James von Klemperer
Kohn Pedersen Fox Associates, New York City
Roles of Twin-Tower Linkages in Structural Optimization Design for Wind Effects
Steve Zuo1, Aamer Islam2, Jiming Xie3
Twin-tower linkages, such as skybridges or skygardens, provide extra accesses between tall buildings and can thus play favorable roles in improving transportation and communication in urban environment.
Although extensive researches on wind-induced responses of supertall buildings have been published in the past, only limited studies on linked supertalls can be found in literature due to great complexity of the problem. As a result, conventional design for linked towers often takes overly conservative approaches.
Current researches indicate that characteristics of wind forces on twin towers can be quite different from those on a single tower. In most engineering cases, the wind forces on twin towers tend to be strongly correlated in out-phase, so that the design of linkages can have a great impact on the overall structural responses. With adequately designed linkages, the common issues of across-wind response for super-tall buildings can become much less significant and the design wind loads on the linked twin-towers can be considerably smaller than simply double of the single tower wind loads.
Aerodynamic characteristics of twin towers demonstrate how the wind loads are distribution and the spacing between the towers affects the correlation of wind forces in terms of magnitudes and phase angles. The study shows the possible roles linkages can play in structural optimization for wind effects.
The proposed Twin Tower World Trade Center located in Phnom Penh, Cambodia, is taken as case study. It is verified that by structural linkages, the overall structural wind loads can be reduced to about 75% of the two single tower wind loads added together.