Probabilistic Dynamics of Wind Excitation on Glass Facade

In recent years there are many buildings the facades of which are filled with glass material. As this tendency continues, new types of glass material, support system and structure have been developed. On the other hand, wind is one of the main loads on the glass facades and it is a dynamic load. However, dynamic character of these new facades are not known and glass is known to have low damping. The danger of vibrations on glass facades caused by wind is pointed out. The first aim of this study is to estimate the dynamic character of the glass facade and to obtain the dynamic wind load on a glass facade. First, the characters of natural dynamic wind were studied and velocity pressure of natural wind was numerically produced. Vibration of the glass facades under fluctuating natural wind were simulated in time series. The simulation has been carried out on glass facades with ESG (Einscheiben-Sicherheits-Glas; Single Panel Safety Glass), with areas of 2.5-6.0m2. The glass plates are along the edges linearly supported or at the points by the fittings. The results of the time series simulations were transformed into spectra by FFT(Fast Fourier Transform). In the spectrum of the deformation of the large surface area and point-support glass, the resonance effect are recognized around the first natural frequency of the facades. By using results of the time series calculation of motion of the facade, the motion-induced wind load is calculated backwards. The sum of the fluctuating natural wind load and the motion-induced wind load is the total wind load which acts on the facade element. The problem of fatigue for the glass material is pointed out and a fatigue analysis is needed. For the fatigue analysis of glass, the S-N curve (Wohler curve) and loading-cycle are necessary. The second aim of this thesis is to estimate the loading-cycle of wind during the lifetime of the facade. There are a few counting methods of the loading-cycle from a time series random force. But in this study a new method to make a loading-cycle model from a spectrum of the load is suggested. By using the spectrum, frequency information is well reflected in the loading-cycle model. First, the loading-cycle of 10 minutes under each wind condition was calculated by using this new method. Then the loading cycle model which is equivalent to the entire lifetime of the structure is probabilistically derived. Appearance ratio of the 10 minute mean wind velocity is known to fit the Weibull distribution. Considering a loading-cycle of each 10-minute wind and the appearance ratio of these wind conditions, the loading cycle model of 50 years can be calculated. By using this method, loading-cycles on glass facades built at heights of 20 m and 50 m for buildings that are located in Frankfurt and Hamburg were calculated.