According to the provided technical guide, the ASCE 7-22 standards establish specific safety factors and load combinations to determine the required uplift resistance capacity for helical piers in solar applications.
Key requirements include:
- Governing Load Combinations: For solar arrays subjected to wind uplift, the combination 0.6D + W (Dead load + Wind) typically governs the design.
- Minimum Factors of Safety: ASCE 7 mandates a minimum factor of safety of 1.5 for dead loads and 2.0 for live and wind loads when designing piers for uplift.
- Regional Adjustments: In specific conditions, such as regions with expansive clay (e.g., Texas), moisture fluctuations can reduce pier capacity. In these instances, a higher factor of safety—typically 2.5 instead of 2.0—is recommended to ensure stability.
- Lateral Loading: When designing for lateral loads, which often occur simultaneously with uplift in solar foundations, ASCE 7 may require combinations such as 1.0W or 1.2D + 1.6L + 0.5W.
Engineers must use these factored loads in capacity equations and verify them through site-specific load testing and software modeling to ensure compliance with building codes.
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