Performance Assessment of Buried Pipelines at Fault Crossings

2017 ◽  
Vol 33 (1) ◽  
pp. 201-218 ◽  
Author(s):  
Vasileios E. Melissianos ◽  
Dimitrios Vamvatsikos ◽  
Charis J. Gantes
Keyword(s):  
Performance Assessment ◽  
Hazard Analysis ◽  
Limit State ◽  
Three Dimensional ◽  
Structural Response ◽  
Element Model ◽  
Seismic Performance Assessment ◽  
Capacity Uncertainty ◽  
Beam Type ◽  
Fault Displacement

A methodology for seismic performance assessment of onshore buried steel pipelines at fault crossings is presented. Probabilistic fault displacement hazard analysis is performed at first to determine the magnitude of the three fault displacement components in space. Next, three-dimensional (3-D) structural analysis of the pipeline via a nonlinear beam-type finite element model allows accounting for the different effect of imposed displacements in each axis. Finally, convolving of seismic hazard and structural response results in joint hazard surfaces of compressive and tensile strains that can be used to estimate the mean annual rate of exceeding any limit-state of interest under the influence of demand and capacity uncertainty.

Reliability-Based Assessment Method of Buried Pipeline at Fault Crossings

2020 ◽  
Author(s):  
Qian Zheng ◽  
Xiaoben Liu ◽  
Hong Zhang ◽  
Samer Adeeb
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Finite Element Model ◽  
Limit State ◽  
Element Model ◽  
Normal Operation ◽  
Operating Pressure ◽  
Peak Strain ◽  
Highly Nonlinear ◽  
Fault Displacement

Abstract The tectonic fault, which is one of the most common geohazards in field, poses great threat to buried pipe segments. Pipes will process to buckling or fracture due to large strain induced by continuously increasing ground displacements during earthquakes. Therefore, it is imperative to conduct safety analysis on pipes which are buried in seismic areas for the sake of ensuring normal operation. However, the highly nonlinearity of pipe response restricts the proceeding of reliability assessment. In this study, a hybrid procedure combining finite element method and artificial neural network is proposed for reliability-based assessment. First of all, the finite element model is developed on ABAQUS platform to simulate pipe response to strike-slip fault displacements. Thus, the strain demand value (the peak strain value obtained by finite element model in each design case) can be collected for database establishment, which is the preparation for neural network training. Thoroughness of the strain demand database can be achieved by a fully comprehensive calculation with consideration of influencing factors involving pipe diameter and wall thickness, operating pressure, magnitude of fault displacement, intersection angle between pipeline and fault plane, and characteristic value of backfill mechanics. Sequentially, Back Propagation Neural Network (BPNN) with double hidden layers is trained based on the developed database, and the surrogate strain demand prediction model can be obtained after accuracy verification. Hence, the strain-based limit state function can be respectively determined for tensile and compressive conditions. The strain capacity term is simply assumed based on published papers, the strain demand term is naturally superseded by the surrogate BPNN model, and Monte Carlo Simulation is employed to compute the probability of failure (POF). At last, the workability of the proposed approach is tested by a case study in which basic variables are referred to the Second West-to-East natural gas transmission pipeline project. It indicates that ANN is a good solver for reliability problems with implicit limit state functions especially for highly nonlinear problems. The proposed method is capable of computing POFs, which is an exploratory application for reliability research on pipes withstanding fault displacement loads.

On the Structural Response of a Flexible Pipe With Damaged Tensile Armor Wires

2011 ◽  
Author(s):  
Jose´ Renato M. de Sousa ◽  
George C. Campello ◽  
Antoˆnio Fernando B. Bueno ◽  
Eduardo Vardaro ◽  
Gilberto B. Ellwanger ◽  
...  
Keyword(s):  
Mechanical Response ◽  
High Stress ◽  
Three Dimensional ◽  
Structural Response ◽  
Experimental Tests ◽  
Element Model ◽  
Axial Stiffness ◽  
Stress Concentrations ◽  
Flexible Pipe ◽  
Flexible Pipes

This paper studies the structural response of a 6.0″ flexible pipe under pure tension considering two different situations: the pipe is intact or has five wires broken in its outer tensile armor. A three-dimensional nonlinear finite element model devoted to analyze the local mechanical response of flexible pipes is employed in this study. This model is capable of representing each wire of the tensile armors and, therefore, localized defects, including total rupture, may be adequately represented. Results from experimental tests are also presented in order to validate the theoretical estimations. The theoretical and experimental results indicate that the imposed damage reduced the axial stiffness of the pipe. High stress concentrations in the wires near the damaged ones were also observed and, furthermore, the stresses in the inner carcass and the pressure armor are affected by the imposed damage, but, on the other hand, the normal stresses in the wires of the inner tensile armor are not.

scholarly journals Probabilistic Assessment of Innovative Mitigating Measures for Buried Steel Pipeline–Fault Crossing

