A Simple Approximation for the Fundamental Frequencies of Two-Span and Three-Span Continuous Beams

摘要

A rapid approximate method is presented for calculating thefundamental frequencies of flexural vibration of two-span beams and ofparticular arrangements of three-span beams which are continuous overnon-deflecting supports and are elastically restrained against rotationat their end supports. The end restraints may be provided by actualcoil springs or they may represent the effect of adjoining members, butin all cases the stiffnesses of these restraints are assumed to be positive.The mass per unit of length and the flexural rigidity of the beamsmay vary from one span to the next, but in any one span these quantitiesare considered constant. Two numerical examples are included to illustratethe application of the method.