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Zhao Huiming¹, Dong Zhengzhu, Chen Jiarui, Yang Min
Structural Longevity, Vol.5, No.2, pp. 59-67, 2011, DOI:10.3970/sl.2011.005.059
Abstract The advantage of the coupling method of natural boundary element method(NBEM) and finite element method (FEM) is introduced firstly. Then the principle of the direct coupling method of NBEM and FEM, and its implementation, are discussed. The comparison of results between the direct coupling method and FEM proves that the direct coupling method is simple, feasible and valid in practice. More >

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A.P.S. Selvadurai¹
Structural Longevity, Vol.5, No.2, pp. 69-76, 2011, DOI:10.3970/sl.2011.005.069
Abstract The compaction of soils can lead to soil profiles that have properties that are less desirable from the point of view of agricultural use of soils. The paper presents elementary models of soil compaction based on continuum theories of poro-elasto-plasticity. Attention is restricted to the consideration of the quasi-static loading of a saturated one-dimensional column of soil that can experience fluid flow in its pore space and reversible and irreversible deformations of the porous skeleton. More >

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Jiancheng Xu¹, Yong Li¹
Structural Longevity, Vol.5, No.2, pp. 77-82, 2011, DOI:10.3970/sl.2011.005.077
Abstract We propose a non-iterative approach to extract the unknown phase shift in phase shifting interferometry without the assumption of equal distribution of measured phase in [0, 2π]. According to the histogram of the phase difference between two adjacent frames, the phase shift can be accurately extracted by finding the bin of histogram with the highest frequency. The main factors that influence the accuracy of the proposed method are analyzed and discussed, such as the random noise, the quantization bit of CCD, the number of fringe patterns used and the bin width of histogram. Numerical simulations More >

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S.J. Zhu¹, Q.H Zeng, J.J Lou, Q.W He
Structural Longevity, Vol.5, No.2, pp. 83-96, 2011, DOI:10.3970/sl.2011.005.083
Abstract Line spectra are the most visible signs of the ships’ radiated noise spectrum. The potential of chaotifying vibration isolation systems to reduce line spectra and improve its capability of concealment have been recently reported. Basically, as the existing isolation system design is based on linear theory, it is difficult to produce the nonlinear chaotic motion; and if the vibration isolation system(VIS) is designed directly using the nonlinear theory, it is also difficult to produce the chaotic motion because of the difficulties in accurate calculation of vibration isolation device parameters. In this paper, a controller design More >

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Z.G. Guo¹, Z. Sun¹
Structural Longevity, Vol.5, No.2, pp. 97-106, 2011, DOI:10.3970/sl.2011.005.097
Abstract An efficient approach to identify multiple cracks in a slender beam using the frequency response function data is presented. It is formulated in a general form from the dynamic stiffness equation of motion for a structure and then applied to a slender beam. The cracks are modeled by rotational springs and the frequency response function is computed based on a spectral element model by the spectral finite element. The procedure gives a linear relationship explicitly between the changes of the measured frequency response function and crack parameters. The inverse problem is solved iteratively for the More >

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Jianglin Xu¹, Zhi Sun²
Structural Longevity, Vol.5, No.2, pp. 107-115, 2011, DOI:10.3970/sl.2011.005.107
Abstract The measurement of residue prestress force is one main issue for condition and performance assessment of prestressed concrete beam bridge. This paper proposes a vibration based parameter estimation technique for this purpose. Under given form external excitation, beam velocity responses at multiple points are collected firstly. The prestress force of the beam is then identified based on the minimization of the least square difference between the measured response and the baseline response. A numerical study on a beam of variant length, subjected to a constant prestress force with variant eccentricity, is conducted to show the More >

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