Abstract
Validated 3D solid finite element (FE) models offer an accurate performance of buried pipelines at earthquake faults. However, it is common to use a beam–spring model for the design of buried pipelines, and all the design guidelines are fitted to this modeling approach. Therefore, this study has focused on (1) the improvement of modeling techniques in the beam–spring FE modeling approach for the reproduction of the realistic performance of buried pipelines, and (2) the determination of an appropriate damage criterion for buried pipelines in beam–spring FE models. For this paper, after the verification of FE models by pull-out and lateral sliding tests, buried pipeline performance was evaluated at a strike-slip fault crossing using nonlinear beam–spring FE models and nonlinear 3D solid FE models. Material nonlinearity, contact nonlinearity, and geometrical nonlinearity effects were considered in all analyses. Based on the results, pressure and shear forces caused by fault movement and pipeline deformation around the high curvature zone cause local confinement of the soil, and soil stiffness around the high curvature zone locally increases. This increases the soil–pipe interaction forces on pipelines in high curvature zones. The beam–spring models and design guidelines, because of the uniform assumption of the soil spring stiffness along the pipe, do not consider this phenomenon. Therefore, to prevent the underestimation of forces on the pipeline, it is recommended to consider local increases in soil spring stiffness around the high curvature zone in beam–spring models. Moreover, drastic increases in the strain responses of the pipeline in the beam–spring model is a good criterion for a damage evaluation of the pipeline.
Highlights
The pipeline network has been spread all over the world to provide the essential needs of human societies
The 3D solid and beam–spring finite element (FE) models were analyzed with six cases with 60◦ strike-slip fault displacements of (δ) 0.17D, 0.5D, 1D, 2D, 3D, and 4D, where D is the pipe diameter
The local stiffening of the soil in the 3D solid model is due to the local confinement of the soil at the fault line during the strike-slip fault movement
Summary
The pipeline network has been spread all over the world to provide the essential needs of human societies (e.g., for transmission of gas, water, oil, wastewater, and chemical products). There are a great deal of pipelines crossing seismic hazardous areas, such as high curvature zones [1]. Earthquakes are the greatest threat to structures [2]. In the case of buried pipelines, most damage arises due to permanent ground deformation (PDG), for example, fault dislocations, liquefaction, and landslides. Small regions within the pipeline network and earthquake fault zones are prone to PGD; because they cause large deformation of the pipelines, the damage potential is very high. There are very few pipeline cases that are damaged by wave propagations [3,4]
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