Question

A bundled tube structural system was used in which of the following Chicago buildings:
A. John Hancock Tower
B. First National Bank
C. Sears Tower

Answer

In 1976, the Sears Tower (recently renamed Willis Tower) was built with a structural system consisting of nine large vertical "tubes" bundled together, forming a single composite column that is cantilevered from its foundation. Each tube has lateral resisting ability on its perimeter, and the tubes gain additional lateral strength when bundled together.