It was designed by the Chicago firm of Skidmore, Owings & Merrill (SOM). Its postmodern form, whose complexity rises as it ascends, draws on traditional Chinese architecture such as the tiered pagoda, gently stepping back to create a rhythmic pattern as it rises. Like the Petronas Towers in Malaysia, the building's proportions revolve around the number 8, associated with prosperity in Chinese culture. The 88 floors (93 if the spire floors are counted) are divided into 16 segments, each of which is 1/8 shorter than the 16-story base. The tower is built around an octagon-shaped concrete shear wall core surrounded by 8 exterior composite supercolumns and 8 exterior steel columns. Three sets of 8 two-story high outrigger trusses connect the columns to the core at six of the floors to provide additional support.