采暖建筑结构屋面雪荷载实测研究

In order to explore the influence of the building thermal environment on the roof snow load, a prefabricated building model for actual measurement was designed based on the requirement of the law of thermal coefficient (C_t) in foreign building load codes (ASCE/SEI 7-10 and ISO 4355:2013). The proposed model can change the heat resistance of roof and indoor temperature. In detail, the actual measurements of apparent density of snow and snow load under natural snow (with low moisture) and artificial snow (with high moisture) conditions in both the snowmelt period (with daily maximum temperature higher than 0℃) and the non-snowmelt period (with daily maximum temperature not higher than 0℃) were completed. The results show that the snow-layer on the building roof in the snowmelt period experiences the stages of the melt of lower surface snow, and then upward movement of melt layer with discharge of the snowmelt water. The apparent density and environmental temperature of snow show a positively correlated relationship while the variation of snow load appears a typical three-stage form, including the melting, the mass-loss and the recrystallization. Besides, the variation of snow-layer on the building roof in the non-snowmelt period is less than that in the snowmelt period, but the trend is highly consistent, where the snow load decreases with the increasing of roof heat loss. Finally, according to GB 50189-2015 and JGJ 134-2010, the thermal coefficient values of all measured conditions were calculated, and the C_t value of the building with the indoor maximum temperature about 0℃ was suggested to be 1.2.