Academic literature on the topic 'Non-displacement pile under axial load'
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Journal articles on the topic "Non-displacement pile under axial load"
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Xu, Hong-Fa, Ji-Xiang Zhang, Xin Liu, Han-Sheng Geng, Ke-Liang Li, and Yin-Hao Yang. "Analytical Model and Back-Analysis for Pile-Soil System Behavior under Axial Loading." Mathematical Problems in Engineering 2020 (March 19, 2020): 1–15. http://dx.doi.org/10.1155/2020/1369348.
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The interaction mechanism between piles and soils is very complicated. The load transfer function is generally nonlinear and is affected by factors such as pile side roughness, soil characteristics, section depth, and displacement. Therefore, it is difficult to solve the pile-soil system based on load transfer function. This paper presents a new method to study the soil-pile interaction problem with respect to axial loads. First, the shapes of the axial force-displacement curves at different depths and the displacement distribution curves along pile axis at different pile-top displacements were analyzed. A simple exponential function was taken as relationship model to express the relationship curves between two distribution functions of axial force and displacement along pile shaft obtained by using the geometric drawing method. Second, a new analytical model of the pile-soil system was established based on the basic differential equations for pile-soil load transfer theory and the relationship model and was used to derive the mathematical expressions on the distribution functions of the axial force, the lateral friction, and the displacement along pile shaft and the load transfer function of pile-side. We wrote the MATLAB program for the analytical model to analyze the influence laws of the parameters u and m on the pile-soil system characteristics. Third, the back-analysis method and steps of the pile-soil system characteristics were proposed according to the analytical model. The back-analysis results were in good agreement with the experimental results for the examples. The analysis model provides an effective way for the accurate design of piles under axial loading.
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Richwien, W., and Z. Wang. "Displacement of a pile under axial load." Géotechnique 49, no. 4 (August 1999): 537–41. http://dx.doi.org/10.1680/geot.1999.49.4.537.
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Meyerhof, G. G., and V. V. R. N. Sastry. "Bearing capacity of rigid piles under eccentric and inclined loads." Canadian Geotechnical Journal 22, no. 3 (August 1, 1985): 267–76. http://dx.doi.org/10.1139/t85-040.
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The ultimate bearing capacity of instrumented vertical single rigid model piles in homogeneous loose sand and soft clay under vertical eccentric and central inclined loads has been investigated. The results of these load tests provide a more realistic lateral soil pressure distribution on the pile shaft and better theoretical estimates of pile capacity under pure moment and under horizontal load. For intermediate eccentricities and inclinations of the load, the bearing capacity can be obtained from simple interaction relationships between the axial load and moment capacities and between the axial and horizontal load capacities, respectively. The influence of lateral soil pressures due to installation of displacement piles in clay is examined in relation to the ultimate load of the pile. The analyses are compared with the results of model tests and some field case records. Key words: bearing capacity, clay, eccentric loading, horizontal load, instrumentation, model test, pile, sand.
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Cai, Yan-yan, Bing-xiong Tu, Jin Yu, Yao-liang Zhu, and Jian-feng Zhou. "Numerical Simulation Study on Lateral Displacement of Pile Foundation and Construction Process under Stacking Loads." Complexity 2018 (2018): 1–17. http://dx.doi.org/10.1155/2018/2128383.
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Lateral displacement of pile foundation is crucial to the safety of an overall structure. In this study, a numerical simulation on the lateral displacement of pile foundation under stacking loads was conducted to determine its relation with different influencing factors. Simulation results demonstrated that stacking loads at the pile side mostly influence the lateral displacement of pile foundation. The lateral displacement of pile foundation increases by one order of magnitude when the stacking loads increase from 100 kPa to 300 kPa. Other influencing factors are less important than stacking loads. Lateral displacements of the pile body and at the pile top can be reduced effectively by increasing the deformation modulus of surface soil mass, reducing the thickness of soft soil, and expanding pile diameter. Our analysis indicates that a nonlinear relationship exists between the lateral displacement at the pile top and the pile diameter. The lateral resistance of the pile body can be enhanced by coupling the stacking load along piles and the axial force at the pile top. An actual large-scale engineering project was chosen to simulate the effects of postconstructed embankment on lateral displacement and axial force of bridge pile foundation under different construction conditions and to obtain the lateral displacement of the pile body and the negative frictional resistance caused by soft soil compression under stacking loads. On the basis of the calculated results, engineering safety and stability were evaluated, and a guide for the design and construction was proposed.
