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The following assumptions apply to all wind load generation methods:
Windward z Value
For windward roofs and walls, the design standards require that you evaluate pressures at each point z on the vertical profile of the surface. In creating the wind load that is transferred to a diaphragm, Shearwalls integrates the varying pressure values p(z) over the whole surface. The value z reported in the Wind Load Generation Details file is the height that has a corresponding pressure p which if it was applied to the whole surface would give the same total load.
For walls, the surface in question is the upper half of the wall on the level below the diaphragm combined with the lower half of the wall above. For a roof or a gable end, it is just one of the automatically generated panels.
The program takes into account the tapering of a hip or gable in integrating pressures.
Interpolation
In all cases, if the design standard allows or stipulates that the design values in tables are interpolated, then the program interpolates. In many cases, the interpolation is done in two parameter dimensions.
Internal Pressures
The program does not consider internal pressure in the generation of MWFRS loads. The net horizontal components of the internal pressure acting on opposing wall and roof surfaces are equal in magnitude and will cancel each other.
Internal pressures are considered for component and cladding loads.
Uplift Loads
Shearwalls does not generate wind uplift loads. These must be input manually to determine the effect on hold-down forces.