Planar Compress Wave Scattering and Energy Diminution Due To Random In-Homogeneity of Material Density


Abstract eng:
Slender engineering structures are endangered by a surface seismic wave. Subsoil parameters include a significant random inhomogeneity, which strongly influences character, spectral composition and intensity of such waves. Therefore, the seismic shock in a certain distance from the epicenter changes its degree and type, depending on a random character of the subsoil parameters in the positive but also in the negative meaning of the term. The paper investigates the compress wave propagation in two-dimensional continuum, the density of which is a continuous random function of x,y coordinates. This basic concept refers materials with in-homogeneity, which are encountered in subsoil being attacked by seismic wave. The random in-homogeneity influences significantly the wave structure and energy diffusion due to scatter at in-homogeneities. The density consists of a constant mean value and density fluctuations. Relevant centered two-dimensional random process is considered to be Gaussian, stochastically homogeneous and ergodic in x,y coordinates. The integral spectral decomposition in space is employed to derive the governing integro-differential system. It includes unknown deterministic component of the response and functions characterizing its random part. An approximate supposition that Gaussian imperfections lead to non-centered Gaussian response is adopted. There is shown a steep drop of the response deterministic part and a simultaneous increase of the response uncertainty (stochastic part) with raising distance from the point of excitation. These processes don't represent any mechanical energy loss, but only changes of its form. An upper limit of the excitation frequency (critical frequency) depending predominantly on the mean correlation length of imperfections has been found. Some ideas of application in earthquake engineering are given.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
Rights:
Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 48.:
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