Optimum Design of Columns Supported by Tension Ties

A rational procedure for the optimization, on a weight basis, of columns supported by tension ties is developed. The tension ties provide a degree of intermediate elastic support which renders these systems more efficient than simple tubular columns in regions of low structural index P/L². Two different configurations are considered. The first has one intermediate support-plane, and is stable up to a compressive load at which the second buckling mode occurs. The second has three intermediate support-planes and remains stable up to a compressive load corresponding to the fourth mode shape. Results are presented in such a fashion that conditions under which tie supported columns are more efficient than simple columns are readily apparent, and such that all design parameters are obtainable with a minimum of computational effort. Examples are included. Results indicate that, in favorable circumstances, columns supported by tension ties may be constructed with approximately half the weight required for a simple column capable of transmitting the same load over the same distance.