EX C H A N G E Risk

EXperimental & Computational Hybrid Assessment of Natural

Gas Pipelines Exposed to Seismic Risk

Project Meeting

Friday September 1st, 2017

Project Meeting agenda Wednesday 12th April, University of Toronto, Canada (Local Time) – Teleconference with remote partners

ChallengeImportance Objectives WorkshopProject

WP01 State-of-the-art on the performance of seismically excited NG pipelines

• Investigate the literature and interact with the partners of the project from the Oil & Gas industry to form a comprehensive state-of-the-art on natural gas pipeline systems and networks as well as their performance under seismic loading.

• Populate the state-of-the-art with existing measurements from onsite pipeline monitoring and on site inspection methods obtained through the participating SMEs.


Hybrid experimentation on principle failure modes of the soil-pipeline system

WP02


3D numerical simulation of soil-pipeline interaction

WP03

• 2D/3D Finite Element models for soil-pipeline interaction• Develop the numerical modules required for the main

Hybrid Test prescribed in WP02 and new macro-elements for soil-pipeline interaction after experimental validation (WP02)


Analytical & numerical prediction of spatially variable permanent ground displacements of long NG pipelines

WP04

• A comprehensive analytical and numerical methodology to reliably predict the spatial and temporal variation of seismically induced strains and deformations along a pipeline segment, considering spatial variability of earthquake ground motion and soil-structure interaction.

• Extrapolation from Bridges to Natural Gas Pipelines


Multi-damage seismic risk assessment of soil-NG pipeline networks

WP05

• Fragility relationships for pipelines considering the experimentally defined limit stage for multiple damage modes (WP02), soil-pipe interface compliance (WP03), spatial variation of earthquake ground motion along the pipeline (WP04) and different angles of seismic wave incidence (WP04).

• Multi-damage fragility of a single pipeline segment (from connection to connection)

• Seismic Risk of NG pipelines at a Network level based on the performance indicators identified in WP01 simultaneously considering multiple failure modes of the pipes.


NG Pipeline inspection and health monitoring for maintenance and rehabilitation

WP06

• Cost-effective monitoring technologies to detect and localize damage for assessing the safety of accessible and non-accessible NG pipelines rapidly after a major earthquake event at specific locations of the Network identified probabilistically (WP07).


Rapid stochastic assessment of post-earthquake health of NG pipelines

WP07

• Develop the DEcision Support System for RApid Pipeline Recovery (DESSRAP), i.e., a comprehensive methodology, softwareand operational recommendations for rapid stochastic assessment of post-earthquake health condition of buried steel pipelines in areas of potentially significant ground-induced deformations.

• Integrate the DESSRAP methodology in a Shake Map –based GIS Software development for Seismic Resilience of NG Networks

Financial Issues

Financial issues

• 65% pre-financing already paid = 545,400€ (909,000€*0,65-45,450 € guarantee fund)

• 50% of the CA to to EU academic partners (through them)

Financial issues

Compensation to industrial partners

Naples -> VCE completed

Naples -> NGI (in progress, from Naples)

Kiel -> VCE (through UoB)

Weimar -> VCE (through UoB)

UoB -> Hochtief (UoB)

AUTh -> NGI (through UoB)

Secondments for 2017, templates and rules

Prescribed secondments

Visits for 2016-19, templates and rules

• Minimum visit: 1 calendar month (not necessarily one-off, may be broken down in smaller visits provided that the person, host and sending institution remain the same)

• Maximum visit: 12 months • For 1<visits<12months: payment is computed based on a 30day month definition

Visits for 2016-19, templates and rules

• This can be slightly revisited (already modified slightly) as long as it does not change the budget and the scope and is approved by the PO.

