Outrigger Systems for Tall Buildings

Goman Wai-Ming Ho
Arup, Hong Kong

The structural efficiency of tall buildings heavily depends on lateral stiffness and resistance capacity. Among structural systems for tall buildings, outriggers are one of the most common, especially for those buildings with a relatively regular floor plan. The use of outriggers in building structures can be traced back from the early 1950s, from the concept of “deep beams”. With increasing building height, deep beams have become concrete walls or at least one-story-high steel trusses. Because of the widened choice in material that can be used in outriggers, the form and even the objective of using outriggers has also changed. The design and construction issues of outriggers cannot be separated. The axial shortening effect between core and perimeter structures is unavoidable. This presentation illustrated a state-of-the-art review of outrigger systems in tall buildings, including development and applicatyion history. The concepts of outrigger system, optimum topology, damped outrigger system, and design and construction considerations were also discussed and presented.