Response characteristics of super-tall buildings – Effects of number of sides and helical angle

• The effects of increasing number of sides and helical shapes on responses were investigated.
• The largest overturning moments were found for the straight triangular model.
• The largest spectral values, hence responses, were found for the straight square model.
• Differences in peak accelerations become small when the number of sides is larger than 5.
• The effects of helical shape becomes small when the number of sides is larger than 5.

Wind tunnel tests were conducted on 13 straight and helical super-tall buildings with various polygonal cross-sections, including triangular, square, pentagon, hexagon, octagon, dodecagon, and circular. The primary purpose of the present study was to investigate the effects of increasing number of sides on response characteristics rather than other aerodynamic characteristics for straight super-tall buildings and the effect of helical shape on polygonal section super-tall buildings. The results show that the overturning moment coefficients, the spectral values and responses decrease with increasing number of sides, and the largest mean and fluctuating overturning moments were found for the straight triangular model and the largest spectral values and responses were found for the straight square model. The largest peak accelerations for annual design wind speed were similar when the number of sides were larger than 5, but some variations were observed in the largest maximum displacements among models. The effects of helical shape on the response characteristics decreased with increasing number of sides, and it can be generally said that the effect of helical shape becomes small when the number of sides is 5 or more.