Inside of the building's temperature can increase or reduce the snow weight. As these types of structures normally cover a wide area and heating or even turning the temperature to something higher than 0 degree needs a lot of energy and not cost effective, therefore thermal coefficient of 1/1 is being used.
As in most cases spatial structures are used outside the cities, such as sport centers and airports, a coefficient of 0.7 seems appropriate.
ANSI regulation, determines the ground snow weight in each area by dividing America into different areas. Bear in mind that we can use the top equation in Iran, if we use 0.7 Pg for the snow weight of flat surfaces in each four areas of the city. Therefore 150 kg/m2 is used for 0.7 Pg (19). therefore:
In these types cylinder roofs, as the gradient is variable, we can divide a arched roof into some slope surfaces and determine Cs coefficient for each part individually.