2015 ◽  
Author(s):  
Vasileios E. Melissianos ◽  
Dimitrios Vamvatsikos ◽  
Charis J. Gantes
Keyword(s):  
Hazard Analysis ◽  
Structural Response ◽  
Comprehensive Analysis ◽  
Effectiveness Evaluation ◽  
Second Step ◽  
Flexible Joints ◽  
Intensity Measure ◽  
Seismological Data ◽  
Fault Displacement ◽  
Probabilistic Nature

A methodology is presented on assessing the effectiveness of flexible joints in mitigating the consequences of faulting on buried steel pipelines through a comprehensive analysis that incorporates the uncertainty of fault displacement magnitude and the response of the pipeline itself. The proposed methodology is a two-step process. In the first step the probabilistic nature of the fault displacement magnitude is evaluated by applying the Probabilistic Fault Displacement Hazard Analysis, considering also all pertinent uncertainties. The second step is the “transition” from seismological data to the pipeline structural response through the fault displacement components as the adopted vector intensity measure. To mitigate the consequences of faulting on pipelines, flexible joints between pipeline parts are proposed as innovative measure for reducing the deformation of pipeline walls. Thus, the mechanical behavior of continuous pipelines and pipelines with flexible joints is numerically assessed and strains are extracted in order to develop the corresponding strain hazard curves. The latter are a useful engineering tool for pipeline – fault crossing risk assessment and for the effectiveness evaluation of flexible joints as innovative mitigating measures against the consequences of faulting on pipelines.

Behaviour and design of composite beams with composite slabs at elevated temperatures

2016 ◽  
Vol 20 (10) ◽  
pp. 1451-1465 ◽  
Author(s):  
Shou-Chao Jiang ◽  
Gianluca Ranzi ◽  
Ling-Zhu Chen ◽  
Guo-Qiang Li
Keyword(s):  
Elevated Temperatures ◽  
Numerical Study ◽  
Three Dimensional ◽  
Structural Response ◽  
Load Ratio ◽  
Element Model ◽  
Composite Beams ◽  
European Guidelines ◽  
Design Fire ◽  
Composite Slabs

This article presents an extensive experimental and numerical study aimed at the evaluation of the thermo-structural response of composite beams with composite slabs. Two full-scale fire tests were carried out on simply supported composite steel-concrete beams with steel sheeting perpendicular and parallel to the steel joist, respectively. Both specimens were observed to fail by developing large displacements. Concrete crushing at the mid-span, debonding of the profiled sheeting and spalling of the fire protection were observed during both tests. A three-dimensional finite element model was developed in ABAQUS, and its accuracy was validated against the experimental measurements collected as part of this study. The model was then used to perform a parametric study to determine the influence of the degree of shear connection, load ratio and design fire rate on the structural response of composite beams at elevated temperatures. These results, together with experimental data available in the literature, were used to evaluate the ability of European guidelines to predict the critical temperature of composite beams. It was shown that predictions from Eurocode 4 were safe and provided conservative estimates for most cases.

scholarly journals Drop Simulation of 6M Drum With Locking-Ring Closure and Liquid Contents

2006 ◽  
Author(s):  
Tsu-Te Wu
Keyword(s):  
Impact Load ◽  
Three Dimensional ◽  
Structural Response ◽  
Material Model ◽  
Element Model ◽  
Ring Closure ◽  
Foot Drop ◽  
Torque Load ◽  
Three Dimensional Finite Element ◽  
The Impact

This paper presents the dynamic simulation of the 6M drum with a locking-ring type closure subjected to a 4.9-foot drop. The drum is filled with water to 98 percent of overflow capacity. A three dimensional finite-element model consisting of metallic, liquid and rubber gasket components is used in the simulation. The water is represented by a hydrodynamic material model in which the material’s volume strength is determined by an equation of state. The explicit numerical method based on the theory of wave propagation is used to determine the combined structural response to the torque load for tightening the locking-ring closure and to the impact load due to the drop.

Vector and Scalar IMs in Structural Response Estimation, Part II: Building Demand Assessment

2016 ◽  
Vol 32 (3) ◽  
pp. 1525-1543 ◽  
Author(s):  
Mohsen Kohrangi ◽  
Paolo Bazzurro ◽  
Dimitrios Vamvatsikos
Keyword(s):  
Ground Motion ◽  
Hazard Analysis ◽  
Three Dimensional ◽  
Structural Response ◽  
Response Assessment ◽  
Companion Paper ◽  
Period Range ◽  
Intensity Measures ◽  
Advantages And Disadvantages ◽  
Story Drift

The advantages and disadvantages of using scalar and vector ground motion intensity measures (IMs) are discussed for the local, story-level seismic response assessment of three-dimensional (3-D) buildings. Candidate IMs are spectral accelerations, at a single period ( Sa) or averaged over a period range ( Sa avg). Consistent scalar and vector probabilistic seismic hazard analysis results were derived for each IM, as described in the companion paper in this issue ( Kohrangi et al. 2016 ). The response hazard curves were computed for three buildings with reinforced concrete infilled frames using the different IMs as predictors. Among the scalar IMs, Sa avg tends to be the best predictor of both floor accelerations and inter story drift ratios at practically any floor. However, there is an improvement in response estimation efficiency when employing vector IMs, specifically for 3-D buildings subjected to both horizontal components of ground motion. This improvement is shown to be most significant for a tall plan-asymmetric building.