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Ma, Tianzhong, Yanpeng Zhu, Xiaohui Yang, and Yongqiang Ling. "Bearing Characteristics of Composite Pile Group Foundations with Long and Short Piles under Lateral Loading in Loess Areas." Mathematical Problems in Engineering 2018 (November 12, 2018): 1–17. http://dx.doi.org/10.1155/2018/8145356.
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It is very necessary to research the bearing characteristics of composite pile group foundations with long and short piles under lateral load in loess areas, because these foundations are used widely. But few people researched this problem in loess areas up to now worldwide. In this paper, firstly, an indoor test model of a composite pile foundation with long and short piles is designed and then employed to explore the vertical load bearing characteristics and load transfer mechanisms of a single pile, a four-pile group, and a nine-pile group under different lateral loads. Secondly, ANSYS software is employed to analyze the load-bearing characteristics of the test model, and for comparison with the experimental results. The results demonstrate the following. (1) The lateral force versus pile head displacement curves of the pile foundation exhibit an obvious steep drop in section, which is a typical feature of piercing damage. A horizontal displacement limit of the pile foundation is 10 mm and 6mm for the ones sensitive to horizontal displacement. (2) The axial force along a pile and frictional resistance do not coincide, due to significant variations and discontinuities in the collapsibility of loess; a pile body exhibits multiple neutral points. Therefore, composite pile groups including both long and short piles could potentially maximize the bearing capacity and reduce pile settlement. (3) The distribution of stress and strain along the pile length is mainly concentrated from the pile head to a depth of about 1/3 of the pile length. If the lateral load is too large, short piles undergo rotation about their longitudinal axis and long piles undergo flexural deformation. Therefore, the lateral bearing capacity mainly relies on the strength of the soil at the interface with the pile or the horizontal displacement of the pile head.
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Qiu, Hong Zhi, Ji Ming Kong, and Yin Zhang. "Analysis on Dynamic Response of the Foundation Pit Supporting Structure under Vehicle Loads." Advanced Materials Research 790 (September 2013): 638–42. http://dx.doi.org/10.4028/www.scientific.net/amr.790.638.
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Using ABAQUS software analyzed the dynamic response of foundation pit supporting structure under vehicle loads. The vehicle load was simplified as a half-wave sinusoidal load, in order to analyze the influence of internal force and displacement of pile-anchor supporting structure under the vehicle loads, the position of half-wave sinusoidal load and the size of radian frequency were considered. Loading location away from the supporting structure is more nearly and the displacement value of support piles is greater, the greater the axial force of the bolt; with the increasing of radian frequency, the horizontal displacement value of supporting piles increased, on the contrary, the axial force of bolt reduced. A practical engineering was studied here. analysis of the monitoring data and compared with the numerical results, the analysis showed that the experimental results and numerical results are in good agreement, and the numerical method can be used as an effective means of research. The conclusion of the study has significance on engineering practice.
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Chen, Chi, Long Zou, and Hong Bo Shen. "Axial Force Analysis of the Single Pile Based on FLAC3D." Advanced Materials Research 790 (September 2013): 418–21. http://dx.doi.org/10.4028/www.scientific.net/amr.790.418.
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Complex interaction mechanism of pile and soil, pile load transfer analysis is difficult. On the basis of analyzing the load transfer mechanism of the friction pile, using the FLAC3D analysis on the initial ground stress state of equilibrium , axial load under the action of pile axial force and displacement, got the ultimate load bearing capacity of single pile and the stress of the contact surface. Analysis results show that the load and displacement in a certain stage into a proportional relationship. Also shows that simulation is feasible and provide a reliable method for the analysis of pile groups.
