| Summary: | 碩士 === 國立中興大學 === 土木工程學系所 === 105 === It has been reported that facade frame type scaffolds (FFTS) used in domestic buildings under construction collapsed occasionally in the period of typhoon and the major reason of the failure of FFTS was due to the action of strong wind. Over the last few decades, local engineers have adopted the strength of wind loads to design FFTS based on the “Design Specifications of Resisting Wind Load for the Buildings” in Taiwan. However, a precise design analysis was difficult to achieve due to lack of detail wind load information.
In the study, a model of a scaffolding system, built at one side of the exterior surfaces of a medium-height building with a square cross-section, was set in the wind tunnel to measure the wind forces on the system in various oncoming wind flow directions. The building was considered in an open terrain with a ground condition subject to type C exposure. The scaffolding system with additional protecting clad sheets at three porosity ratios (0%, 15% and 30%) were tested to investigate its wind load effect. In addition, the net pressures on the scaffolding system were also measured in the case that the clad sheet was impermeable.
Results show that a decrease of the sheet porosity ratio tends to promote a more significant extent of wind force variation of the system with respect to the change of the oncoming-flow direction. As the scaffolding system is set at the windward side of the building, a maximum total push-in force occurs. When the orientation of the scaffolding system is parallel to the oncoming-flow direction, the total pull-out force becomes a maximum. Moreover, the fluctuating part of the net clad pressure can be appreciable, compared with the corresponding local mean pressure. Finally, the net pressure of the clad varies in space and the net pressure extrema mostly occur near the edges or corners of the scaffolding system.
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