Remains the historical standard for wood and is widely used due to its simplicity and the extensive existing library of hardware catalogs based on ASD. Load and Resistance Factor Design (LRFD)
In modern structural engineering, designers of wood systems must navigate two distinct philosophies: and Load and Resistance Factor Design (LRFD) . Both are currently accepted by the National Design Specification® (NDS®) for Wood Construction. 🏗️ Design Philosophies Allowable Stress Design (ASD)
"Factored" loads increase the design burden based on the uncertainty of the load type (e.g., higher factors for live loads vs. dead loads). Structural wood design: ASD/LRFD
Applies a single Factor of Safety to the material's ultimate strength to determine "allowable" stresses. Loads: Uses actual expected (unfactored) service loads.
Modern, reliability-based method that uses statistical probability . Remains the historical standard for wood and is
Traditional, deterministic method based on elastic design .
Applies separate factors to both loads (Load Factors) and material strength (Resistance Factors). Loads: Uses actual expected (unfactored) service loads
The choice often depends on the specific project requirements or the engineer's preference: LRFD versus ASD for Wood Design