Note that the loadings below are only applied when users choose to perform “Detailed” Structural and Geotechnical optimization.
Dead Loads (D)
Include PV Panel weights plus the self-weights of various components that comprise the structure. Dead loads are applied along the rake length of Array surfaces (i.e. as a downward load along the slope).
HST Defaults:
1- Panel weights = 3 psf
Wind Loads (W)
Calculated in accordance with the provisions of ASCE 7-10, Section 27.4.3, Main Wind Force-Resisting System (Directional Procedure) for Open Structures with Monoslope “PV Panel” Roofs. Wind loads are applied normal (perpendicular) to array surfaces.
HST Defaults:
1- Kd = Wind Directionality Factor = 0.85
2- Kz = Velocity Pressure Exposure Coefficient at height z = 0.85
3- KZT = Topographic Factor = 1.0
4- G, Gust Effect Factor = 0.85
Seismic loads (E)
Calculated in accordance with the requirements of ASCE 7-10, Chapters 12.4 and 12.8. Both lateral and vertical components of the seismic loads are determined.
HST Defaults:
1- Ip = 1.0 Component importance factor
2- Rp= 1.25 Component response modification factor
Snow loads (S)
Calculated in accordance with the requirements of ASCE 7-10, Chapter 7. Snow loads are applied to the horizontal projection of array surfaces.
HST Defaults:
1- Ce = 0.9 (using Terrain Category C and Fully Exposed Exposure).
2- Ct = 1.2 (Using unheated and open air structures).
3- Is = 1.0 (Using Risk Category II).
Combinations of Loads
Determined in the previous sections will be considered to act on racking structures and foundation elements using Allowable Stress Design combinations of ASCE 7-10, Section 2.4.1.
- D
- D + S
- D + 0.75S
- D + 0.6W
- D + 0.7E
- D + 0.75(0.6W) + 0.75S
- D + 0.75(0.7E) + 0.75S
- 0.6D + 0.6W
- 0.6D + 0.7E