Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Failure Modes ◽  
Bending Strength ◽  
Metal Loss ◽  
Pipe Surface ◽  
Comparison Results ◽  
Mechanical Interference ◽  
Bending Capacity

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage after mechanical interference. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe tests. Artificial damage, such as a dent, metal loss, a crack, and combinations thereof, is introduced to the pipe surface in advance. Four-point bending tests are performed to investigate the structural behavior of metallic pipes in terms of bending moment–curvature diagrams, failure modes, bending capacity, and critical bending curvatures. Test results show that the occurrence of structural damage on the pipe compression side reduces the bending capacity significantly. Only a slight effect has been observed for pipes with damage on the tensile side as long as no fracture failure appears. The possible causes that have introduced experimental errors are presented and discussed. The test data obtained in this paper can be used to further quantify damage effects on bending capacity of seamless pipes with similar D/t ratios. The comparison results in this paper can facilitate the structural integrity design as well as the maintenance of damaged pipes when mechanical interference happens during the service life of pipelines.

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2017 ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Bending Strength ◽  
Bending Moment ◽  
Tensile Tests ◽  
Metal Loss ◽  
Outer Diameter ◽  
Pipe Surface ◽  
Ultimate Bending Strength

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe specimens. Artificial damage such as dent, metal loss, crack and combinations thereof is introduced on the pipe surface in advance. The entire test project consists of 34 seamless pipes with a relative low Diameter-to-thickness (D/t) ratio around 21.3, among which four intact specimens and thirty damaged specimens have been carried out for mutual comparison. Extensive measurements on structural damage and pipe geometries including wall thickness and outer diameter are performed. The material properties are measured by tensile tests with specimens from both pipe longitudinal and hoop direction. The four-point bending tests are performed to investigate the structural behaviors of metallic pipes. The bending strength associating with failure mode of each specimen is documented extensively, and the bending moment-curvature curves are presented and discussed. The fundamental research of experiments on damaged pipes in the present paper will be deployed for the following numerical and analytical research in the near future.

Limit States for Deepwater Flowlines and Risers: Review of the Research Activities at the Submarine Technology Laboratory/COPPE

2003 ◽  
Author(s):  
S. F. Estefen ◽  
T. A. Netto ◽  
I. P. Pasqualino
Keyword(s):  
Ultimate Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Experimental Tests ◽  
Limit States ◽  
Collapse Pressure ◽  
Research Activities ◽  
Structural Resistance ◽  
Buckle Arrestors

Research activities related to the limit states of flowlines and risers conducted at the Submarine Technology Laboratory / COPPE in cooperation with PETROBRAS are presented. The motivation for most of the research programs is associated with deepwater challenges arising from the rigid pipe installations at Campos Basin. Initially ultimate strength of intact pipes are investigated together with aspects related to residual strength, buckling propagation and buckle arrestors. Based on the experimental results numerical models have been correlated in order to be used to generate results for full scale steel pipes. Ultimate strength curves have been then produced as well as the analytical equation representative of these curves. Experimental tests of buckling propagation for small and large scale pipes have also been performed to obtain the bias factor for different equations proposed in the literature. Based on this study an equation for propagation pressure has been recommended. In addition, ring and cylinder buckle arrestors have been tested in order to propose an expression relating crossing over pressure with the arrestor geometries. An overview of the studies aiming at establishing the influence of the reeling method of installation on the failure modes of flowlines and steel catenary risers is presented. It is emphasized the influence of cross-section ovality and weld defect amplification due to plastic bending on collapse pressure and fatigue life, respectively. Finally, the development of a new concept of sandwich pipe for ultra deepwater, combining structural resistance and thermal insulation is discussed.

Root Cause Analysis of Dent With Crack: A Case Study

2012 ◽  
Author(s):  
Udayasankar Arumugam ◽  
Ming Gao ◽  
Ravi Krishnamurthy ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Failure Modes ◽  
Fatigue Testing ◽  
Strain Analysis ◽  
Ductile Failure ◽  
Field Investigation ◽  
Primary Objective ◽  
Metal Loss ◽  
Pipe Surface ◽  
Strain Limit

