Completed in 1974, Willis Tower set the standard for supertall skyscrapers around the globe, both in its innovative design and graceful styling. The Willis Tower (formerly Sears Tower) in Chicago, with its signature black aluminum and bronze-tinted glare-reducing glass, was the tallest building in the world for nearly 25 years. Within a composite building’s primary structural elements. Where known, the CTBUH database breaks out the materials used Examples include buildings which utilize: steel columns with a floor system of reinforcedĬoncrete beams a steel frame system with a concrete core concrete-encased steel columns Ĭoncrete-filled steel tubes etc. steel, concrete, timber) are used together in the main structuralĮlements. ForĮxample, a Steel Over Concrete indicates an all-steel structural system located on top of anĪll-concrete structural system, with the opposite true of Concrete Over Steel.Ī combination of materials (e.g.

all-steel, all-concrete, all-timber), one on top of the other. Or concrete slab on top of timber beams is still considered an “all-timber” structure as theĬoncrete elements are not acting as the primary structure. Note that a building of timber construction with a floor system of concrete planks

An all-timber structure may include the use of localized non-timber connections between Reinforced concrete which has been precast as individual components and assembled togetherįrom timber. Note that a building of steel construction with a floor system of concrete planks orĬoncrete slab on top of steel beams is still considered an “all-steel” structure as the concreteĮlements are not acting as the primary structure.įrom concrete which has been cast in place and utilizes steel reinforcement bars and/or steel Both the main vertical/lateral structural elements and the floor spanning systems are constructedįrom steel.

Willis tower tour