The behavior of horizontally bent buried pipes along faults slip with numerical and experimental modelling

Considering the high importance of energy-carrying buried pipelines in lifeline network, it is vital to understand this kind of structures against seismic dynamic excitations. In this paper, seismic behavior in some part of a buried pipe with horizontal bend under Bam earthquake record effect (2003, Iran) is studied experimentally and numerically using ABAQUS software. In the numerical model, the pipe is modelled via a three-dimensional four-node shell system, and the soil is modeled using elastoplastic properties.As non-linear dynamic analysis, with applying Bam earthquake record effects, a thorough parametric studied are performed on different pipe diameter and thicknesses, and then the axial strain and plastic strain values obtained from the strain gauges along the horizontally-bent pipe are compared with the numerical model results.Also, a correlation is obtained which relates the location of plastic hinge formation point on the pipe to the pipe diameter and thickness. The comparison of numerical model and experimental results show that in buried horizontally-bent pipes, the most axial strain, plastic strain, and stress in the pipe take place in the fixed wedge and near to the fault line. In the buried horizontally-bent pipes, with increasing the pipe diameter to thickness ratio this location will get more distance from the fault line.Also, the pipelines with larger diameters have lower pipe-soil strain ratio (εp/s) values causing lower axial and plastic strains.