No abstract

A new beam structure with periodically attached multioscillators is proposed based on the idea of locally resonant (LR) phononic crystals (PCs) to reduce flexural vibrations in the frequency-multiplication ranges. Wave band structures of the new beam are derived by using the transfer matrix method. The multiple band gaps in the beam are then verified by the frequency response function (FRF), which is calculated through the finite element method. In addition, simplified models are proposed, which contribute to the calculation of the edge frequencies of the band gaps and enhance the understanding of the LR mechanism of PCs. The accuracy of the simplified models is proven by comparing them with the results derived from the analytical model under different beam structure parameters. The results suggest that lower frequencies and ranges of frequency multiplications can be achieved in the band gaps which are obtained from the new beam structure with multioscillators in a unit cell. Therefore, the ideas presented in this paper have the potential to be used in developing new devices with frequency-multiplication characteristics for vibration isolation or noise control in aerospace and civil structures.

No abstract

No abstract

FRP-confined concrete-encased cross-shaped steel columns (FCCSCs) are a new form of hybrid columns recently developed at the University of Wollongong. An FCCSC consists of a square FRP outer tube, a cross-shaped steel section and concrete filled in between. This sectional configuration ensures that the concrete is very effectively confined despite the square shape of the column. In addition, the crossshaped steel section serves as the ductile longitudinal reinforcement for loads in the two lateral directions and its possible buckling is constrained by the FRP outer tube and the concrete, leading to a column that is highly ductile. In this paper, results from a series of stub column tests are presented to demonstrate the concept of the new column form. The experimental program involved the testing of FCCSC specimens as well as four types of similar column forms, namely, square FRP-confined plain concrete columns (SFCPCs), circular FRP-confined plain concrete columns (CFCPCs), concrete-encased cross-shaped steel columns and square plain concrete columns. The test results confirmed the excellent performance of FCCSCs. The test results also showed that compared with the concrete in SFCPCs and that in CFCPCs, the concrete in FCCSCs has a much larger ultimate axial strain and a larger compressive strength, when the same FRP tube is used.