Abstract
Buried pipelines serve as a critical component of lifeline systems, such as water and gas supply. They are interconnected to form a network to transport utilities. The connections change the geometry and stiffness of pipelines and impact the seismic response of the pipelines. This paper investigates the influence of connections on the seismic response of buried continuous steel trunk lines. A finite element model is introduced for analyzing the seismic response of buried pipeline networks. The seismic response of continuous steel pipelines with different connections, including cruciform and T‐, K‐, L‐, and Y‐shaped, is analyzed. The impact of site class, pipe diameter, branch angle, and angle of wave incidence on the response of pipe connections is explored. An influence coefficient defined to characterize the strain amplification at the connections is proposed for different forms of connections. Engineering measures to reduce the strain amplification at connections are suggested.
Highlights
Buried pipelines can be damaged by permanent ground deformation (PGD) linked to irrecoverable ground movement generated by faulting, liquefaction, and landslide and transient ground deformation (TGD) due to wave propagation effects. e PGD generates localized severe damage to buried pipelines, while the TGD typically affects the buried pipe network in a large area. is paper focuses on the TGD effects of earthquake damage. e TGD damage to buried pipelines has attracted extensive attention in academia
Studies developed analytical models to estimate the deformation of underground pipelines using pseudostatic methods. e seismic waves were assumed as travelling waves, and the pipelines were assumed to deform together with the ground [5]
E.g., finite element (FE) methods, were widely used to simulate soilstructure interaction. e pipelines were modeled as elastic beams connected with soil springs [6, 7] or shell elements buried in soil continuum [8, 9], and the dynamic response of the pipelines was analyzed [10, 11]
Summary
FE Model of Seismic Response of Buried Pipe Network. E axial and lateral motions of a buried pipeline during earthquakes are expressed as z2u(x, t) EA zx2 − kAu(x, t) −kAug(x, t),. Solving the pipe network system stiffness equation, the displacement of the pipeline elements can be derived. E coordinates at the middle point of each element are projected to the propagation direction of the wave and the ground motion in input at this point (Figure 5) such that the ground motion time history of all pipeline elements in the network can be obtained. E seismic response of the pipe network can be calculated by solving the system equation For far-field analysis, the wave surface can be simplified as a plane perpendicular to the propagation direction. e coordinates at the middle point of each element are projected to the propagation direction of the wave and the ground motion in input at this point (Figure 5) such that the ground motion time history of all pipeline elements in the network can be obtained. e ground motion is decomposed along the x- and y-directions, respectively. e input wave is a shear wave (S-wave) with the amplitude along x-axis as fx(t) f(t)cos θ and y-axis as fy(t) f(t)sin θ. e seismic response of the pipe network can be calculated by solving the system equation
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