高層建築物の外装材に作用する風力に対する外圧および内圧の影響

Abstract

The purpose of this study is to understand the effects of the external pressures and internal pressures on the wind loads to use in wind-resistant design for the cladding of high-rise buildings. In order to measure the external pressures acting on the assumed high-rise building, a wind tunnel experiment using the reduced scale model of 1/250 was conducted. This assumed building is a high-rise building with an eaves-height of 45m having a rectangular plane width of 40m and a depth of 25m. The wind tunnel facility used in the experiment was the closed-circuit type boundary-layer wind tunnel having a testing section length of 20m, height of 2.5m and width of 3.6m. The characteristics of the boundary-layer flow used in the experiment were to match the nominal flow of the flat terrain of neutral stability conditions. The external pressures on the scale model of the assumed high-rise building were measured using the multi channel simultaneous measuring system (MCSMS). Details of the wind tunnel experiment are discussed in Chapter 2. The numerical simulation used both a leakage flow model and the external pressure was conducted to estimate the internal pressures in the assumed building induced by the wind. The leakage flow model has been constructed by applying Poiseuille's law. Details of the numerical simulation are discussed in Chapter 3. The net pressure was evaluated by subtracting the internal pressure from the external pressure. In Chapter 4 the properties of the net pressure coefficient, the external pressure coefficient, the internal pressure coefficient, and the power spectrum density distribution and probability density distribution are discussed. In Chapter 5 the correlation properties of between the external pressures and the internal pressures are discussed. In Chapter 6 the properties of the peak values (maximum and minimum) of the essential net pressure coefficients to the wind-resistant design of the cladding are discussed. Both of the largest peak net pressure coefficients and the largest peak external pressure coefficients (worst value in any wind direction) are compared with the recommendations values (2015) of AIJ in this Chapter. In Chapter 7 the method of approximating the peak net pressure using the mean internal pressure and the peak external pressure is discussed. Furthermore, in this Chapter the method approximating the peak net pressure using the peak external pressure and the peak internal pressure is also discussed. From the above results, the following findings were obtained. 1) The effects on the net pressure fluctuations of the external pressure fluctuations are more dominant than the internal pressure fluctuations. 2) The effects on the net pressures of the partitions are remarkable in case of a low airtight. 3) The probability distribution of the net pressure can be approximated by a Gamma distribution or Gauss distribution based on the skewness, the same as external and internal pressure. 4) The correlation coefficients between the external pressures and internal pressures on the cladding are almost positive values. 5) The largest (worst) maximum net pressure coefficient for any wind direction on the cladding of the assumed high-rise building of a high airtight almost agreed with the recommendation values (2015) of AIJ. 6) The tightness effects on the largest minimum net pressure coefficient are small. 7) In case of the building with a high airtight, the peak net pressure on the cladding can be approximated using the mean internal pressure and the peak external pressure. 8) The peak net pressure on the cladding obtained from the peak value of the external pressure and internal pressure is evaluated on the safety side, in case of independent.