What is the definition of Ec(S), Ec(D) and Ec(V) in ETABS Composite Beam Design Output?
The modulus of elasticity for strength Design Ec(S) is taken from modulus of elasticity used in Deck Properties for LRFD design code. For ASD code, program is computing the Ec(S) based on
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33 * gamma_c^1.5 * sqrt
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. For deflection Ec(D), modulus of elasticity is computed based on Ec(S)/(Creep Factor) which is specified in Preference menu. For Vibration, the modulus of elasticity Ec(V), computed for strength is amplified by 1.35 as suggested in AISC Guide 11, page 12. Since the modulus of elasticity is changed, causing modular ratio to be different for Strength, Deflection and Vibration which produces different transformed inertias.