scholarly journals Human comfort assessment of buildings subjected to nondeterministic wind dynamic loadings

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Alan Barile ◽  
Leonardo de Souza Bastos ◽  
José Guilherme Santos da Silva
Keyword(s):  
Coherence Function ◽  
Research Work ◽  
Three Dimensional ◽  
Structural Response ◽  
Element Model ◽  
Spectral Density Function ◽  
Human Comfort ◽  
Analysis Methodology ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

ABSTRACT A reliable human comfort assessment depends on the correct description of the wind dynamic loads when compared with studies of natural wind. Thus, in this research work an analysis methodology was developed aiming to generate nondeterministic dynamic wind loadings, based on a power spectral density function and coherence function. This way, aiming to test the developed analysis methodology, a forced vibration dynamic analysis was carried out, based on a three-dimensional finite element model developed to represent a real and existing thirty-storey reinforced concrete building, with total height of 90 m, store height equal to 3 m and rectangular dimensions of 21.50 m by 17.30 m. The dynamic structural response of the investigated building was evaluated, the accelerations at the top of the structure were calculated and the human comfort was verified. The results obtained along this research work indicate that the peak accelerations calculated for periods of recurrence equal to 10 years and 1 year, respectively, overpass the recommended limits proposed by the NBR 6123 and ISO 10137.

Risk-Based Seismic Performance Assessment of Pressurized Piping Systems Considering Ratcheting

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
A. Ravi Kiran ◽  
G. R. Reddy ◽  
M. K. Agrawal
Keyword(s):  
Performance Assessment ◽  
Seismic Performance ◽  
Fragility Curves ◽  
Limit State ◽  
Frequency Variation ◽  
Seismic Load ◽  
Piping System ◽  
Seismic Performance Assessment ◽  
Limit States ◽  
Piping Systems

Abstract A procedure is described for risk-based seismic performance assessment of pressurized piping systems considering ratcheting. The procedure is demonstrated on a carbon steel piping system considered for OECD-NEA benchmark exercise on quantification of seismic margins. Initially, fragility analysis of the piping system is carried out by considering variability in damping and frequency. Variation in damping is obtained from the statistical analysis of the damping values observed in earlier experiments on piping systems and components. The variation in ground motion is considered by using 20 strong motion records of the intraplate region. Floor motion of a typical reactor building of a nuclear power plant under these actual earthquake records is evaluated and applied to the piping system. The performance evaluation of the piping system in terms of ratcheting is carried out using a numerical approach, which was earlier validated with shake table ratcheting tests on piping components and systems. Three limit states representing performance levels of the piping system under seismic load are considered for fragility evaluation. For each limit state, probability of exceedance at different levels of floor motion is evaluated to generate a fragility curve. Subsequently, the fragility curves of the piping systems are convoluted with hazardous curves for a typical site to obtain the risk in terms of annual probability of occurrence of the performance limits.

Parametric finite element model for spiral welded pipes sections loaded in tension

2013 ◽  
Vol 4 (1) ◽  
Author(s):  
Koen Van Minnebruggen ◽  
Philippe Thibaux ◽  
Jeroen Van Wittenberghe ◽  
Rudi Denys ◽  
Wim De Waele
Keyword(s):  
Finite Element ◽  
Heat Affected Zone ◽  
Material Properties ◽  
Oil And Gas ◽  
Yield Criterion ◽  
Three Dimensional ◽  
Structural Response ◽  
Element Model ◽  
Pipe Geometry ◽  
Actual Geometry

  Spiral welded pipes gain interest for oil and gas transportation in strain based design projects. Here, the structural response of the pipe with an environmentally imposed global plastic strain is of critical importance. However, a current lack of knowledge about the structural response of a spiral welded pipeline hinders the application in a strain based design context. This response is not only influenced by material properties, but also by geometrical characteristics. To understand these complex phenomena, finite element simulations can be considered. The finite element models need to incorporate all important factors to obtain a representative analysis. This paper describes the approach and structure used to develop such model. To obtain a high degree of automation and flexibility, the authors have developed a parametric script that allows creating a three dimensional curved wide plate test geometry taken from a spiral welded pipe. The model allows to modify pipe geometry, weld and heat affected zone geometry and material properties including Hill’s 1948 yield criterion to account for anisotropic material response. Pipe geometry includes helical forming angle, diameter, pipe profile and wall thickness with possible thickness variations. Weld and heat affected zone geometry include geometrical weld reinforcement of root and/or cap, fusion line profile and misalignment. A flaw, with variable size, is introduced in the weld metal or heat affected zone. To obtain an accurate description of the actual geometry, coordinate transformation schemes are incorporated that start from a flat plate with a simplified girth weld geometry. It is concluded that the proposed model is ready for use with a good view on mesh quality and output accuracy.

Sign in / Sign up

Export Citation Format

Share Document