Investigation of the elliptical resonant vibration of high-rise buildings induced by the oblique-downwind interference effects

The interference effect is one of the difficult topics in wind engineering research themes. Enormous publications have been made to understand its whole picture qualitatively and quantitatively in the past several decades. However, rare results focused on the interference effects of the neighboring building located downstream. This study intends to investigate several mentioned downstream interference effects based on the high-frequency-force-balance tests. Four different cross-sections are selected to understand how the adjacent building's appearance interferes with the square principal building. Results show that the interference effects induced by the downstream neighboring buildings can be categorized into two locations - the oblique-downwind location and the downwind location. The oblique-downwind interference effect generates two different motion shapes of the principal building, including the inclined hollow elliptical motion from the two-directional resonant vibration and the standing elliptical motion from the one-directional resonance. The downwind interference effect generates a similar one-directional resonance. Several force spectrum examples are given in this study to illustrate how the oblique-downwind interference effect mechanism forms at a specific distance and reduced velocity. In addition, the results from the augmented experiment with more combinations of two buildings suggest more efforts are necessary for inspiring the phenomenon of an inclined hollow elliptical motion.