This study investigated the dynamic behavior of pressurized pipelines under impact loads in various burial environments. A total of 60 tests were conducted using a drop-weight impact testing apparatus, with high-speed cameras and sensors used to collect data throughout the experiments. This approach enabled a thorough investigation of the effects of the soil type, burial depth, and internal pressure on pipeline behavior. The results show that pipeline deformation decreases as burial depth and soil stiffness increase. Under similar conditions, unpressurized pipelines exhibit significantly greater plastic deformation than pressurized pipelines, indicating superior energy absorption. The application of internal pressure leads to a marked increase in the peak impact force compared to scenarios without internal pressure. Fluctuations in internal volume cause pressure variations, affecting the response of the pipeline. Additionally, higher soil stiffness results in increased peak impact force, particularly in loess environments, suggesting that stiffer soils improve pipeline impact resistance. It is important to note that deeper burial does not always lead to reduced impact forces. In stiff soil conditions, greater burial depth may even amplify the impact force. These effects are closely associated with stress concentration under impact loads, changes in soil support capacity, and the influence of internal pressure. The test data and analysis provided in this paper will contribute to optimizing pipeline design and protective strategies, thereby enhancing their safety and reliability.

The understanding of the axial tensile behavior of environmentally corroded pipelines is of great significance for the design, maintenance, and evaluation of such structures. This article presents some experimental data recorded from 210 tensile tests on pipe, which were corroded from grade of 10% to 70% by electrochemical accelerated corrosion method. The fracture modes show that, for the uncorroded pipe, the fracture frequently occurs in the middle of the specimen and then propagates perpendicular to the loading direction. However, for the corroded pipe, the crack’s position, evolution angle, and path have strong randomness. The comparative analysis based on the macroscopic stress‐strain relationship shows that the rapid decrease of the yield stress, ultimate strength, and strain at the fracture for corroded pipe are correlated with the fracture patterns; i.e., the fracture patterns of pipe are changed from uniform to scattered with the continuous increase of the corrosion rate. The reduction factor based on experimental data is recommended for the consideration of the corrosion effect on the tensile strength of the steel pipe. Discussion on the tensile capacity during the service time is also presented.

This paper introduces some experimental data measured from 63 impact tests of pre−stressed strand cables. The test specimens consist of seven steel wires that have a length equivalent to 100 times the outside diameter. To ensure consistency with the engineering service status, the strand cables are fully installed in a specially designed device and are axially pre−stretched to 0% to 40% of the ultimate bearing capacity before being subjected to lateral impact. The mass of the indenter is 50.34 kg, and the maximum impact velocity reaches 13 m/s. Two dimensionless variables, axial force and input kinetic energy, are used to control the experimental parameters. The recorded test data show that input energy and pre−stress level are the key factors governing the impact behavior, which is mainly characterized by plastic deformation controlled by the combination of tension and flexure, and the dynamic fracture concentrated in the impact zone is controlled by the joint effects of compression, tension and shear. As the impact energy increases, the dynamic mode of the test specimen changes from elastic rebound to plastic deformation, and finally evolves into fracture of some or all steel wires, which correspond to slight, partial and total loss of pre−tension, respectively. An increase in the level of pre−stress will significantly reduce the critical displacement of the structural failure but has little effect on the critical failure energy. The present paper provides a basic experimental data and mechanical analysis framework for the analysis, design and evaluation of the mechanical behavior of strands under accidental lateral impact.

This paper describes an experimental study on the pure bending mechanical behavior of a pressurized pipe and adoption of a measured moment‐curvature relationship under different working conditions in numerical simulations for transient pipe‐whip prediction. To describe the effects of pipe contents and internal pressure, the governing equations were derived based on large deformation theory. Bending moment and axial force were uncoupled in the constitutive equation, and an experiment‐based relationship between moment and curvature was adopted. The numerical simulations show that the present model can simulate the mechanical processes of elasticity, plastic hardening, and softening behavior in the initial, middle, and late stages of whole response, respectively. In addition, it was shown that kinks may occur at several positions along an empty cantilever pipe due to the collapse of sections under intense dynamic loading. However, this behavior did not occur for the full pressurized pipe, indicating that the contents and internal pressure are able to effectively impede the partial flattening of the pipe section, improving its critical curvature and changing its plastic dynamic response behavior.

The experimental part in this companion paper revealed that the macroscopic mechanical performance of corroded pipes follows a decreasing trend with the increasing corrosion rate. Inspired by the surface topology by scanning electronic microscopy (SEM) and the scattered distribution of test data, a computational procedure based on the Monte Carlo simulation method was developed in this paper to understand the randomness of the crack propagation process and the performance degradation mechanism of the corroded pipelines. A total of 2700 random samples, which contain three corrosion rates of 15%, 45%, and 70% with each corrosion rate having three variances of 0.02 mm, 0.06 mm, and 0.10 mm, were generated and then were mapped to the shell section of the FE model. In the application of the material model considering the damage, a series of “numerical” tensile experiments were carried out. The simulation analysis indicated that the corrosion rate and the standard variance of the thickness collaboratively dominated the mechanical performance of the corroded specimen. Under the same standard deviation, the wall corresponding to the higher corrosion rate is more likely to cause stress concentration in the weak position, which makes the pipe more prone to fail. Furthermore, under the same corrosion rate, the increase of the standard deviation will aggravate the unevenness of the wall thickness distribution, and then the lower tensile load will cause damage at weak locations and lead to randomness of the crack propagation path, thereby reducing the pipe’s macroscopic strength and fracture strain. The analytical methods in this paper have the potential of being a useful tool for structural reliability assessments of aged pipelines and the full life cycle design of new pipeline networks.