Loads - Tensile Fabric Structures: Design, Analysis, and Construction - page 55

snow load distributions is further complicated by the deformation of the structure
under loads that can be sufficient to affect sliding and melt water migration.
Generally these effects cannot be readily modeled or quantitatively studied in the
context of project design.
Fig. 4-1
Snow Drifting Model for Lindsay Park Roof
4.6 Rain Loads
Ponding instability caused by rain in the absence of other loads, such as wind or
snow, can be quantitatively addressed in non-linear analysis. In practice this is rarely
necessary, for if a portion of a tensile membrane roof surface is found not to drain
under small gravity loads, it is probable that it will pond. Generally the stiffness of
the fabric membrane structure will be found to increase with deformation but usually
not at an inadequate rate to prevent overload when a sufficient source of water is
present. In such instances the structures shape (form and prestress) will typically
require modification.
Consideration of rain on snow is discussed in Section 4.5 above.
4.7 Earthquake
Many tensile membrane structures defy easy categorization with respect to lateral
force resisting systems. Often the entire structure is engaged in resisting lateral (as
well as vertical) loads. The systems are generally quite soft and have very low mass,
especially with respect to their surface area.