concrete - filled steel tube columns - tests ... - CCVI Information

NOTATIOND outer diameter of the circular steel tubeh larger dimension of the rectangular steel tubeb smaller dimension of the rectangular steel tubet thickness of the steel tubef y yield stress of the steelE s modulus of elasticity of the steel (E a in EC4) = 200 N/mm 2 if not given by the testerf cyl cylinder strength of the concrete = 0.8f cu if cube strength given by the testerf cu cube strength of the concreteE c secant modulus of elasticity of the concrete to 0.4f cyl= 22*((f cyl + 8)/10)^0.3 if E c was not given by the testerL length of the columne eccentricity of load on the end of the column, causing end momentN uEC4 ultimate load capacity of the column as calculated using Eurocode 4N u axial load at failure in the testχ buckling factor = 1/(φ + √(φ 2 - λ ) ) where φ = 0.5*(1 + 0.21*( λ - 0.2) + λ 2 )λ slenderness ratio = √(N plRk /N cr )N plRk plastic resistance of the composite sectionN cr elastic critical load = π 2 (EI) eff /L 2(EI) eff effective flexural stiffness of the composite section = E a I a + 0.6*E c I ck factor to take account of second order effects in the simplified analysis, which,for columns with equal end moment, = 1/(1 – N u /N cr,eff )where N cr,eff uses (EI) eff,II = 0.9*(E a I a + 0.5*E c I c ) to obtain the elastic critical load