A combined caliper and tri-axial MFL in-line inspection (ILI) reported a bottom side 2.7%OD dent associated with 76% metal loss. The reported dent depth is well below the 6% limit while strain analysis of this ILI dent profile showed a maximum equivalent strain of 17.4%, which exceeds the 6% strain limit for gas pipeline. Due to the high dent strain level, the raw signals of metal loss were revisited, which indicated this associated metal loss appears to be a crack rather than corrosion. In-field investigation revealed that this dent is indeed associated with branched cracks both at internal and external pipe surface but no leak was detected. The primary objective of this case study is to determine the cause for cracking in the dent. As part of this study, detailed investigation was performed including LaserScan based strain analysis, lab pressure-cycle testing and fracture surface examination. An attempt was made to quantify the plastic strain damage of this dent and its susceptibility to cracking using the existing plastic damage models, namely, ductile failure damage indicator (DFDI), strain limit damage (SLD) and minimum elongation limit criterion. The investigation showed that the internal cracks were formed at the time of indentation while the external cracks formed by spring-back (elastic rebounding) due to the removal of rock constraint. Full size fatigue testing of this cracked dent showed leak failure modes rather than rupture. In this paper, the approach, results and the findings are summarized and discussed.

Static bending strength assessment of sandwich panels with glass/polypropylene faces and aluminum foam cores

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040016
Author(s):  
Yi-Ming Jen ◽  
Zih-He Tang
Keyword(s):  
Aluminum Foam ◽  
Failure Modes ◽  
Shear Failure ◽  
Bending Strength ◽  
Sandwich Beam ◽  
Prediction Errors ◽  
Strength Assessment ◽  
Four Point Bending ◽  
Comparison Results ◽  
The Face

The four-point bending tests were performed first on the sandwich beam with glass/polypropylene faces and aluminum foam cores. The face thickness, core height, and angle-ply directions were considered as the variables to prepare the specimens. The effects of these variables on the bending strengths and the failure modes of the studied sandwich beams were experimentally analyzed using an MTS 810 material testing system and a four-point bending jig. Experimental results show that four failure modes, i.e. face-sheet failure, local indentation, and two types of core shear failure, were observed for the specimens with various experimental variables. The theoretical strengths for the four failure modes were proposed based on the mechanical strengths of the faces and cores. Among the four theoretical strengths, the lowest one is selected as the predicted strength and the corresponding mode is the predicted failure mode. The comparison results between the predicted and experimental strengths and failure modes were provided in the study. Assessment results show that the prediction errors are found to be below 30% for most specimens.

Concrete Strength and Deformation Property under Sea Water Erosion Environment

2012 ◽  
Vol 446-449 ◽  
pp. 2554-2559 ◽  
Author(s):  
Jian Jun Cai ◽  
Feng Zhang ◽  
Wei Cui ◽  
Shou Shan Chen ◽  
Pu Lun Liu
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Deformation Property ◽  
Sea Water ◽  
Dynamic Stiffness ◽  
Concrete Strength ◽  
Strain Curve ◽  
Water Erosion ◽  
Strength And Deformation ◽  
Erosion Environment

In order to effectively assess the concrete strength and deformation property under sea water erosion environment, concrete stress and strain curve was researched with the number of wet and dry cycle of 0 times, 10 times , 20 times, 30 times, 40 times, 50 times and 60 times based on the large-scale static and dynamic stiffness servo test set. The stress - strain curves of concrete was tested for the lateral pressure 10.8MPa, 14.4MPa, and 18.8MPa at different dry-wet cycles, The failure modes and superficial cracking characteristics of specimens are reported at different dry-wet cycles. Concrete elastic modulus and compressive strength were researched. Based on concrete mechanical theory , the classic Kufer-Gerstle strength criteria of concrete was used, a large number of test samples of multivariate data were nonlinear regressed, a biaxial concrete strength criterion was established taking into account the stress ratio and the number of dry-wet cycles.

A Strain Based Criterion to Evaluate the Tensile Capacity of Transmission Pipelines Under Large Scale Cyclic Bending

2018 ◽  
Author(s):  
Y. Andrés Plata Uribe ◽  
Claudio Ruggieri
Keyword(s):  
Structural Steel ◽  
Large Scale ◽  
Axial Loading ◽  
Tensile Failure ◽  
Void Coalescence ◽  
Ductile Crack ◽  
Tubular Specimen ◽  
Pipe Surface ◽  
Cracking Behavior ◽  
Tension Tests

