In the past, to investigate aerodynamic characteristics of a train under a natural wind, a full-scale model test was performed, and wind velocities and aerodynamic forces acting on the vehicle models were measured. The values of aerodynamic coefficients calculated from these data were scattered widely but the causes of scattering have not been made clear. In this study, we discussed the influence of wind fluctuation on the scattering of side force coefficients. Both wind fluctuation and side force fluctuation are modeled using statistical models, and then the side force coefficients are calculated by these statistical models. Comparing the calculated results with the experimental results, we found out that side force coefficient ratios obtained from these models are in good agreement with those obtained from experiment results.
Recently, rooftop signboards are often damaged and blown off by strong winds. Flying debris resulting from the damage to signboards may cause second damage to other buildings and people. To prevent such damage, an appropriate wind-resistant design should be done to the signboards. In practice, however, wind force coefficients for rooftop signboards are not provided in the codes and standards in Japan. The present paper investigates the characteristics of wind forces acting on the signboards installed on the rooftop of low-rise and middle-rise buildings on the basis of a wind tunnel experiment, in which the shape, size and location of the signboard are varied over a wide range. Special attention is paid to the time-space correlation of net wind forces acting on the signboard. Based on the distribution of peak wind force coefficients, the signboard is divided into several zones, for which the wind force coefficients are specified. The proposed wind force coefficients shall be used for designing the cladding and components of signboards.