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El Naggar, M. Hesham, and Jin Qi Wei. "Axial capacity of tapered piles established from model tests." Canadian Geotechnical Journal 36, no. 6 (December 1, 1999): 1185–94. http://dx.doi.org/10.1139/t99-076.
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Tapered piles represent a more efficient distribution of pile material than uniform cross section piles in several respects. An extensive experimental research program was conducted to study the efficiency of tapered piles compared with piles of uniform cross section with the same material input. Three instrumented model steel piles with different degrees of taper were used in this program. The piles were tested in a large-scale laboratory setup under compressive and tensile loads. The pile head load and displacement and the strain along the piles were measured simultaneously. The objectives of the present paper were twofold: to examine the validity of the experimental results, and to use the unit load transfer curves established from the experimental results to predict the bearing capacity of prototype tapered piles. The shaft resistance for straight-sided wall piles established from the experimental results compared well with the theoretical predictions using the standard design procedure. The beneficial effect of pile taper was significant up to a depth of 20 pile diameters. The negative effect of the pile taper on the uplift capacity diminished quickly with depth and hence the performance of actual tapered piles (with greater length) would be comparable to that of straight-sided wall piles.
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Karkush, M. O. "Impacts of Soil Contamination on the Response of Piles Foundation under a Combination of Loading." Engineering, Technology & Applied Science Research 6, no. 1 (February 5, 2016): 917–22. http://dx.doi.org/10.48084/etasr.616.
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The behavior of single piles driven into contaminated clayey soil samples subjected to a combination of static axial and cyclic lateral loadings have been studied in this research. A laboratory model was manufactured especially for studying such behavior. A solid circular cross sectional area pile of diameter 19 mm and made from aluminum, the pile was embedded into the soil with an eccentricity to embedded length (e/L) ratio of 0.334. The intact soil samples and industrial wastewater were obtained from the center of Iraq. The industrial wastewater is a byproduct disposed from Musayib thermal electric power plant. The intact clayey soil samples were synthetically contaminated with four percentages of 10, 20, 40 and 100% from the weight of water used in the soaking process which continued for a period of 30 days. The different percentages of contaminant concentrations have significant effects on the lateral load-displacement relation of the piles subjected to a combination of axial and lateral loadings. The vertical displacement under the same vertical load increased by 5–95%, the axial strength of piles decreased by 10–34% and the lateral-bearing capacity of the piles decreased by 10–34% with increasing the percentage of contamination from 10 to 100%. The ratio of permanent lateral displacement to the total lateral displacement was increased by 23–27% when the concentration of contaminant increased by 10-100%. Generally, the application of axial loading increases the lateral-bearing capacity of piles, and reduces the total lateral displacement.
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Chen, Xing Chong, Xue Lin Yue, and Yong Liang Zhang. "Research on Method of Non-Linear Static Pushover Analysis and Influential Mechanism of Displacement Ductility of Single Pile." Applied Mechanics and Materials 204-208 (October 2012): 990–94. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.990.
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In this article, the distribution of plastic hinge model is adopted to simulate the elastic and plastic of pile body, p-y curve is used to simulate resistance of pile foundation soil. We do static non-linear pushover analysis of the single pile of pile foundations, and research the influence of the axial compressive ratio η of pile shaft, longitudinal reinforcement rate ρ of section, stirrup ratio µof section and shear strength C of foundation soil to the system-interaction of pile and soil. The result shows that axial compressive ratio of pile shaft has a significant influence on horizontal limit bearing capacity and the displacement ductility of the system. With the increase of the axial compressive ratio, system of the displacement ductility reduces gradually, but the limit bearing capacity increases gradually. Under a horizontal load, the order and the mechanism of plastic hinge are obviously different because of different axial compressive ratio of pile shaft，This analysis method may further provide a reference for nonlinear seismic analysis of pile bents.
Dissertations / Theses on the topic "Non-displacement pile under axial load"
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Camões, Lourenço João. "Numerical Modelling of Non-Displacement Piles in Sand : The importance of the dilatancy in the resistance mobilization." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASC033.
