses (which carry less load than the beams on the exterior of the tubes) allow this as well. Here, the mechanical systems are tightly woven into the structure of the building in the 42” plenum space that occurs at each floor.

A closer look at the floor reveals further integration of systems into the structure. The metal decking that the concrete topping sits on leaves chase spaces. These spaces are above the larger plenum space where water and air circulation takes place. Here, electricty and telephone cables are run. Also, Sears was well aware of the increasingly changing technology and left many of these chase spaces open. They are labelled on drawings as “future tech.”. This has allowed the building to enter the 21st century with fiber optic cables and other high speed computer equipment cables almost seamlessly.

Aaron Ausing