Tall Building Models with Various Unconventional Configurations. Aerodynamic Characteristics

Tall buildings have been traditionally designed to be symmetric rectangular, triangular or circular in plan, to avoid excessive seismic-induced torsional vibrations due to eccentricity. However, recent tall building design has been released from the spell of compulsory symmetric shape design, and free-style design is increasing. This is mainly due to architects’ and structural designers’ challenging demands for novel and unconventional expressions.

Development of computer aided analytical techniques and of vibration control techniques using auxiliary devices has also contributed to this trend. Another important aspect is that rather complicated sectional shapes are basically good with regard to aerodynamic properties for crosswind responses, which is a key issue in tall-building windresistant design. For example, changes of corner configurations and variations of sectional shape with height, called aerodynamic modification, make vortex formation and/or vortex shedding weak and/or random, which could improve the wind-resistant performance of tall buildings.

The effectiveness of aerodynamic modification to reduce wind loads has been widely reported, and aerodynamic modifications thought to be effective can be classified as modifications of sectional shape (horizontally) such as polygon or Y-type (Hayashida et al., 1992), corner modification {Miyashita et al., 1993; Amano, 1995; Kawai, 1998), modifications of building shape (vertically) such as taper (Cooper et al, 1997; Kim et al., 2008; Kim and Kanda, 2010a, 2010b) or setback (Kim and Kanda, 2010a, 2010b), and introduction of openings (Miyashita et al., 1993). Although there are some reports on cross comparisons between different aerodynamic modifications using a limited number of aerodynamic modifications, almost none have comprehensively investigated the aerodynamic characteristics of various types of tall buildings with different configurations.

To investigate the relationships among structural properties, aerodynamic modifications and aerodynamic force characteristics, aerodynamic force measurements and wind pressure measurements were conducted on models with various aerodynamics modifications, and related response analyses were also conducted. This paper discusses the results of aerodynamic force measurements and wind pressure measurements for models that showed effective wind-resistant performance.

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Materials is courtesy of CTBUH
Text: Y. Tamura, Tokyo Polytechnic University;
Y.C. Kim, Tokyo Polytechnic University;
H. Tanaka, Takenaka Corporation;
K. Ohtake, Takenaka Corporation;
M. Nakai, Takenaka Corporation