Column stability and minimum lateral bracing:: Effects of shear deformations

Stability equations that evaluate the elastic critical load of columns in any type of construction with sidesway uninhibited, partially inhibited, and totally inhibited including the effects of bending and shear deformations are derived in a classical manner. The "modified" shear equation proposed by Timoshenko and Gere is utilized in the derived equations which can be applied to the stability of frames ("unbraced," "partially braced," and "totally braced") with rigid, semirigid, and simple connections. The complete column classification and the corresponding three stability equations overcome the limitations of current methods. Simple criteria are presented that define the concept of minimum lateral bracing required by columns and plane frames to achieve nonsway buckling mode. Four examples are presented that demonstrate the effectiveness and accuracy of the proposed stability equations and the importance of shear deformations in columns with relatively low shear stiffness A(s)G such as in built-up metal columns or columns made of laminated composites (fiber-reinforced polymers).