u \u03d5 R n \u03d5 R n Design Strength R n Nominal Resistance Strength \u03d5 Resistance

U ϕ r n ϕ r n design strength r n nominal

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u ϕ R n ϕ R n = Design Strength R n = Nominal Resistance (Strength) ϕ = Resistance Factor Nominal strength and Resistance factors defined by AISC Specification Depends on component designed Nominal strength for tension, compression, flexure, shear, etc.
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8 LRFD (Load and Resistance Factor Design) Resistance Factor accounts for variability and uncertainty Inaccuracies in theory Variations in material properties, dimensions, erected position, etc. Depends on failure mode and warning of failure Does not account for gross error / negligence Resistance Factor 1.0 (closer to 1.0, less uncertainty)
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