"Factored" loads increase the design burden based on the uncertainty of the load type (e.g., higher factors for live loads vs. dead loads).
Applies a single Factor of Safety to the material's ultimate strength to determine "allowable" stresses. Loads: Uses actual expected (unfactored) service loads. Structural wood design: ASD/LRFD
Applies separate factors to both loads (Load Factors) and material strength (Resistance Factors). "Factored" loads increase the design burden based on
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) Loads: Uses actual expected (unfactored) service loads
Standard in steel and concrete design and gradually gaining ground in the wood industry. ⚖️ Key Differences for Designers Load Factors Usually 1.0 (unfactored) Multipliers > 1.0 (e.g., 1.2, 1.6) Material Strength Reduced by Factor of Safety Multiplied by resistance factor ( Calculations Stress-based ( Strength-based ( Efficiency Can be conservative for mixed loads More efficient for transient load combinations 🪵 Why Choose One Over the Other?
Modern, reliability-based method that uses statistical probability .
"Factored" loads increase the design burden based on the uncertainty of the load type (e.g., higher factors for live loads vs. dead loads).
Applies a single Factor of Safety to the material's ultimate strength to determine "allowable" stresses. Loads: Uses actual expected (unfactored) service loads.
Applies separate factors to both loads (Load Factors) and material strength (Resistance Factors).
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)
Standard in steel and concrete design and gradually gaining ground in the wood industry. ⚖️ Key Differences for Designers Load Factors Usually 1.0 (unfactored) Multipliers > 1.0 (e.g., 1.2, 1.6) Material Strength Reduced by Factor of Safety Multiplied by resistance factor ( Calculations Stress-based ( Strength-based ( Efficiency Can be conservative for mixed loads More efficient for transient load combinations 🪵 Why Choose One Over the Other?
Modern, reliability-based method that uses statistical probability .