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Cette thèse se concentre sur la réponse des pieux installés dans le sable lorsqu'ils sont soumis à des actions verticales et en particulier concernant la pertinence du comportement volumétrique du sol sur cette réponse. À l'interface sol-pile, lorsque le sol est déformé par cisaillement, des déformations volumétriques (généralement dilatation) se produisent, ce qui provoque une importante variation de l'état de contrainte. Cela se fait à l'aide de modèles numériques par éléments finis en adoptant le modèle élastoplastique ECP, une loi constitutive réaliste pour décrire le comportement du sol dans le massif et celui se trouvant dans la zone où les déformations se localizent à l'interface sol-pieu. Ce modèle, formulé en contraintes effectives, est un modèle multiméchanismes qui tient compte des facteurs importants qui influencent le comportement du sol, comme l'élasticité non linéaire, la plasticité incrémentale ou la description de l'état critique. D'autres aspects importants, comme la distinction entre comportement dilatant et contractant, la définition de lois de flux ou distinction entre des différents états de compacité peuvent être considérés via les paramètres du modèle. Ce n'est qu'avec un modèle rhéologique avancé, capable de capturer le comportement réel du sol, qu'il sera possible de modéliser l'interaction sol-pieuThis thesis' focus is the response of non-displacement piles installed in sand when subjected to axial load, specifically in the relevance of soil's volumetric behavior on this response. At the soil-pile interface, when the soil is distorted by shear volumetric deformations (usually dilatation) occur, which causes a significant variation in the stress state. That is done with the support of finite element numerical models by adopting the elastoplastic ECP model, a realistic constitutive law for the soil and the soil-pile interface. This model, written in terms of effective stresses, is a multimechanisms model that takes into account important factors that influence soil behaviour, such as non-linear elasticity, incremental plasticity or the critical state definition. Other important aspects, such as the distinction between dilating or contractive behaviour, flow rule or density index, can be considered via the model parameters. Only with an advanced soil model, that captures the real behaviour of the soil, it is possible to model the involved phenomena
Conference papers on the topic "Non-displacement pile under axial load"
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Joglekar, Manish M., S. G. Joshi, and B. K. Dutta. "Fracture Mechanics Study of Cracked Pipe Bends Under Internal Pressure and Bending Moments." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95263.
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The present work attempts to investigate some aspects of the fracture behavior of cracked pipe bends under the action of in-plane bending moments, with and without internal pressure. The results of the elastic-plastic FE analysis of the defect free elbow under the action of in-plane opening and closing bending moments are presented with the emphasis on the hoop and axial stress distribution at various salient locations in the elbow. A severity matrix is outlined subsequently, correlating the various possible cracked configurations and the loading patterns. Parametric studies on the cracked elbows are carried out, in which the parameters, such as ratio of crack depth to elbow thickness (a/t), angle of the part-through wall crack, bend factor ‘h’ and the internal pressure ‘P’ are varied. The variations of the J-integral versus load and load versus load line displacement are presented. The crack initiation load is determined from the material specific critical value of the J-integral. A non-dimensional parameter is suggested as ratio of plastic collapse load to the crack initiation load, which increases with the increase in the internal pressure both in case of the throughwall flawed elbow as well as in the part-throughwall flawed elbow.
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Je, Jin-Ho, Kuk-Hee Lee, Yun-Jae Kim, and Young-Ryun Oh. "C(t) Estimation of Cracked Pipe Under Radial Thermal Gradient or Axial Displacement Control Load." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63435.
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The present study analyzes the elastic follow-up factor under various secondary loads in the piping with cracks through finite element analysis. The secondary loads being considered included axial tensile load caused by the displacement applied in form of uniform stress through thickness and the load due to the thermal gradient in the radial direction applied as bending stress. According to this study, under displacement control loads, elastic follow-up factor can increase greatly.
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Suzuki, Ryosuke, Masaaki Matsubara, Kento Arai, Kosuke Takano, and Tsukasa Hagiwara. "Estimation of Stress-Displacement Curve of Multiple Notched Stainless Steel Pipe Under Combined Load of Axial Force and Bending." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84523.