Visits for 2016-early 2017

Secondments so far (accomplished only) = 25.7% Secondments so far (accomplished + initiated) = 37.6 % (75/202)Month 20/48 = 41.6%

Advisory Committee / Visit to Canada

• Spyros Karamanos, Professor & Chair, University of Edinburgh, UK & University of Thessaly, Greece

• Solomon Tesfamariam, Assoc. Professor, University of British Columbia, Canada

• Ad Shadat, Vice President, VP Operations of PICA, RussellTech, Canada

• Qishi Chen, Director, Pipelines & Structures, C-FER Technologies, Canada

Meeting with PO

• Anytime/Anywhere: end of October – early November

• Re-distribute man-months and funding (new Consortium Agreement may need to be re-signed)

• University of Massachusetts, Amherst as additional partner in the US

16ECEE, Thessaloniki, 2018 (next meeting / Special Session)

INFRASTRUCTURE RESILIENCE OF NATURAL GAS PIPELINE NETWORKS

International Workshop and Project Meeting Hochtief Engineering GmbH, Lyoner Strasse 25

D-60528 Frankfurt am Main, Germany Thursday 31 August –Friday 1 September 2017

PROGRAMME OUTLINE

Horizon 2020Call: H2020-MSCA-RISE-2015 Topic: MSCA-RISE-2015

Action: MSCA-RISE Proposal Number: 691213

Proposal Acronym: EXCHANGE-Risk Time Frame: 1-1-2016 to 31-12-2019, 48 months

Person Months: 202 Budget: € 950,000 Work Packages: 9

WP0: Management

WP1: State-of-the-art on the performance of seismically excited NG pipelines WP2: Hybrid experimentation on principle failure modes of soil-pipeline system WP3:3D numerical simulation of soil-pipeline-interaction WP4: Analytical and numerical prediction of spatially variable permanent ground displacements of long NG pipelines WP5:Multi-damage, multi-angle vulnerability of soil-NG pipeline networks WP6: NG pipeline inspection and health monitoring for maintenance and rehab WP7: Rapid stochastic assessment of post-earthquake health of NG pipelines WP8: Dissemination

PARTNER AUTH ARISTOTLE UNIVERSITY OF THESSALONIKI (AUTH)

SCHOOL OF ENGINEERING DEPARTMENT OF CIVIL ENGINEERING

DIVISION OF STRUCTURAL ENGINEERING

I. LABORATORY OF STRENGTH OF MATERIALS AND STRUCTURES & EARTHQUAKE SIMULATOR FACILITY II. LABORATORY OF APPLIED STATICS & DYNAMICS OF STRUCTURES Principal Investigator for AUTH: Professor George D. Manolis, Director Email: [email protected] Site Information: http://strength.civil.auth.gr, http://static.civil.auth.gr, http://statdyn.civil.auth.gr http://hcouper.weebly.com

mailto:[email protected]

http://strength.civil.auth.gr/

http://strength.civil.auth.gr/

http://statdyn.civil.auth.gr/

PAST AUTH PROJECT ON PIPELINES

Title: Seismic Behaviour and Vulnerability of Buried Lifelines Funded by: EC EPOCH Programme

Budget: Ecu 300,000 Time Period: 9/1991 to 12/1993

Researchers: Dr. Oswald Klingmuller, Coordinator for a Consortium of five Organizations including the AUTH group of D.G Talaslidis, G.D. Manolis & K. Pitilakis Sample Publications: O. Klingmuller, K. Makropoulos, D. Diamantidis, G.M. Manfredini, F. Zuccarelli, D. Talaslidis, K. Pitilakis, G.D. Manolis, I. Constantopoulos and I. Pasgianos, Seismic Hazard to Buried Lifelines, Proceedings of 10th European Conference on Earthquake Engineering, Vienna, Austria, Aug. 28 - Sept. 2, 1994, TU Wien Publication, 1994.

