Evaluation of aerodynamic instability for building using fluid–structure interaction analysis combined with multi-degree-of-freedom structure model and large-eddy simulation

To evaluate the aerodynamic instability for buildings considering their high-order oscillation mode and torsional oscillation mode on which it is difficult to perform the usual wind tunnel experiments, the fluid–structure interaction (FSI) analysis code combined with a multi-degree-of-freedom structure model and large-eddy simulation was developed. The calculation results obtained in this study and the results of wind tunnel tests conducted in a previous study using a building model (average breadth 0.14 ​m ​× ​length 0.28 ​m ​× ​height 1 ​m; scale: 1/600) with a multi-degree-of-freedom structure were compared. The comparison showed that the FSI analysis results were corresponded well with those of the wind tunnel tests; for each spectrum of response displacement (wind, along-wind, and torsional direction) at the top mass node, the frequency distribution and the peak frequency of the first and second oscillation modes were in good agreement with the calculation results and the wind tunnel test results. As for the amplitude of the top displacement of the building, the results for both the along- and across-wind directions showed good correspondence. For the torsional direction, the calculation results reproduced a torsional flutter oscillation with a slightly low wind level in comparison with that observed in the wind tunnel experiments.