A strong wind would cause roof openings on a low-rise building and bring further structural damage. Previous related studies focused on different shapes of openings on flat roofs. Little study has been done on the sloped roofs with openings in vulnerable roof areas. In this study, wind tunnel tests were carried out to investigate the steady-state and transient internal pressure characteristics due to opening at the vulnerable roof areas of a low-rise building. The tests considered both steady-state and transient openings of roof. The experimental results indicated that the steady-state internal pressure distribution tends to be uniform and that the internal pressure induced by leeward roof ridge opening is obviously lower than that induced by the windward one. The fluctuation effect around the orifice area is apparent with the skewed wind direction and the combined effect of internal and external pressures on the unopened roof side is significantly smaller than that on the opened side. Current design provision of China for internal pressure evaluation is found to be unconservative. The transient overshoot is closely related to the opening location in the vulnerable roof area and is more pronounced when the opening is on the leeward side. Among the internal pressure coefficients commonly adopted in design, the extreme net wind pressure coefficient is most important, which is affected most at the orifice near eaves, roof corners and tails, and leeward roof ridge.

To meet the ventilation requirement, an engineer needs to design the cantilevered roof of a stadium as a layered one with gaps between the layers. In order to further understand the wind resistance performance of such structures, a wind tunnel test was carried out on a 1:200 scaled stadium model considering two roof inter-layer cases: opened gaps and blocked gaps. The laws of lift force coefficients and net wind pressure coefficients were compared for these two gap conditions. The study results indicate that the roof experiences larger mean lift force on both top and bottom surfaces when the inter-layer gaps are blocked. However, the roof gaps can reduce the fluctuating lift force on top roof surface and the net fluctuating lift force, weakening the vibration of the flexible large-span roof. The negative pressures (suctions) in the inner and middle roof areas on the leeward side decrease for the blocked gap case. The positive pressure in the outer roof area generally increases along the windward direction, while the negative pressure decreases in other wind directions, when the roof inter-layer gaps are blocked. In the highest and transition roof areas, the fluctuating pressures increase for most wind directions, while in the lowest roof area, they decrease when the roof inter-layer gaps are blocked. The test and analysis results provide a valuable basis for the wind design of this kind of roof structures.

The vortex shedding phenomenon caused by flow separation at windward corners of a high-rise building would lead to significant vortex-induced vibrations (VIVs). This paper proposes a novel and efficient two-way coupled fluid-structure interaction (FSI) method named as equivalent lumped mass system (ELMS) method to study the wind-induced responses of the Common Advisory Aeronautical Council (CAARC) building. The numerical results of ELMS are validated based on available data of aeroelastic tests. To verify the computational efficiency of ELMS method, this study also employs the other two two-way coupled FSI methods (free-form deformation (FFD) method and mapping interpolation algorithms in system coupling (MIASC) method) to simulate the response of the same high-rise building. Furthermore, the VIV mechanisms of the high-rise building are explicitly discussed based on the numerical results of the ELMS method combined with large eddy simulation (LES). The outcomes show that the ELMS method could well capture the significant amplification of cross-wind response and “lock-in” phenomenon at the range of the critical wind speed. Moreover, the computational efficiency of the ELMS method is much improved compared with the other two FSI methods. The spatial correlation and spectral coherence of the local loads at different heights of the building are increased significantly at the “lock-in” stage. The findings in this study would facility the comprehensive understanding of the VIV phenomena of the high-rise building and provide an efficient two-way coupled FSI method for engineers and researchers involved in the wind-resistant design of slender tall buildings.

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