Optimum Design of Intermediate Support for Raising Fundamental Frequency of a Beam or Column under Compressive Axial Load

Abstract

The optimum design of an additional intermediate support is investigated for raising the fundamental natural frequency of a beam or column subjected to compressive axial loadings. First, the criterion that constitutes the general characteristic equation of the optimal attachment position is explicitly provided so that an objective value of the fundamental frequency can be achieved with the minimum restraint stiffness of the intermediate support. Then, the optimum design of an intermediate support is performed for three illustrative beams of different classical boundary conditions to demonstrate the effects of the compressive axial loads. Numerical results show that the axial load can remarkably influence the support design of its optimum position and minimum stiffness when using it to increase the beam fundamental frequency.