O. Klingmuller, D. Diamantidis, G.M. Manfredini, F. Zuccarelli, I. Constantopoulos, J. Nuyens, G.D. Manolis, I. Pasgianos, K. Pitilakis, D. Talaslidis and K. Makropoulos, Aseismic Design of Buried Lifelines, pp. 1121-1128, Vol. 2, Proceedings of 2nd International Conference on Earthquake Resistant Construction and Design, Edited by S. A. Savidis, Berlin, Germany, July 15-17, 1994, Balkema, Rotterdam, 1994. Klingmuller, D. Diamantidis, G.M. Manfredini, F. Zuccarelli, I. Constantopoulos, J. Nuyens, G.D. Manolis, I. Pasgianos, K. Pitilakis, D. Talaslidis and K. Makropoulos, Seismic Behaviour and Vulnerability of Buried Lifelines, Workshop on Collaborative European Research Activities for Seismic Risk Prevention and Reduction, ISMES S.p.A.-Seriate, Bergamo, Italy, November 9-11, 1994, EC Directorate General XII, Brussels, Belgium, 1994. G.D. Manolis, P.I. Tetepoulidis, D.G. Talaslidis and G. Apostolidis, Seismic Analysis of Buried Pipeline in a 3D Soil Continuum, Engineering Analysis with Boundary Elements, Vol. 15, 371-394, 1995.

PART I: OVERVIEW OF PAST WORK

The basic philosophy on design and performance of NG pipelines remains the same as in the past. What has changed since the 1970’s-1980’s, when basic research was done on soil-structure-interaction phenomena, is that we have much information on soil impedance functions and nonlinear soil behavior. What has changed since the 1980’s-1990’s, when basic research was done on numerical methods such as FEM and BEM, is that we have powerful and versatile FEM programs that can handle very large-scale problems involving thousands or even millions DOF. There is now much more emphasis than in the past on stochastic concepts comprising risk analysis, the introduction of fragility curves, and on the reliability of pipeline performance to environmentally-induced loads.

There is much more filtering of research work in contemporary design codes than in the past. This means design code updating is more frequent and practicing engineers need to upgrade their skills. The down side is design code complexity, which may cause over-conservative design. For instance, the current Greek code on building rehabilitation is so strict that it is impossible to find structures built before the 1990’s that can satisfy contemporary seismic performance issues.

PART II: DESIGN CONSIDERATIONS FOR NG PIPELINES Material and Thickness Determination for Strength and Rapture Route and Layout Internal Pressure External Pressure Thermal Loads Ground Failure Phenomena: Liquefaction, Landslide, Lateral Spreading, Gross Settlement Transient Loads: Earthquake-induced Motions, Hydrodynamic Effects Earthquake Fault Breakage Connections and Bends

PART III: LIST OF CONTEMPORARY DESIGN CODES AND STANDARDS

ASME B31.1, ASME Codes for Pressure Piping, American Society of Mechanical Engineers, 2001. ASME B31.3, Process Piping, American Society of Mechanical Engineers, 2002. ASMEB31.4, Pipeline Transportation Systems for Liquid Hydrocarbon and other Liquids, American Society of Mechanical Engineers, 2006. ASME B31.8, Gas Transmission and Distribution Piping Systems, American Society of Mechanical Engineers, 2007. CEN 234WG3-103, Pipelines for Gas Transmission, European Committee for Standardization, 1993.

CRF 192, Transportation of Natural and other Gas by Pipeline: Minimum Federal Safety Standards, Code of Federal Regulations, 2005. CRF 195, Transportation of Hazardous Liquids by Pipeline, Code of Federal Regulations, 2005. CSA-Z662-03, Oil and Gas Pipeline Systems, Canadian Standard Association, 2003. ISO 13623, Petroleum and Natural Gas Industries: Pipeline Transportation Systems, International Standards Organization, 2000. NEN 3650, Requirements for Steel Pipeline Systems, Canadian Standard Association, 2003. NPD, Guidelines to Regulations relating to Pipeline Systems in the Petroleum Activities, Norwegian Petroleum Directorate, 1990.

