SIMPLE METHOD TO STABILIZE I-BEAMS AGAINST LATERAL BUCKLING

Lateral restrained and free buckling of I-beams often represent a limi ting factor in their bending performance. Consideration of this become s increasingly more important when the engineer seeks full advantage o f new thermomechanically rolled high-yield-strength steels. The writer s present a solution to this problem consisting of warping-preventing devices in form of U-sections connected to the web and flanges of the I-section. General expressions based on Fourier expansion of the displ acements, enabling the determination of the elastic critical loads giv en the characteristics of the stiffeners (i.e., number, stiffness, and position along the axis of the I profile) are developed. Typical exam ples illustrate that the proposed stiffeners are very efficient, in pa rticular if they are placed near their optimum position. Therefore the same examples show the efficiency of the stiffeners as a function of their position. Just one or two stiffeners near their optimum position s increases the elastic critical stress by a multiplier in the range 2 to 4.