scholarly journals Seismic Behaviour of Buried Pipelines: 3D Finite Element Approach

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Smrutirekha Sahoo ◽  
Bappaditya Manna ◽  
K. G. Sharma
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Ground Deformation ◽  
Seismic Wave Propagation ◽  
Pipe Diameter ◽  
Bend Angle ◽  
Burial Depth ◽  
Maximum Magnitude ◽  
Buried Pipelines ◽  
Seismic Behaviour

This paper presents a numerical investigation on six pipeline models to study the seismic response of single and double buried pipelines using finite element method. Different depth and spacing of pipes are considered to investigate their prominent role in the seismic response of buried pipelines under an earthquake loading having PGA of 0.2468 g. In case of single pipeline, the maximum magnitude of final displacement as well as the stress at the end of the seismic sequence is found at the burial depth equal to the pipe diameter. In case of double pipeline, the maximum magnitude of final displacement is found when the spacing between pipes is equal to half the pipe diameter and there is an increasing tendency of developed stress with increase in spacing between pipes. In addition to the above results, the response of the buried pipelines with a particular bend angle (artificially induced bend/buckle) to the permanent ground deformation which is assumed to be the result of seismic wave propagation has also been studied. Remarkable differences in these results are obtained and with these results the designers can reduce seismic risk to their buried pipelines by taking proper precautionary measures.

scholarly journals Seismic behaviour of a large-scale concrete-block retaining wall

2019 ◽  
Vol 92 ◽  
pp. 16007
Author(s):  
Noboru Sato ◽  
Toshikazu Sawamatsu ◽  
Takehiko Nitta ◽  
Hiroaki Miyatake ◽  
Kazuhito Kondo
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Large Scale ◽  
Retaining Wall ◽  
Fem Simulation ◽  
Concrete Block ◽  
Scale Model ◽  
Seismic Behaviour ◽  
Experimental Conditions ◽  
Concrete Blocks

In this study, an inclined model experiment and finite element analyses were conducted to evaluate the failure mode and seismic response of a dry-type large-scale concrete-block retaining wall (LCBW). In the experiment, the objective was to reproduce the sliding between concrete blocks that was observed in past cases LCBW damage in order to characterise the behaviour until failure. A numerical simulation corresponding to the experimental conditions was conducted by the finite element method (FEM). Dynamic analyses were also performed by FEM to investigate the seismic response of the concrete blocks under various ground conditions. The experimental results revealed that slip between the concrete blocks caused brittle failure of the LCBW. In the FEM simulation, the joint elements reproduced the experimentally observed sliding between the concrete blocks. A dynamic simulation of the full-scale model revealed that significant sliding and rocking of the concrete block occur in a dry-type LCBW. These findings indicate that stress concentration may occur at the heels of the concrete blocks during an earthquake.

Numerical Investigation of Thermal Fields Around Subsea Buried Pipelines

2014 ◽  
Author(s):  
Yanbin Bai ◽  
John M. Niedzwecki ◽  
Marcelo Sanchez
Keyword(s):  
Finite Element ◽  
Temperature Distribution ◽  
Boundary Element ◽  
The Arctic ◽  
Large Temperature ◽  
Soil Conditions ◽  
Burial Depth ◽  
Buried Pipelines ◽  
Long Distance ◽  
Technical Problems

Subsea pipelines transporting hydrocarbons from very deepwater wells or at arctic sites for long distances present some challenging technical problems. The ambient temperature at the seafloor in deepwater may be about 5°C (∼ 41°F or 278 K) and can be even lower in the arctic regions, while the wellhead hydrocarbon temperatures can be in excess of 149°C (∼ 300°F or 422 K). Insulation of these buried pipelines to mitigate this large temperature gradient can be only part of the solution as temperature losses over long distance may require heating systems to avoid deposition of impurities and clogging of the pipeline. The near field thermal gradient in surrounding soil is investigated using complementary 2-D numerical simulations of finite element and boundary element numerical models. A finite element hydraulic-thermal code designed for porous media was used to investigate the time evolution of the natural convection effects due to pipeline heating of the seawater in soil. For a seabed of clay under these conditions, it was determined that the boundary element model could be directed at steady state heat transfer about the pipeline in layered soil conditions addressing trenching and backfill consistent with the burial of the pipeline by a remotely operated vehicle. Parameters that may affect the thermal field around the subsea buried pipeline such as burial depth, thermal power loss and thermal properties of backfilling soils were investigated. It was shown that the thermal conductivity of the backfill has a critical influence on temperature distribution at the pipe wall, and that the pipe burial depth significantly affects temperature distribution on the seabed right above the pipe in deepwater.

Analytical Model for Segmented Pipe Response to Tensile Ground Strain

2016 ◽  
Vol 32 (4) ◽  
pp. 2533-2548 ◽  
Author(s):  
Michael O'Rourke ◽  
Tatiana Vargas-Londono
Keyword(s):  
Cast Iron ◽  
Ground Deformation ◽  
Large Diameter ◽  
Small Diameter ◽  
Seismic Wave Propagation ◽  
Seismic Fragility ◽  
Buried Pipelines ◽  
Empirical Relations ◽  
Permanent Ground Deformation ◽  
Pipe Materials

Seismic fragility relations for segmented buried pipelines have, up to this point, been based almost exclusively upon empirical observations. There are drawbacks with the purely empirical approach, one being the lack of confidence in estimated damage for the more important large diameter pipelines. This paper presents mechanics-based models for small diameter cast iron pipelines subject to tensile ground strains. One model is for small to moderate ground strains (less than .0002) primarily associated with seismic wave propagation. A second model is for larger ground strains associated with the permanent ground deformation hazard. The predicted damage rates from these mechanics-based models are consistent with existing empirical relations for small diameter cast iron pipe. It is expected that in the future, these mechanics-based models can be extended to the more important large diameters and to different pipe materials.