PART IV: HIERARCHY OF ANALYSIS METHODS

Mathematical Models 1D Generalized Beam Model:

Continuously-supported Beam Beam on Elastic Foundation Beam on Poroelastic Foundation

2D Plane Strain/Stress Discs: Hollow Ring with Internal/External Pressure

Plate and Shell Elements 3D Continuum

Numerical Methods of Analysis The Finite Element Method (FEM): General 1D, 2D, 3D Models for the Pipeline under any Type of Loading Conditions: Stress Analysis, Thermal Analysis, Buckling Load Computation, Eigenvalue Extraction, Transient Analysis The Boundary Element Method (BEM): Computation of Soil Impedances, Modeling of Semi-Infinite Media, Computation of Hydrodynamic Loads Hybrid Methods: FEM + BEM + FDM for Soil-Structure-Interaction Modeling and for Fluid-Structure-Interaction

PART V: LIMIT STATE BASED STRENGTH DESIGN Four limit states for pipeline design are identified: [1] Ultimate limit state (ULS), associated with single load application or overload situation: Bursting, local buckling and collapse. [2] Serviceability limit state (SLS), associated with possible failure but reduces the operational capability or utility of a pipeline. [3] Fatigue limit state (FLS), which is a ULS condition accounting for accumulated cyclic load effects: Ratcheting, global buckling and walking. [4] Accidental limit state (ALS) is a condition that, if exceeded, implies loss of structural integrity caused by accidental load: Accumulated plastic strain, strain concentration, accidental loads.

PART VI: SOIL-PIPELINE INTERACTION [1] Pipeline Penetration in Cohesive Soil [2] Pipeline Penetration in Non-cohesive Soil [3] Axial Load-Displacement Response of Pipelines [4] Lateral Load-Displacement Response of Pipelines [5] Seabed soil-pipe interaction affects:

On-bottom lateral stability of pipelines under hydrodynamic forces. Thermal expansion of pipelines and global buckling. Pipeline laying, bottom towing and pulling-in methods of installation. The touchdown point of the SCR design Pipeline spanning

PART VII: SEISMIC ANALYSIS & DESIGN ISSUES FOR PIPELINES

Buried pipelines conform to the motions of the surrounding soil so that the seismically-induced dynamic strains can be directly imposed of the continuous beam element modeling the pipeline. This is Newmark’s assumption dating 1959, and is basically a quasi-static approach as it ignores inertia effects.

Above-ground pipelines experience seismic motion at their support elements with the ground. Due to the large extent of the pipeline, seismic motion is not the same at all supports, which is the case of non-uniform ground motion.

This phenomenon may also due to the material inhomogeneity, namely spatially variable material properties (density and shear modulus), the presence of non-parallel layers, the presence of discontinuities such as geological cracks, cavities, solid inclusions, etc.

The possibility for the soil to exhibit non-linear behavior in the presence of strong ground motions must be considered. Interface phenomena between soil and outer pipeline surface may lead to separation effects in the axial and transverse directions. Global and local pipeline instability effects may be manifested, especially for soft or liquefiable soil. The change of direction of the pipeline leads to stress concentration phenomena at the bends. The same phenomenon may be manifested as the pipeline crosses geological fault lines. The presence of weak links in the segmented pipeline which are inevitable because of the presence of welded connections.

PART VIII: SEISMIC BASE ISOLATION ISSUES FOR PIPELINES Seismic isolation is a technology for reducing the effects of earthquake shaking on buildings, bridges and infrastructure (power plants, etc) in general. In general, the seismic isolation of pipelines is usually achieved with flexible piping joints made from high damping rubber, see figure below. The installation of seismic isolation devices on tanks can accomodate relative movements between the pipe-to-tank connections and pipe-to-ground anchors that are typically larger than the movements of the non-isolated systems. These movements usually exceed the natural flexibility of the pipeline and often causes local failure. The flexible joint systems can also be utilized to compensate for those movements to avoid overstressing of the pipe.

