BRACING FOR COLUMNS WITH INITIAL DEFORMATION SUBJECTED TO VARYING AXIAL FORCES IN A STAIRCASE PATTERN

摘要

As is well known, the bracing frames of the compressive members should have sufficient stiffness and strength to resist the external forces. And the initial imperfections cannot be neglected in the real structures. This paper is concerned with the relation between the nondi-mensional axial force and the rotational angle when the both ends of the member with an initial deformation are subjected to axial forces that vary in a staircase pattern. One brace is set in the middle to support the whole member and there is an initial deformation at the same place. The load-deflection relationship of the members subjected to varying axial forces is calculated by using the buckling slope deflection method. In addition, the comparisons among the axial force, the stiffening force and the nondimensional bracing stiffness are presented by choosing the ratio of axial forces, the nondimensional bracing stiffness and the initial rotational angle as the parameters.