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Integrity evaluation of stainless steel piping with multiple flaws under combined load is difficult when one flaw is located near other flaw. This is because that the stress state in the piping becomes complicated as a result of the mutual interference of the stress fields occurred by flaws. If the stress-displacement curve of stainless steel piping with two flaws can be estimated by using the curves of single notched stainless steel piping before and after flaw coalescence, the integrity evaluation of stainless steel piping with two flaws becomes easy and simple. In this study, the stress-displacement curves of the single notched pipes with notch angle 37° or 90° subjected to combined tensile and bending loads are obtained experimentally. In addition, the stress-displacement curve of the pipe which has two notches in the same cross section area and both notch angles are 37° and notch interval 16° (total notch angle is 90°) is also obtained experimentally. The stress-displacement curve of the 37°+37° multiple notched pipe is compared with the curves of the 37° single notched pipe and the 90° single notched pipe. In the tensile principal tests, the stress-displacement curve of the 37°+37° notched pipe shows good agreement with the curve of the 37° notched pipe until notch coalescence. In the bending principal test, the error of the stress-displacement curves between the 37° +37° notched pipe and the 37° notched pipe is higher than that of the tensile principal test. The stress-displacement curve of the 37° +37° notched pipe after notch coalescence shows relatively good agreement with the curve of the 90° notched pipe in the bending principal test. After notch coalescence, the error of the stress-displacement curves of the 37° +37° notched pipe and 90° notched pipe for tensile principal test is higher than that for the bending principal test.
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Sa´nchez Sa´nchez, He´ctor A., and Carlos Corte´s Salas. "Deformation of Steel Straight Pipes With Internal Pressure Under Axial Compression and Bending Load by Seismic Action." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57491.
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Due to the high risk seismic in many zones of Mexico it has been observed that the ground motions often show large horizontal displacement. This displacement causes large deformations of buried pipelines. Then, the knowledge of study and design recommendations related to deformability of the pipes has not been sufficiently provided. A grand number of studies have been reported concerned about the plastic deformations or buckling of the straight pipe. Most of them are performance of column pipe without internal pressure. Therefore, in this work are analyzed the steel straight pipes, for the purpose of clarifying the deformations of the pipes with internal pressure under large displacement and bending. Effect of internal pressure on deformability of pipe is investigated both under load bending. Stress analysis using FEM is performed in order to simulate the large deformations of the pipes.
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Sun, Jason, Han Shi, and Paul Jukes. "Upheaval Buckling Analysis of Partially Buried Pipeline Subjected to High Pressure and High Temperature." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49498.
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Offshore industry is now pushing into the deepwater and starting to face the much higher energy reservoir with high pressure and high temperature. Besides the significant impacts on the material, strength, and reliability of the wellhead, tree, and manifold valve; high Pressure (HP) also leads to thicker pipe wall that increases manufacturing and installation cost. High Temperature (HT) can have much wider impact on operation since the whole subsea system has to be operated over a greater temperature range between the non-producing situations such as installation, and long term shut down, and the maximum production flow. It is more concerned for fact that thicker wall pipe results in much greater thermal load so to make the pipeline strength and tie-in designs more challenging. Burying sections of a HPHT pipeline can provide the advantages of thermal insulation by using the soil cover to retain the cool-down time. Burial can also help to achieve high confidence anchoring and additional resistance to the pipeline axial expansion and walking. Upheaval buckling is a major concern for the buried pipelines because it can generate a high level of strain when happens. Excessive yielding can cause the pipeline to fail prematurely. Partial burial can have less concern although it may complicate the pipeline global buckling behavior and impose challenges on the design and analysis. This paper presents the studies on the upheaval buckling of partially buried pipelines, typical example of an annulus flooded pipe-in-pipe (PIP) configuration. The full-scale FE models were created to simulate the pipeline thermal expansion / upheaval / lateral buckling responses. The pipe-soil interaction (PSI) elements were utilized to model the relationship between the soil resistance (force) and the pipe displacement for the buried sections. The effects of soil cover height, vertical prop size, and soil resistance on the upheaval and lateral buckling response of a partially buried pipeline were investigated. This paper presents the latest techniques, allows an understanding in the global buckling, upheaval or lateral, of partially buried pipeline under the HPHT, and assists the industry to pursue safer but cost effective design.
