I am using the aluminum design manual equations to design an aluminum column that fixed at the base and free at the top, so fixed-free end conditions. Section C.3 of the Aluminum Design Manual says to use an effective length factor of k=1 for all members. The effective length factor for fixed-free columns is 2.It seems like I cannot use the equations in the manual and will have to use theoretical equations (eulers/secant). When using k=2 and the design manual equations my allowable stress was extremely low.
Below is the excerption from a Guide (attached) to the US Aluminum Design Specification for your use in comparing the US design considerations and your design code/specifications. I think the two are similar in this regard.
- The Effective Length Factor (k) The effective length factor (k) is multiplied by the actual unbraced column length (L) to obtain the length between points of inflection, or the length of Euler’s pin-ended column. The k factor is a measure of the restraint against rotation and the resistance to lateral deflection at the ends of the unbraced length. Figure 5.20 gives k values for various cases. Aluminum Specification Section 3.2, Nomenclature, requires that k be taken as larger than or equal to 1 "unless rational analysis justifies a smaller value."