Abstract
This paper describes a stochastic model for predicting the wind-induced damage to residential houses in Tohoku District due to typhoons. First, an investigation was made of the damage to residential houses due to Typhoon No.19 in 1991 (Typhoon 9119), which struck the Tohoku District and caused severe wind damage. The results indicate that most damage was caused to cladding, in particular to roofing materials. Then, a stochastic model for predicting the typhoon wind damage to cladding has been developed. The model consists of ‘typhoon model’, ‘local pressure model’and‘wind resistance model’ . For constructing the‘typhoon model’, the statistical characteristics of the atmospheric pressure patterns of 68 typhoons, which struck the Tohoku District during the period of 1954 to 1996, were analyzed and specified. The time change of the typhoon parameters, which specify the pressure pattern, between lat.37 to 42° N were represented by simple functions of time. Based on a computer simulation (typhoon simulation) using this‘typhoon model’, the statistical characteristics of strong winds due to typhoons can be understood quantitatively. The effects of topographic factors on wind speeds were investigated by using a multivariate regression analysis. In the‘local pressure model’, the roof geometry is classified into two groups, i.e. gable and hip roofs, and the local pressure coefficient is specified for each group, based on the results of the previous wind tunnel experiments. The value of the peak pressure is assumed to be predicted by a quasi-steady approach. Therefore, the probability density function of the local peak pressures is obtained by combining this model with the results of the typhoon simulation. In the‘wind resistance model’ of cladding, the probability density function of the strength of cladding is assumed to be represented by the log-normal distribution; the mean was predicted from the damage rate of cladding due to Typhoon 9119. Finally, the results of a damage simulation made for Hirosaki City are presented and the characteristics of the wind damage to roof are discussed.
