Basic concepts

In those cases where a tensile structure is situated in an area where it snows regularly, snow load is usually greater than the wind load and could become a real problem for the structure. The different regulations usually set a constant snow load for the different areas and different altitudes in each country. This snow load corresponds more or less the thickness produced by a heavy snowfall or the accumulation of snow when the cold prevents melting of snow. The worst case can be that the fresh snow acting as sponge absorbs rain water that might happens later.

Whatever it is, the snow load is considered a uniform load on the surface projection. It is important to understand that the same snow falls on an inclined surface and on its projection in the X,Y plane are the same, even if the inclined surface is larger than the flat surface.

Another major problem with snow is the accumulation caused by the wind in certain areas. Moreover, it is very unlikely that the snow will thicken on surfaces with a steep gradient. Normally it will tend to fall to the ground or on another area of the cover. WinTess3 does not analyze these peculiarities, and in any case it must be the user who will apply loads directly at nodes to simulate this inbalance.

WinTess3 and snow

Applying snow load in WinTess3 program is done through the window of surface loads which can be accessed by F6 key or the menu Calculate | Surface loads.

We will enter the value of the load in the box of snow as kg/m². The program distributes the area of the triangles between its three apexes following the same criterion as the one that has been used for the wind. The most important difference is that only distributes the projection in the XY plane of the triangle area, not its complete area as we do in the case of wind or pressure.

We can enter actions of wind and snow at the same time. We must remember that the calculation is not linear and therefore it is not the sum of the results obtained when you calculate a structure for wind and snow loads separately.
We can visualize the snow loads applied by the button on the right .

Non-uniform loads

In the event that we wish manually modify the uniform distribution of the load of snow, we can use the menu Calculate | Cn (snow) to modify these loads. In this way we can simulate non-uniform loads  due to protected areas of the snow, areas of accumulation of snow by the wind, asymmetries …

We can visualize Cn values for each element at any time using the Cn button of the on the right column.