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Cakiroglu, Celal, Amin Komeili, Samer Adeeb, J. J. Roger Cheng, and Millan Sen. "Numerical Analysis of High Pressure Cold Bend Pipe to Investigate the Behaviour of Tension Side Fracture." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90381.
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The cold bend pipelines may be affected by the geotechnical movements due to unstable slopes, soil type and seismic activities. An extensive experimental study was conducted by Sen et al. in 2006 to understand the buckling behaviour of cold bend pipes. In their experiments, it was noted that one high pressure X65 pipe specimen failed under axial and bending loads due to pipe body tensile side fracture which occurred after the development of a wrinkle. The behaviour of this cold bend pipe specimen under bending load has been investigated numerically to understand the conditions leading to pipe body tension side fracture following the compression side buckling. Bending load has been applied on a finite element model of the cold bend by increasing the curvature of it according to the experimental studies conducted by Sen [1]. The bending loads have been applied on the model with and without internal pressure. The distribution of the plastic strains and von Mises stresses as well as the load–displacement response of the pipe have been compared for both load cases. In this way the experimental results obtained by Sen [1] have been verified. The visualization of the finite element analysis results showed that pipe body failure at the tension side of the cold bend takes place under equal bending loads only in case of combined loading with internal pressure.
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Wang, Jianhua, and Yifei Fan. "Centrifuge Model Tests on Effects of Spudcan Penetration on Adjacent Loaded Piles." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19304.
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Abstract It is very important for designers of offshore platforms to understand affecting mechanism of mobile jack-up spudcan penetration and extraction on adjacent loaded piles. Existing centrifuge model tests are on effects of spudcan penetration on adjacent unloaded piles. In engineering, offshore platform piles are subjected to lateral and vertical pile head loads before spudcan penetration. In order to understand affecting mechanism of spudcan penetration on adjacent loaded piles, centrifuge model tests were conducted under 50g condition. Model test strata are the saturated soft clay and the fine sand and the model pile head constraint is free. Spudcan penetration resistances, lateral earth pressures along pile shaft, lateral pile deflection, vertical pile displacement, bending moments and axial forces along pile shaft are measured during spudcan penetration and after extraction. Effects of spudcan penetration on the pile-soil interaction p-y relationship and the bearing capacity of piles are analyzed based on model test results. Results show that the lateral soil resistance affected by spudcan penetration decreases due to soil movement. The lateral deflection of loaded pile obviously increases, the side frictional resistance decreases and the end resistance increases during spudcan penetration. The spudcan penetration-induced incremental pile response does not disappear after spudcan extraction. These results are helpful for understanding the effect mechanism of spudcan penetration and extraction on adjacent loaded piles.
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Zhang, Lei, Kaiming Lin, Yang Fu, and Bingjun Gao. "CCG of PE100 and Life Prediction of PE Pipe With Axial Semi-Elliptical Crack." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93556.
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Abstract High density polyethylene (HDPE) is widely used in city water and gas piping system and even in nuclear engineering for its excellent properties in flexibility, impact resistance, aging and corrosion resistance, reliable connection, long service life. It is generally believed that the typical failure mode of PE pipe under long-term static pressure load is the slow crack growth (SCG) caused by creep crack initiation (CCI) and creep crack growth (CCG), which is a kind of quasi-brittle failure. Scratching often occurs during PE pipe installation due to the drag of pipe without any protection, which would leave axial cracks as the initial defect. This would harm the long term performance of pressurized HDPE pipe. In the present work, the creep crack kinetics was experimentally determined in term of C* integral, and then CCG behavior of PE pipe with axial semi-elliptical crack was discussed. With the help of a CARE electronic universal testing machine and DIC displacement measuring system, creep tests are performed with smooth bar specimen of PE100 pipe parent material. And the stationary creep law parameters were determined. The crack opening displacement (COD) rates were determined by creep cracking test with cracked round bar specimen. With the help of compliance calibration tests, the COD curves were changed into crack propagation curves and the creep crack kinetics was eventually determined in term of C* integral. By assuming an semi-elliptical crack front with nearly the same C* integral, the creep crack propagation was predicted with the determined crack kinetics. And the allowable initial crack size was also determined for the PE pipe discussed. Compared with that determined in terms of SIF, current study yields much margin for the allowable initial crack.
