Longitudinal and flexural wave propagation in reinforced concrete columns

order to investigate elastic wave propagation in reinforced concrete (RC) columns with regular rebar arrangements, longitudinal and flexural phase velocity spectra of the Floquettype harmonic waves were computed. Floquet’s theorem was applied to the regularly reinforced RC columns to incorporate the heterogeneity induced by longitudinal steel bars, tie bars, and concrete. The numerical solution of phase velocity spectra was obtained by utilizing a semi-analytical finite element (FE) method. Phase velocity spectra exhibit strong dispersion similar to the Pochhammer and Chree problem of homogeneous circular cylinders. It was found that this dispersion in acoustic (lowest) modes was not accurately predicted by the elementary theories, However, it was found that the acoustic mode shapes of the Floquet waves can be closely approximated by plane sections, consistent with the assumptions of elementary rod and beam theories. The effect of transverse steel, in the form of tie bars, on phase velocity spectra of acoustic modes was found to be negligible due to the small volume fractions. In addition, by considering square and octagonal cross sections, the effects on dispersion of both cross sectional geometry and increasing volume fractions of longitudinal bars were investigated by neglecting tie bars, 0 1997 Elsevier Science Ltd.