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In this paper, the dynamic response of a periodic pile-supported viaduct to a moving loading when considering the pile-soil-structure interaction is investigated. By using the Duhamel integral, the Fourier and Floquet transform methods, the frequency domain response of the viaduct to the moving loading is represented by an integral of the frequency-wavenumber domain response function over the representative span of the viaduct. The time domain response of the viaduct can be retrieved by the inversion of the Fourier transform. By means of the wavenumber domain boundary element method model for the periodic pile row supporting the viaduct, the compliances of the pile row are obtained. Employing the compliances of the pile row and coupling the superstructure of the viaduct with the pile row, the frequency-wavenumber domain response function of the viaduct is determined. With the proposed model, the dynamic responses of the pile-supported viaduct to the moving loading in both the frequency and time domains are presented. It is found that resonance peaks of the frequency domain response of the viaduct are more likely to occur in the passbands of the viaduct, and the number of the resonance peaks decreases with increasing velocity. When the velocity of the loading is small, the time domain response of the viaduct is almost symmetrical about the loading. However, as the velocity increases, the response of the viaduct becomes asymmetric. Further, when the velocity of the loading is large enough, shockwave-like vibration occurs in the periodic viaduct. [ABSTRACT FROM AUTHOR]

In this study, the wave localization in a disordered periodic bridge (DPB) with the pile-soil-water-structure (PSWS) coupling is investigated For simplicity, each span of the bridge is assumed to be composed of a pile foundation, a pier, two composite beams and three linking springs. To determine the compliances of the pile foundations, the pile-soil-water (PSW) interaction is simulated by the boundary element method (BEM). In terms of the compliances of the piles and the transfer matrices of the piers and beams, the transfer matrices of the spans of the periodic bridge are derived, by which the wave transfer matrices of the spans are obtained. Using Wolf's algorithm and the wave transfer matrices obtained, the localization factor characterizing the wave localization in the DPB is determined. With the proposed model, the effect of the beam-length disorder on wave localization is examined. Moreover, based on the wave transfer matrix method, the wave mode of a DPB segment and the wave conversion and power flow in the DPB segment are investigated. Numerical results show that due to the energy transmission from the superstructure of the bridge to the half-space soil via the pile foundations, the power flow associated with a complexband wave along the open DPB is usually nonzero and the power flow of a pseudo passband wave along the spans of the open DPB is no longer a constant. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a numerical model is developed to investigate the dynamic response of a defected periodic bridge (DPB) when considering pile–soil–water–structure (PSWS) interaction. In order to determine the dynamic response of the DPB, the DPB is decomposed into three parts – left and right semi-infinite periodic bridges and the defected span. To account for the coupling between the superstructure of the bridge and the pile foundations, a coupled boundary element method (BEM) model is used to model the pile–soil–water (PSW) interaction. By using the PSW BEM model, the transfer matrices for the pier and beam, the joint condition at the beam–beam–pier (BBP) junction, the response of the DPB to the characteristic wave is obtained. To investigate the relation between the response of the DPB and the defect state of the corresponding super-cell, the super-cell method is developed for the DPB. Numerical results for the energy bands of the super-cell show that the defected span of the DPB may give rise to additional passband frequencies, namely, the defect state frequencies. Moreover, when the DPB is subjected to a characteristic wave with frequency equal to the defect state frequency, resonance may occur and the response of the DPB corresponding to the resonance is localized around the defected span. [Copyright &y& Elsevier]

In this study, a new kind of pile structure, namely linked periodic pile rows, is proposed for the vibration isolation facility. The proposed linked periodic pile rows consist of pile rows with pile tops rigidly linked by beams. To investigate the vibration isolation effect of linked pile rows, a numerical model is developed for the simulation of the dynamic response of linked pile rows. To address the pile-soil interaction problem, based on the sequence Fourier transform method, a wavenumber domain boundary element method is developed for the pile-soil system. The beams linking the pile tops are dealt with by the bar and beam vibrational theories. By using the coupling conditions between the pile tops and linking beams as well as the periodicity condition for the beam-pile-soil system, the complementary equations for the system are established. With the proposed model, the vibration isolation effects of the linked pile rows are investigated and compared with those of free pile rows. The comparison indicates that linked pile rows usually yield a better isolation vibration effect than free pile rows. Hence, linked pile rows are a more effective wave barrier for vibration isolation than free pile rows. [ABSTRACT FROM AUTHOR]

Abstract: A numerical model is developed to analyse the isolation of moving-load induced vibrations using pile rows embedded in a layered poroelastic half-space. Based on Biot’s theory and the transmission and reflection matrices (TRM) method, the free wave field solution for a moving load applied on the surface of a layered poroelastic half-space and the fundamental solution for an harmonic circular patch load are determined. Using Muki and Sternberg’s method, the second kind of frequency domain Fredholm integral equations for the dynamic interaction between pile rows and the layered poroelastic half-space are derived. The time domain solution is recovered via inverse Fourier transform in order to obtain the amplitude reduction ratio and thus assess the vibration isolation efficiency of pile rows. A special case of the present model shows good agreement with an existing solution. Numerical results of this study show that the speed of moving loads has an important influence on the isolation of vibrations by pile rows: the same pile rows can achieve better isolation efficiencies for higher speed loads than for lower speed loads. Pile rows embedded in a two-layered poroelastic half-space with a softer overlying layer usually generate better vibration isolation effects than those with a stiffer overlying layer. Finally, better isolation vibration may be realized by increasing the pile length and decreasing the net spacing between neighboring piles in a pile row. [Copyright &y& Elsevier]

The dynamic response of a single pile embedded in a layered poroelastic half-space to an axial harmonic load is investigated in this study. Based on Biot’s theory, the frequency domain fundamental solution for a vertical circular patch load applied in a layered poroelastic half-space is derived via the transmission and reflection matrices method. Utilizing Muki and Sternberg’s method, the second kind of Fredholm integral equations describing the dynamic interaction between the layered half-space and the pile subjected to a harmonic axial load is constructed. The proposed model is validated by comparing a special case of our model with an existing result. Based on numerical results of this paper, it is concluded that the presence of a stiffer or a softer middle layer in the layered half-space will affect the impedance of the pile considerably and the inhomogeneity of the half-space will enhance the pore pressure significantly. [ABSTRACT FROM AUTHOR]