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Designing Balcony Railings for Windy Vibrations by Mahmod Samman, PhD, PE, FASME Photo © BigStockPhoto/Chris Nolan BALCONY RAILINGS COME IN DIFFERENT SHAPES, MATERIALS, AND STYLES. WHEN RAILINGS ARE INSTALLED IN HIGH-WIND AREAS, DESIGN TEAMS MUST VERIFY THE ADEQUACY OF THEIR DYNAMIC CHARACTERISTICS IN ORDER TO ENSURE OCCUPANT SAFETY AND COMFORT. One of the most common railing designs is an aluminum frame with vertical pickets (Figure 1). The popularity of this material is attributed to a combination of factors such as: • aesthetics; • view; • strength; • durability; • lightness; • rust-resistance; and • relatively low material and installation costs. From a structural standpoint, balcony railings are primarily designed to withstand mechanical loads imposed by occupants. Since this design criterion can be easily met using a metal like aluminum, the need to produce less-expensive options resulted in products designed to minimize weight. In many applications, new lighter-weight aluminum railings still work because they satisfy structural requirements and applicable safety standards. However, in high-rise buildings, especially in coastal areas, these products can suffer from a serious, previously unknown, functional failure. The lighter structural members can become flexible enough to experience resonance under wind excitations. When this happens, the resulting noise and vibrations can make these costal properties virtually uninhabitable. Additionally, the dynamics of resonance can cause fatigue damage in these structural members that can lead to structural failure of connecting welds. 54 the construction specifier | april 2013 CS_April2013.indd 54 3/14/13 11:49:26 AM