Figure 1: Pipeline with connections and bends (full scale)

PART IX: SECONDMENTS

1. A.A. Markou, post-doc associate at AUTH, March 2017-February 2018, NGI, supervised by Dr. A. Kaynia. Development and calibration of non-linear mechanical models for interface elements between pipeline and soil. Based on previous work for base isolation elements. These mechanical models can be re-structured for constructing interface elements for piles in soil. 2. A. Athanasiou, PhD candidate at AUTH, September2018-August 2019, possibly at Hochtief (?). Large scale FEM eigenvalue and transient analysis of pipeline crossing a 3D half-space. Based on previous SSI studies for nuclear power plants. The effect of pipeline bends, soil inhomogeneity and friction effects at the pipeline to soil interface will be studied. 3. S. Papadopoulos, PhD candidate at AUTH, 2019-2020 (?), non-uniform ground motion.

Non-linear interface elements for cyclic loading: (1) Bilinear mechanical model, two versions. (2) Trilinear mechanical model, two versions Analytical transient solutions, Newmark-beta numerical algorithms, energy methods. Shear behavior in 1D, effect of axial force. Calibration of the models is necessary from soil-pipeline experiments. Possible problems if experiments are not full-scale: scaling factors will require a much denser soil material, boundary conditions at the ends, energy radiation effects. Alternatively, one may use actual measurement data form operational pipelines, provided ground shaking takes place. The influence of the surrounding soil plays paramount importance in the presence of ground shaking, hence the need for detailed 3D soil-pipeline FEM models.

X. CLOSURE

What we propose is to develop general numerical models for the transient analysis of pipelines due to seismic load, focusing on relative motion between pipeline and soil, between pipeline segments and introducing high damping rubber bearing (HDRB) joints at select joints of the pipeline so as to ameliorate differential motion and overstressing effects. Our numerical results will be of interest in the development of an experiment testing on the stress development at a full-scale pipeline joint due to displacement-controlled input. The possibility of field measurements should also be considered. There is much uncertainty in the performance of these buried lifelines, both epistemic and aleatory. Hence the need to introduce probabilistic measures, as is done for instance in the life insurance business.

There has been much work on buried lifelines under naturally-induced hazards, but we are still a long way from comprehending and accounting for all possible problem parameters (if it is indeed possible). Most buried NG pipelines date from the 1940’s. In the US alone, there are more than 40,000 km of pipelines, much of it ageing and difficult even to for rudimentary SHM applications. As all infrastructure, so do NG networks have a useful life expectancy, and there must be provisions for replacement, much as is in the case for buildings. Design codes must remain relatively simple and minimalistic, and in the form of guidelines. It is impossible to codify all possible variations in a engineering problem as complex as buried lifelines. More advanced material can always be added in commentaries to the design codes. Resilience of NG pipeline networks is foremost a question of resources, namely how much effort and money is spent on the post-earthquake

recovery by the central and local governments. Managerial tools based on research are but one aspect of this effort. Partner AUTH will also be responsible for organizing an International Workshop within the framework of the 16th European Conference in Earthquake Engineering (16 ECEE) that will be held in Thessaloniki, Greece from 18-23 June 2018 to commemorate the 40th anniversary of the June 20, 1978 earthquake.

AUTH SECONDMENT FOR 2018

ALEXANDROS ATHANASIOU, PHD STUDENT (?)

NONLINEAR SOIL-STRUCTURE-INTERACTION (SSI): 3D FEM MODELS FOR NATURAL GAS PIPELINES

UNDER SEISMIC LOADS

I. THE TAP (TRANS-ADRIATIC PIPELINE) BENCHMARK PROJECT:MATERIAL PROPERTIES FOR THE SOIL AND PIPELINE

Two distinct types of soils are considered for the Lake Volvi region in N. GreeceUsing the Strata software, the properties of soil are determined after a 1Dequivalent linear analysis on the soil column to include soil non-linearitiesThe equivalent shear modulus G’ and damping factor D’ are computed as

Material properties of the steel pipeline from TAP data at https://www.tap-ag.grOverall dimensions: D = 1m, t=15mmD/t=66.65γ=78.5 kN/m3

