Transverse vibrations of trusses

Abstract

Lumped mass methods have been extensively used to obtain natural frequencies and mode shapes of beams in transverse vibration. Lumped inertia methods have also been used in studying vibration characteristics of beams and girder floors. In this paper characteristics of transverse vibrations of pin jointed trusses are obtained by the use of a rational method of lumping inertia forces. The effective inertia force at each joint is determined by considering the distribution of inertia force in all the members meeting at the joint. Natural frequencies of transverse vibration obtained by this method are compared with those obtained by the method of lumped masses and the discrepancies are found to be considerable particularly at higher frequencies. A method of condensing matrices to obtain natural frequencies is also included.