Spatial Variation Of Earthquake Motion Research Articles

Structural damage distribution induced by Wenchuan Earthquake on 12th May, 2008

Based on the reconnaissance of buildings in Dujiangyan City during 2008 Wenchuan earthquake, China, structural damage characteristics and the spatial distribution of structural damage are investigated, and the possible reasons for the extraordinary features are discussed with consideration of the influence of urban historical evolution and spatial variation of earthquake motions. Firstly, the urban plan and typical characteristics of structural seismic damage are briefly presented and summarized. Spatial distribution of structural damage is then comparatively analyzed by classifying all surveyed buildings in accordance with different construction age, considering the influence of seismic design code on urban buildings. Finally, the influences of evolution of seismic design code, topographic condition, local site and distance from fault rupture on spatial distribution of structural damage are comprehensively discussed. It is concluded that spatial variation of earthquake motions, resulting from topography, local site effect and fault rupture, are very important factor leading to the extraordinary spatial distribution of building damage except the evolution of seismic design codes. It is necessary that the spatial distribution of earthquake motions should be considered in seismic design of structures located in complicated topography area and near active faults.

Spatial variation of seismic motion induced by propagation of body waves

Spatial variation of earthquake ground motion is an important phenomenon that cannot be ignored in the design and safety of strategic structures. Several models have been developed to describe this variation using statistical, mathematical or physical approaches. The latter approach is not specific to an event. A recent contribution, which uses such an approach and called complete stochastic deamplification approach (CSDA), was developed [1]. The aim of this paper is to analyze the spatial variation of earthquake motion induced by the propagation of body waves using the CSDA. Coherency functions are evaluated for the cases of SH–SV–P waves propagating through stratified soil. Results obtained show that the variation of the coherency function is not the same for vertical and horizontal components and that the motion is more coherent at depth than at the free surface. In fact, we found that the rate of decrease with frequency and distance is not the same if P–SV waves propagate through stratified soil.

Reliability of an engineering system under a strong earthquake with application to offshore platforms

This paper presents a method developed for the performance evaluation of an engineering system during a strong earthquake. The seismic reliability of the system is evaluated by considering the different possible failure modes, and seismic reliability of the components of the system. The method is applied to the oil production system at the Statfjord Field in the North Sea. The objective of the analysis is to document the reliability of oil production from the field in the event of an exceptionally large earthquake, and to investigate the effect of spatial variation of earthquake loading parameters on the computed system reliability. It is shown that, with a realistic model of the spatial variation of earthquake motion, there is very little correlation between the earthquake loading parameters at different platform locations. The main consequence of this lack of correlation is that the computed failure probability of the oil production system under the design earthquake is about one order of magnitude smaller than the probability of failure of individual platforms at the Statfjord Field.

Influence of spatial variation of earthquake motion on response of gravity base platforms : Nadim, F; Vanmarke, E H; Gudmestad, O T; Hetland, S Struct SafetyV10, N1–3, May 1991, P113–128

Influence of spatial variation of earthquake motion on response of gravity base platforms : Nadim, F; Vanmarke, E H; Gudmestad, O T; Hetland, S Struct SafetyV10, N1–3, May 1991, P113–128

Influence of spatial variation of earthquake motion on response of gravity base platforms

Influence of the spatial variability of earthquake ground motion on response of large North Sea gravity base platforms is studied. The seismic environment is described as a random field varying in both space and time. An approximate procedure for evaluation of kinematic interaction for incoherent free field motions is developed. Changes in the earthquake response of two gravity base platforms of Condeep design, caused by the local partial coherence of free field motions, are evaluated. Other aspects of the spatial variation of earthquakes that might be of interest for offshore oil fields are also discussed.