Eeq=210,000,000 kPa

ν=0.2

For a transient analysis, it is necessary to consider Rayleigh damping as [C]=α [M] + β [Κ], built by matching the values of α and β from modal damping

SandG’=0.5GE’=234000kPaD’=9.5%

ClayG’=0.65GE’=1521000kPaD’=7.5%

The element size L of the FEM mesh from wave propagation considerations according to the expected frequency content of the seismic excitations is fmax = 2Hz, Vsmin = 200m/s --- Lmax = 10mThe max FE dimension chosen for this mesh is L max=5m

II. FEM MODEL MESH DIMENSIONING

Element typesModal Analysis (quadratic finite elements):Shell -> S8R, 3D Stress ->C3D20R (more integration points – nodes between)Transient Analyses (linear finite elements):Shell -> S4R, 3D Stress ->C3D8R Boundary ConditionsGravity step: Bottom fixed node displacements (Ux,y,z=0), gravity stepAcceleration step: Imposed acceleration on bottom nodes parallel to the pipeline, Ax=amplitude, Uy=0 and Uz=0Side nodes pinned (master, slave), pure shear between vertical soil FE levelsInterface between pipeline and soil: “welded” in modal and linear analysis, use of contact property in transient nonlinear (NL) analysisOnly in NL analysis: Rollers at the end nodes of the pipeline

III. FEM MODEL AND MESHING

Gravity step: Imposed gravity acceleration on all finite elementsPressure step: Imposed pressure on pipeline according to TAP (2015)Pressure Value -> 9500kPa or 9.5 mPa, a high pressure NG pipeline

Acceleration Step: Ricker-type wavelets

IV. LOADS

-0.20

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0 1 2 3 4 5

Acce

lera

tion

(m/s

2 )

Time (Sec)

Ricker Wavelet (Mexican Hat)

Frequency range: 0.5Hz to 4Hz at 0.5 step incrementsTotal -> 8 excitationsSeismic load multiplier: Thessaloniki, Greece -> Zone II (0.24g=2.354 m/sec2), according to Eurocode 8

Soil deposit only Soil deposit with pipeline

1st and 2nd translational mode eigenfrequencies: f1,2=2.22 Hz

1st and 2nd translational mode eigenfrequencies: f1,2=2.21 Hz

Simple shear wave propagation calculation (without reduction):f=Vsi mean / 4Hi = 2.81 Hz

V. MODAL ANALYSIS

• TIE constraint between pipeline and soil that corresponds to welded continuity

Gravity step: Static -> self weight Pressure step: Static -> inner pressure in pipelineAcceleration step: Excitation applied at bottom nodes in the X horizontal direction with Δt=0.05 sec, output every 0.05 secBoundary conditions: Weld contact connection along the pipeline length. Essentially, pipeline conforms to the soil deformation (Newmark’s assumption)

VI. LINEAR TIME HISTORY ANALYSIS

Contact properties:“Penalty” tangential motion, “Hard” normal motion (no separation) This results in what is essentially a sliding connection

Threshold value to avoid sliding is controlled by the interface friction coefficients (static and dynamic values) -> μ

VII. GEOMETRICALLY NON-LINEAR BOUNDARY CONDITIONS

VIII. GEOMETRICALLY NON-LINEAR BC VALUES

Friction factor between soil and pipeline: American Lifeline Alliances (ALA, 2001) - ASCE

We used f=0.8 (rough steel coating)and φ=33ο for SM,SM-SC,ML(from Raptakis et al., 2006)

δ=26.4ο

μ=tan(δ)=0.5

Input: Acceleration imposed at base, direction parallel to X axis

Number of analyses: 8 linear and 8 non-linear in the frequency range 0.5 – 4.0 Hz in increments of 0.5

Computed data: Hoop stresses σθθ -> Critical for design (ALA, 2001) derived from Abaqus Stress = S22 component for shell elements