This study explores the capability of a computational cell methodology and a stress-modified, critical strain (SMCS) criterion for void coalescence implemented into a large scale, 3-D finite element framework to model ductile fracture behavior in tensile specimens and in damaged pipelines. In particular, the cell methodology provides a convenient approach for ductile crack extension suitable for large scale numerical analyses which includes a damage criterion and a microstructural length scale over which damage occurs. A series of tension tests conducted on notched tensile specimens with different notch radius for a carbon steel pipe provides the stress-strain response of the tested structural steel from which the cell parameters and the SMCS criterion are calibrated. To investigate ductile cracking behavior in damaged pipelines, full scale cyclic bend tests were performed on a 165 mm O.D tubular specimen with 11 mm wall thickness made of a pipeline steel with very similar mechanical characteristics to the structural steel employed in the tension tests. The tubular specimen was initially subjected to indentation by 3-point bend loading followed by a compressive axial loading to generate large localized buckling in the dented region. The axial loading was then reversed to a tension loading applied until a visible ductile crack could be observed in the pipe surface. These exploratory analyses predict the tensile failure load for the pipe specimen associated with ductile crack initiation in the highly damaged area inside the denting and buckling zone which is in good agreement with experimental measurements.

scholarly journals Machine learning-based feature importance approach for sensitivity analysis of steel frames

2021 ◽  
Author(s):  
Hyeyoung Koh ◽  
Hannah Beth Blum
Keyword(s):  
Machine Learning ◽  
Sensitivity Analysis ◽  
Feature Selection ◽  
Large Scale ◽  
Failure Modes ◽  
Model Development ◽  
Predictive Performance ◽  
Computational Effort ◽  
Structural Systems ◽  
Feature Importance

This study presents a machine learning-based approach for sensitivity analysis to examine how parameters affect a given structural response while accounting for uncertainty. Reliability-based sensitivity analysis involves repeated evaluations of the performance function incorporating uncertainties to estimate the influence of a model parameter, which can lead to prohibitive computational costs. This challenge is exacerbated for large-scale engineering problems which often carry a large quantity of uncertain parameters. The proposed approach is based on feature selection algorithms that rank feature importance and remove redundant predictors during model development which improve model generality and training performance by focusing only on the significant features. The approach allows performing sensitivity analysis of structural systems by providing feature rankings with reduced computational effort. The proposed approach is demonstrated with two designs of a two-bay, two-story planar steel frame with different failure modes: inelastic instability of a single member and progressive yielding. The feature variables in the data are uncertainties including material yield strength, Young’s modulus, frame sway imperfection, and residual stress. The Monte Carlo sampling method is utilized to generate random realizations of the frames from published distributions of the feature parameters, and the response variable is the frame ultimate strength obtained from finite element analyses. Decision trees are trained to identify important features. Feature rankings are derived by four feature selection techniques including impurity-based, permutation, SHAP, and Spearman's correlation. Predictive performance of the model including the important features are discussed using the evaluation metric for imbalanced datasets, Matthews correlation coefficient. Finally, the results are compared with those from reliability-based sensitivity analysis on the same example frames to show the validity of the feature selection approach. As the proposed machine learning-based approach produces the same results as the reliability-based sensitivity analysis with improved computational efficiency and accuracy, it could be extended to other structural systems.

scholarly journals Large-scale application of the flood damage model RAilway Infrastructure Loss (RAIL)

2016 ◽  
Vol 16 (11) ◽  
pp. 2357-2371 ◽  
Author(s):  
Patric Kellermann ◽  
Christine Schönberger ◽  
Annegret H. Thieken
Keyword(s):  
Risk Management ◽  
Risk Aversion ◽  
Flood Risk ◽  
Structural Damage ◽  
Large Scale ◽  
Damage Model ◽  
Flood Damage ◽  
Railway Infrastructure ◽  
Increased Risk ◽  
The Impact

Abstract. Experience has shown that river floods can significantly hamper the reliability of railway networks and cause extensive structural damage and disruption. As a result, the national railway operator in Austria had to cope with financial losses of more than EUR 100 million due to flooding in recent years. Comprehensive information on potential flood risk hot spots as well as on expected flood damage in Austria is therefore needed for strategic flood risk management. In view of this, the flood damage model RAIL (RAilway Infrastructure Loss) was applied to estimate (1) the expected structural flood damage and (2) the resulting repair costs of railway infrastructure due to a 30-, 100- and 300-year flood in the Austrian Mur River catchment. The results were then used to calculate the expected annual damage of the railway subnetwork and subsequently analysed in terms of their sensitivity to key model assumptions. Additionally, the impact of risk aversion on the estimates was investigated, and the overall results were briefly discussed against the background of climate change and possibly resulting changes in flood risk. The findings indicate that the RAIL model is capable of supporting decision-making in risk management by providing comprehensive risk information on the catchment level. It is furthermore demonstrated that an increased risk aversion of the railway operator has a marked influence on flood damage estimates for the study area and, hence, should be considered with regard to the development of risk management strategies.

