Regarding the nonlinear behavior of soil and pipes in strong earthquakes, in this study the possible damages in straight continuous steel buried pipelines subjected to strong surface transverse waves has been investigated, and a relationship between the maximum compressive strain and the pipe reduced hollow-section area has been presented. For this purpose at first the concept of "minimum acceptable length" has introduced, which if is used for the pipe segment in pipeline modeling, the seismic response of the pipe around the middle of the segment length will not be affected by the end-conditions. Then the pipeline segment, modeled by beam elements, has been analyzed subjected to transverse waves, assuming different values for the pipe's diameter and thicknesses, and also various kinds of surrounding soil (clay and sand), and the maximum lateral displacement in the pipe segment middle point has been calculated. In the next step, regarding that by using the beam elements the reduced hollow-section area of the pipe is not directly obtainable, the relationship between the maximum compressive strain and the reduced pipe section has been obtained by using shell elements in a series of finite element analyses of a limited part of the pipeline, in which the influence of internal gas pressure has been taken into consideration as well. By this kind of analysis the corresponding strain to the local buckling in the pipe, and also the relation between the reduced hollow-section area in shell element model and the compressive strain in beam element model have been obtained.
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