Plot: Dimensionless result as ratio of hoop stress to EC8 Limit Design Stress

Limit strain ε=1%Modulus of elasticity E=210 GPaσ EC8 = Ε * ε = 2100 MPa

IX. GEOMETRICALLY NON-LINEAR ANALYSIS

0 1 2 3 4 5 6 70

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Time(sec)

Stre

ss R

atio

σ22

/ σ E

C8

Stress Ratio vs Time of Node 8

Non LinearLinear

X. RESULTS (AT A SINGLE NODE)

0 1 2 3 4 5 6 7-4000

-2000

0

2000

4000

6000

8000

10000

Time(sec)

Stre

ss σ

22 L

inea

r - S

tress

σ22

Non

Lin

ear (

kPa)

Stress (L-NL) vs Time of Node 8

X. RESULTS (SINGLE NODE)

0 1 2 3 4 5 6 7-0.002

-0.001

0.000

0.001

0.002

0.003

0.004

Time(sec)Stre

ss σ

22 L

inea

r - S

tress

σ22

Non

Lin

ear /

σE

C8 Stress (L-NL) vs Time of Node 8


0.5cm max sliding for 0.5Hz at node 8

0 1 2 3 4 5 6 7-0.002

-0.001

0.000

0.001

0.002

0.003

0.004

0.005

Time(sec)

Rel

ativ

e D

ispl

acem

ent S

oil -

Pip

e (m

)

Relative Displacement - 0.5Hz


0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0.5 1 1.5 22.5 3

3.5 4

σ/σ E

C8

Frequency (Hz)

Non Linear

Linear

Stress mitigation for frequency range 0.5-4Hz

Comment: About a 1% reduction at every frequency

X. FINAL RESULTS

REFERENCES

ABAQUS (2003), Analysis User’s Manual, Version 6.4, Pawtucket, Rhode Island, USAANSYS (2008), Structural Mechanics Finite Element Software, Version 10.0, Canonsburg,Pennsylvania, USAQ. Bai and Y. Bai, Subsea Pipeline Design, Analysis and Installation, Elsevier, Oxford, UK, 2014P.S. Bulson, Buried Structures: Static and Dynamic Strength, Chapman and Hall, London, 1985S. K. Chakrabarti, Dynamics of Floating Offshore Structures, World Scientific Publishing, Oxon,UK, 2014J.J. Johnson, Soil-Structure-Interaction: The Status of Current Analysis Methods and Research,Nuclear Regulatory Commission Research Report NUREG CR-1780, Washington D.C., 1981Y.C. Kim, Handbook of Coastal and Ocean Engineering, World Scientific Publishing, Oxon, UK,2009B. M. Sumer, Liquefaction around Marine Structures, World Scientific Publishing, Oxon, UK,2014

AUTH SECONDMENT FOR 2017

ATHANASIOS A. MARKOU NORWEGIAN GEOTECHNICAL INSTITUTE (NGI)

OSLO N-0855, NORWAY

NONLINEAR INTERFACE MECHANICAL MODELS FOR NATURAL GAS PIPELINES UNDER SEISMIC LOADS

OUTLINE

High damping rubber bearing isolators are used for the seismic isolation of structures worldwide for well over thirty years. We present the adaptation of mechanical models currently available for the simulation of the compressive/shear response of these isolators for constructing interface elements between an NG pipeline and the surrounding soil as well as connection elements in the presence of ground motions induced by seismic events. Given the complex and possibly nonlinear behavior of the pipeline-soil interface, no model is able of capturing every single aspect of this dynamic response. Some issues and uncertainties involved in the characterization of this behavior are (1) Coupled bidirectional horizontal ground motion (2) Coupling of vertical and horizontal motions (3) Strength and stiffness degradation during loading cycles (4) Variation in the ground motion along the length of the pipeline (4) Variation in the critical buckling load capacity of the pipeline due to lateral displacements.