scholarly journals PENNSYLVANIA’S ABANDONED MINE LAND (AML) EMERGENCY PROGRAM

2020 ◽  
Vol 9 (4) ◽  
pp. 67-86
Author(s):  
Eric E. Cavazza ◽  
◽  
John J. Stefanko ◽  
Richard L. Beam
Keyword(s):  
Structural Damage ◽  
Large Scale ◽  
Mine Drainage ◽  
Abandoned Mine ◽  
Annual Number ◽  
House Construction ◽  
Mine Fires ◽  
Coal Refuse ◽  
Eastern Pennsylvania ◽  
Engineering Staff

Abstract. The Pennsylvania Department of Environmental Protection’s Bureau of Abandoned Mine Reclamation (BAMR) implements an Abandoned Mine Land (AML) Emergency Program to address high-priority, abandoned mine land (AML) problems that suddenly occur throughout Pennsylvania’s coal fields. BAMR maintains two field offices: one in eastern Pennsylvania (Anthracite Region) in Wilkes-Barre and one in western Pennsylvania (Bituminous Region) in Ebensburg. Both field offices maintain in-house construction crews with significant equipment available to respond to and address many small AML Emergencies (hazards) such as pothole (or cavehole), subsidences, and mine drainage breakouts. For larger AML Emergencies such as subsidence events causing structural damage to homes, businesses, and roads; mine fires; coal refuse fires; landslides; or other large-scale or complex AML problems, projects are completed by outside contractors. Project designs are completed by BAMR engineering staff. The contractors are then hired through solicitation of bids or proposals with very short timeframes between bid issue and bid opening. Since October of 2010, BAMR has addressed nearly 800 AML Emergencies which equates to approximately 80 AML Emergency projects each calendar year. The average construction cost to address those emergencies was just over $3.25 million per year. Due to the increased precipitation over the Commonwealth the last several years, that number has increased to an average of 86 AML Emergency projects over the last five (5) years (2015–2019) with a record number of 127 addressed in calendar year 2018. The average cost to address those AML Emergency projects over that five-year period was $4.66 million per year. This paper will provide some background on Pennsylvania’s AML Emergency Program, some summary statistics including the annual number and types of projects completed including costs, and also highlight through both photos and video links some typical projects recently completed by the program.

scholarly journals Enhancing Strength of Bamboo using GFRP and PU

2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Teoh Hui Xin ◽  
◽  
Norazman Mohamad Nor ◽  
Mohammed Alias Yusof ◽  
◽  
...  
Keyword(s):  
Glass Fiber ◽  
Bending Strength ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Glass Fiber Reinforced Polymer ◽  
Bearing Strength ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Bending Capacity ◽  
Work Done

Bamboo is an eco-friendly material, it can be used in various applications such as bamboo housing, bamboo bridges, bamboo scaffolding, ply bamboo, bamboo furniture, and for defence applications. It has various advantages to be used as structural material. However, it has weaknesses such as crushing failure under extreme loading that need to be addressed. The objective of this research is to enhance bamboo bearing and bending capacity using various stiffeners. Experimental work done is to investigate the compressive strength, bending strength, bearing strength and tensile strength of raw local bamboo. Further analysis includes bending and bearing strength of raw bamboo and strengthen bamboo using Glass Fiber Reinforced Polymer (GFRP) and Polyurethane (PU) Foams. From the test done, the bearing strength of raw bamboo Semantan with node is between 2.61 MPa to 3.14 MPa and for raw bamboo Semantan without node is between 0.28 MPa to 0.82 MPa, average bending strength of raw bamboo Semantan is 59 MPa. For strengthen bamboo with 4 layers of Glass Fiber Reinforced Polymer, the bearing strength without node is between 1.59 MPa to 2.38 MPa, and the average bending strength is 62 MPa which is about 5% higher than raw bamboo.

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