屋面雪荷载分布风洞试验研究

Study of snow-load distribution on roof by wind tunnel test

为了预测屋面雪荷载分布,采用细石英砂粒子模拟风吹雪进行风洞试验研究,通过降雪模拟和均匀重分布试验,获得了几种典型屋面的积雪系数分布,并与中国荷载规范进行了比较。结果表明:当试验风速达到阈值风速后,测量的风洞流场有效气动粗糙长度随着风速增加而增大,显示出风吹雪边界层流场的典型特性;试验获得的阶梯形屋面积雪系数均小于中国荷载规范值;单跨双坡屋面的迎风屋面积雪系数可能会超过荷载规范值,特别是20°屋面,而10°屋面积雪系数随时间发展逐渐减小,并最终在规范值之内。在模拟降雪试验中,双跨双坡屋面的第一个迎风屋面积雪系数相对较大,但小于荷载规范值;在均匀重分布试验中,双跨双坡屋面的最大积雪系数均在第一个背风屋面的屋脊后方,其值接近1.5,超过了荷载规范值。

In order to predict the snow-load distribution on a roof, wind tunnel tests were conducted with fine quartz-sand to simulate snow particles. The snow coefficients of several typical roofs were obtained through snowfall simulation and redistribution tests, and were compared with the load design of building structures. The results show that, when the wind speed exceeds the threshold value, the efficient aerodynamic-rough-length increases as the wind speed increases; the snow coefficients of the stepped roof obtained in the tests are within the load specifications; for the single-span gable roof, the snow coefficients of the windward roof may exceed the load specifications, particularly for the 20° roof, while the 10° roof snow coefficients decrease with time and finally fall into the range of load specifications; for the double-span gable roof, in snowfall simulation tests, the largest coefficient lies on the first windward roof, the value of which is less than the load specifications, while in the simulation redistributions test, the largest coefficient lies on the first leeward roof, the value is approximately 1.5, larger than the load specifications.