On modeling of earthquake wave motion and its effects on multi-support pipelines

Lifeline systems, such as pipelines, bridges and communication transmission systems, are important infrastructures of cities and urban communities. The functional reliability of these lifelines after an earthquake, therefore, is essential to the safety and health of the populace. The spatial variation of seismic ground motion is an important consideration for the seismic design of lifeline structures supported on extended foundations or on multiple supports. The temporal and spatial variability of seismic ground motion is effectively described by the frequency-wave number spectra, which provide complete information concerning the corresponding correlational characteristics of earthquake wave motions. In this work, an engineering synthesis is carried out for seismic ground motion and above-ground lifeline structures. The seismic ground motion on the free surface of an elastic half-space, induced by a simple seismic source characterized by a double couple, is modelled as a stochastic wave, according to its analytically derived frequency-wave number spectra, and simulated using an extension of the spectral factorization method. Subsequently, the effects of the earthquake ground motion on a multiple supported pipeline are analyzed within the framework of the finite element method.