Influence of opening rate and opening position on wind load and aerodynamic stability of long-span truss roof structure

Long-span truss roof structures are significantly susceptible to wind loads due to their inherent properties of being lightweight, small stiffness, and exhibiting high flexibility. The objective of this study is to evaluate the wind-induced response of a long-span truss roof structure under both closed and different open working states. This will be achieved through the utilization of pressure measurement wind-tunnel tests, finite element modelling, and dynamic response analysis. The present study conducts a statistical analysis on the influence of opening rate and opening position on wind load characteristics and wind response. The Welch method and Frequency method are employed to investigate the spectral characteristics of fluctuating wind pressure and the spatial correlation evolution of wind pressure in the low-frequency range. The findings indicate that the introduction of ventilation openings leads to a notable reduction in mean wind load. The presence of these openings, however, leads to an increase in localized wind pressure fluctuations due to the generated prominent turbulence. Secondly, the friction generated during the opening process primarily dissipates low-frequency large-scale vortex energy, thereby leading to a higher frequency distribution of fluctuating wind pressure spectrum. The time-averaged wind response, fluctuating wind response, dynamic response spectrum characteristics, and probability density distribution characteristics of the roof structure are statistically analyzed based on this premise. The results indicate that the variation in wind-induced response of the roof structure aligns with the fluctuation in wind load as a function of opening rate. When the frequency is lower than the dominant frequency, opening ventilation mitigates wind-induced vibration response of the structure; conversely, opening ventilation will amplify wind-induced vibration response of the structure. The windward area of the long-span truss roof structure experiences buffeting. The structural aerodynamic instability occurs in both the rooftop and wake region due to the presence of non-Gaussian, non-self-excited aerodynamic forces and modal vibrations.