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Chatziioannou, Konstantinos, Yuner Huang, and Spyros A. Karamanos. "Dented Externally-Pressurised Pipes Subjected to Cyclic Axial Loading." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95814.
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Abstract The present paper describes a numerical investigation of the mechanical response of externally-pressurized dented stainless-steel pipes, subjected to reverse cyclic axial loading. This is the first part of a large-scale project, between The University of Edinburgh and Tianjin University, and is motivated by the mechanical response of offshore pipelines, which are often subjected to cyclic loading during installation or operation. Under those cyclic loading conditions, the pipe may collapse because of accumulation of plastic deformations at the dent area. The paper describes a numerical simulation of the above physical problem, in an attempt to support experiments on 50mm-diameter stainless steel pipes, which are being performed at the laboratory facilities of Tianjin University. Pipe segments are subjected to reverse cyclic axial loading (tension and compression), in the presence of external pressure. Prior to the application of external pressure and axial load, the pipes are locally dented, in the form of “smooth dent” or “local ovalization”, so that collapse initiates at the dent area. The numerical simulation is aimed at examining some aspects of pipeline behavior to support and complement the experimental observations. The simulation is conducted using rigorous finite element tools, which account for large displacement and nonlinear material. Towards this purpose, an advanced material model is employed, capable of describing the phenomenological aspects of material response under cyclic loading, such as the accumulation of plastic strain and ratcheting. In the first part of the analysis, the local ovalization (denting) process is simulated. Subsequently, the pipes are subjected to uniform constant external pressure and, keeping the pressure level constant, monotonic or cyclic axial loading is applied until collapse. The numerical results are aimed at identifying the interrelation between the magnitude of the applied loading and the number of loading cycles to failure. The results are presented in diagrams of axial displacement, ovalization and local strain versus the corresponding number of cycles to failure, for specific levels of external pressure.
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Liu, Xiaoben, Hong Zhang, Mengying Xia, Jianping Liu, and Qian Zheng. "An Improved Analytical Strain Analysis Method for Buried Steel Pipelines Subjected to Abrupt Permanent Ground Displacement." In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9341.
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Abstract Abrupt permanent ground displacement is a typical loading condition for pipelines crossing geotechnical hazard areas. An improved analytical method for calculating longitudinal strain of buried pipeline under tension combined with bending load induced by permanent ground displacement (PGD) was proposed, in which, the pipe steel was considered as a bilinear material and the soil constraint on pipe was considered as a series of elastic-plastic nonlinear soil springs. Effects of elastic deformation of axial soil springs on pipe strain was derived accurately. Effects of axial force in pipe on pipe’s bending deformation was considered directly in the governing equation of pipe. Equilibrium between the section stresses in the large deformed pipe sections near fault trace and the section force and moment at the same position derived by the beam theory was used to obtain the nonlinear stress distributions in the pipe section and furtherly to obtain the equivalent modulus describing the locally decreased pipe stiffness. This method makes it possible to accurately derive the pipe longitudinal strain considering the effects of pipe material nonlinearity induced locally decreased pipe stiffness in large bending deformed pipe segments. A three dimensional nonlinear finite element model was also established by general software package ABAQUS to serve as a benchmark to validate the accuracy of proposed analytical method. Shell and pipe elements were employed to simulate pipes in large deformation and small deformation regions respectively. Distributed nonlinear soil spring elements were employed to simulate nonlinear soil constraints on pipe. Various loading conditions were performed to compare the efficiency and accuracy of the proposed analytical method comparing with the FE method. Results show the proposed analytical method can predict accurate longitudinal strain results even large plastic deformation appears in pipe. And comparing with FE method, analytical method has advantages in calculating efficiency, which is more suitable for application in engineering practice.