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

Seismic Response Analysis of Soil-Structure Interaction on Base Isolation Structure

2013 ◽  
Vol 663 ◽  
pp. 87-91
Author(s):  
Ying Bo Pang
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Base Isolation ◽  
Soil Structure Interaction ◽  
Response Analysis ◽  
Analysis Model ◽  
Seismic Response Analysis ◽  
Structure Interaction ◽  
Calculation Results

As an effective way of passive damping, isolation technology has been widely used in all types of building structures. Currently, for its theoretical analysis, it usually follows the rigid foundation assumption and ignores soil-structure interaction, which results in calculation results distortion in conducting seismic response analysis. In this paper, three-dimensional finite element method is used to establish finite element analysis model of large chassis single-tower base isolation structure which considers and do not consider soil-structure interaction. The calculation results show that: after considering soil-structure interaction, the dynamic characteristics of the isolation structure, and seismic response are subject to varying degrees of impact.

Effect of Pile-Soil-Structure Interaction on the Cable-Stayed Bridge in Response to the Earthquake

2014 ◽  
Vol 539 ◽  
pp. 731-735 ◽  
Author(s):  
Yu Chen
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Soil Structure ◽  
Response Spectrum ◽  
Three Dimensional ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Cable Stayed Bridge ◽  
Three Dimensional Finite Element

In this thesis, based on the design of a 140+90m span unusual single tower and single cable plane cable-stayed bridge, free vibration characteristics and seismic response are investigated; three dimensional finite element models of a single tower cable-stayed bridge with and without the pile-soil-structure interaction are established respectively by utilizing finite element software MIDAS/CIVIL, seismic response of Response spectrum and Earthquake schedule are analyzed respectively and compared. By the comparison of the data analysis, for small stiffness span cable-stayed bridge, the pile-soil-structure interaction can not be ignored with calculation and analysis of seismic response.

Comparison of Buried Pipeline Crossing Assessments Using API RP 1102, Analytical Method and Finite Element Approach

2020 ◽  
Author(s):  
Nikhil Joshi ◽  
Pritha Ghosh ◽  
Jonathan Brewer ◽  
Lawrence Matta
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Rapid Assessment ◽  
Buried Pipeline ◽  
The Finite Element Method ◽  
Buried Pipelines ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Element Approach ◽  
Multiple Loading

Abstract API RP 1102 provides a method to calculate stresses in buried pipelines due to surface loads resulting from the encroachment of roads and railroads. The API RP 1102 approach is commonly used in the industry, and widely available software allows for quick and easy implementation. However, the approach has several limitations on when it can be used, one of which is that it is limited to pipelines crossing as near to 90° (perpendicular crossing) as practicable. In no case can the crossing be less than 30° . In this paper, the stresses in the buried pipeline under standard highway vehicular loading calculated using the API RP 1102 method are compared with the results of two other methods; an analytical method that accounts for longitudinal and circumferential through wall bending effects, and the finite element method. The benefit of the alternate analytical method is that it is not subject to the limitations of API RP 1102 on crossing alignment or depth. However, this method is still subject to the limitation that the pipeline is straight and at a uniform depth. The fact that it is analytical in nature allows for rapid assessment of a number of pipes and load configurations. The finite element analysis using a 3D soil box approach offers the greatest flexibility in that pipes with bends or appurtenances can be assessed. However, this approach is time consuming and difficult to apply to multiple loading scenarios. Pipeline crossings between 0° (parallel) and 90° (perpendicular) are evaluated in the assessment reported here, even though these are beyond the scope of API RP 1102. A comparison across the three methods will provide a means to evaluate the level of conservatism, if any, in the API RP 1102 calculation for crossing between 30° and 90° . It also provides a rationale to evaluate whether the API RP 1102 calculation can potentially be extended for 0° (parallel) crossings.

scholarly journals Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Chen Xia ◽  
Chengzhi Qi ◽  
Xiaozhao Li
Keyword(s):  
Finite Element ◽  
Seismic Response ◽  
Time Domain ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Seismic Loads ◽  
Element Analysis ◽  
Artificial Boundaries ◽  
The Time Domain ◽  
Transmitting Boundaries

Transmitting boundaries are important for modeling the wave propagation in the finite element analysis of dynamic foundation problems. In this study, viscoelastic boundaries for multiple seismic waves or excitations sources were derived for two-dimensional and three-dimensional conditions in the time domain, which were proved to be solid by finite element models. Then, the method for equivalent forces’ input of seismic waves was also described when the proposed artificial boundaries were applied. Comparisons between numerical calculations and analytical results validate this seismic excitation input method. The seismic response of subway station under different seismic loads input methods indicates that asymmetric input seismic loads would cause different deformations from the symmetric input seismic loads, and whether it would increase or decrease the seismic response depends on the parameters of the specific structure and surrounding soil.

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