In this study, the characteristics of aerodynamic responses and the steady pressure distributions on the three circular cylinders in an equilateral-triangular arrangement were investigated by wind tunnel tests. The responses of three circular cylinders for various incidence angle α and spacing ratio S/D show more severe aerodynamic instadileties than those of two circular cylinders, especially the aerodynamic instability of downstream cylinder is remarkable. The “wake galloping” occurs as a different vibration mode in case of three cylinders and peculiar aerodynamic behaviors that have not occurred on two cylinders arises . As for the profiles of pressure distribution, the most complex feature can be found on the cylinder located in downstream. The profiles of pressure on downstream cylider varied through a certain procedure according to the increasing α for all S/D tested. By the results obtained, it can be observed that there is a close relation between the characteristics of aerodynamic responses and the profiles of steady pressure distribution on the three circular cylinders.

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Wind-induced internal pressures in buildings were analytically evaluated by using external pressure coefficients of six typical building models. The overall building porosity and the specific wall openings were taken into consideration in the evaluation. The analytical approach was based on the balance of flow through the openings. The evaluation results show that the mean internal pressure coefficients are the values ranging from -0.4 to 0.0 for the all walls equally permeable buildings. For the non-equally permeable buildings, the relations between the mean internal pressure coefficient and the opening ratio are shown in this paper.

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