Analysis of ground snow load for greenhouse structures in Croatia

According to the commercial production greenhouses classification, corresponding design working lives are shorter than 50 years, implying the reduction of characteristic snow load in the design process. To adjust the snow load to a shorter return period, the standard EN 13031–1 provides the procedure for calculating the snow adjustment factors, which reduce the characteristic snow loads to appropriate values. On the other hand, the greenhouse structure reliability level for sustained design situations should be satisfied. This study analyses the maximum snow loads in Croatia from climatological and engineering perspectives considering the greenhouses structures. It provides a basis for determining the characteristic snow load in Croatia and for calculating adjustment factors, emphasising its impact on the greenhouse structure reliability level. General climatology of maximum snow load was performed for 73 stations covering the data period of 1968–2018. The results revealed four main climate snow regions in Croatia: mainland, mountainous, coastal hinterland, and Adriatic. Results showed that Gumbel distribution is generally a preferred member of the generalised extreme value distribution family for snow load data in Croatia. Stationary Gumbel distribution was applied since a significant temporal trend could generally not be found in the maximum snow load data. After investigating different expressions for calculating the adjustment factor available in the literature, it is suggested to use a simplified version that considers the probability of snow winter in practice. Additionally, the study points out the need to consider the large snow load coefficient of variation of diverse snow regions in Croatia in the future updates of the national annex to the standard HRN EN 1991-1-3.