• Journal of Korean Association for Spatial Structures
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• v.18 no.2
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• pp.79-86
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• 2018

Unlike other types of outdoor advertisements, rooftop signboards are installed on the roofs of buildings, rather than on their outer walls. This means that the area of a rooftop signboard is commonly larger than that of a general outdoor signboard. Moreover, as such signboards are greatly influenced by the wind, they can suffer a lot of damage from typhoons and strong winds every year. However, there is no wind load specification for rooftop signboards. In this study, wind pressure experiments were conducted to investigate the peak wind pressure on each side of rooftop signboards installed on the roofs of 5-15 story buildings in a city center. The minimum peak wind pressure coefficient was -3.0 at the bottom edges of the front and back of the rooftop signboards and -2.0 along the entire length of the sides. As the height of the rooftop signboard increased with the increasing height of the buildings, the peak value was found to be larger than the absolute peak value for the minimum peak wind pressure coefficient. The maximum and minimum peak wind pressure distributions of the rooftop outdoor signboards were influenced by the position of the signboard and the wind angle.

• Journal of Korean Association for Spatial Structures
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• v.22 no.2
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• pp.57-64
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• 2022

In this paper, the physical model and governing equations of a shallow arch with a moving boundary were studied. A model with a moving boundary can be easily found in a long span retractable roof, and it corresponds to a problem of a non-cylindrical domain in which the boundary moves with time. In particular, a motion equation of a shallow arch having a moving boundary is expressed in the form of an integral-differential equation. This is expressed by the time-varying integration interval of the integral coefficient term in the arch equation with an un-movable boundary. Also, the change in internal force due to the moving boundary is also considered. Therefore, in this study, the governing equation was derived by transforming the equation of the non-cylindrical domain into the cylindrical domain to solve this problem. A governing equation for vertical vibration was derived from the transformed equation, where a sinusoidal function was used as the orthonormal basis. Terms that consider the effect of the moving boundary over time in the original equation were added in the equation of the transformed cylindrical problem. In addition, a solution was obtained using a numerical analysis technique in a symmetric mode arch system, and the result effectively reflected the effect of the moving boundary.