Concrete Core Braced System for Ultra-Tall Buildings

Concrete walls around cores have been frequently used to provide wind and seismic resistance for tall buildings either in concrete or in mixed systems with steel framing. The concrete core braced system has offered great opportunities for shaping of the exterior of the building and appears well suited for emerging design trends. These trends demand diversity in exterior shaping involving plan and profile variations to fit the site constraints or relate to various expressions of aesthetics involving bays, offsets and other facade variations. In all these cases, the simpler non-rigid steel frame can be used which can readily adapt to these variations. An example of an interacting core-frame system relates to the proposed 85-story Dearborn Center building in Chicago.