Fig. 1. LNG pipeline and aboveground connections

INTERFACE ISOLATION SYSTEM MODELLING ISSUES The best-known model for simulating the hysteretic behavior of structural components is the bilinear hysteretic model (BHM). There are two possible mechanical formulations that correspond to the same bilinear model from a mathematical viewpoint. The first one (BHM1) consists of a linear elastic spring connected inseries with a parallel system comprising a plastic slider and a linear elastic spring, while the second one (BHM2) comprises a linear elastic spring connected in parallel with an elastic-perfectly plastic system. However, the bilinear hysteretic model is unable to describe either softening or hardening effects, and has therefore been extended to a trilinear model. There are two trilinear hysteretic models (THM) that exhibit a total of three plastic phases. More specifically, the first model (THM1) exhibits one elastic phase, while the second (THM2) one exhibits two elastic phases according to the strain amplitude level that develops during loading. Additionally, the change of slope between the plastic phases in unloading does not occur at the same displacement level in the two models.

Furthermore, in THM1 the dissipated energy per cycle, decreases in the case of hardening and increases in the case of softening, while in the THM2 the dissipated energy per cycle remains unchanged, as is the case with the bilinear models. All hysteretic models are solved analytically and calibrated against free vibration test results. Based on the THM1, a numerical time-stepping method is developed based on the original Newmark’s method for constant accelerations combined with Newton-Raphson iterations. This is a necessary step, because more generalized hysteretic models cannot in general be solved analytically. Finally, this numerical solution capability will allow for extension of the THM to bi-directional horizontal motion and to time-varying vertical loads, where only numerical solutions will be possible.

Fig. 2. Single-degree-of-freedom (SDOF) representation of the hysteretic interface

Fig. 3. The (a) BHM1 and (b) BHM2 mechanical representations

Fig. 4. The (a) THM1 and (b) THM2 mechanical representations

REFERENCES ASME B31.4, Pipeline Transportation Systems for Liquid Hydrocarbon and other

Liquids, American Society of Mechanical Engineers, 2006. A.A. Markou, G.D. Manolis, Mechanical formulations for bilinear and trilinear hysteretic

models used in base isolators. Bull. Earthquake Engng 14, 3591-3611, 2016. A.A. Markou, G. Oliveto, A. Athanasiou, Response simulation of hybrid base isolation

systems under earthquake excitation, Soil Dynamics Earthquake Engineering Vol. 84,120-133, 2016.

A. A. Markou, G. Oliveto, A. Mossucca and F.C. Ponzo, Laboratory experimental tests on elastomeric bearing from the Solarino project. Progetto di Ricerca DPC–RELUIS, Linea di Ricerca 6: Isolamento e Dissipazione, Coordinatori: Ponzo FC and Serino G, University of Basilicata, Italy, 2014.

T. Ray, A.A. Sarlis, A.M. Reinhorn, M.C. Constantinou, Hysteretic models for sliding bearings with varying frictional force, Earthquake Engineering Structural Dynamics, Vol. 42, 2341-2360, 2013.

MECHANICAL MODELS FOR HDRB

Table 1: THM1 Formulation and Mechanical Parameters

MECHANICAL MODEL VALIDATION

The 3rd cycle of a set of cyclic shear tests on a commercial HDRB isolator saved from the Solarino building project (2006) were conducted at the University of Basilicata in Italy (2016) 10 years later and were used for the parameter identification of the BHM and THM. The geometrical characteristics of the tested HDRB isolator are given in Table 2. The cyclic shear tests were conducted under a compressive stress of 6 MPa and at a frequency of 0.5 Hz, for 10 different shear strain amplitudes varying from γ=0.05 - 2.00. In parallel, cyclic tests at different strain amplitudes (γ=1.20 and γ=2.00) and at variable frequencies (from 0.006 Hz to 0.83 Hz) were implemented to investigate the effect of rate-dependence of the bearings. The tests showed that the HRDB isolator can be assumed rate-independent in this frequency range.

The total number of parameters for the THM1 system is 33 and the identification error is rather small at e2=2.5%. The total number of parameters of the THM2 system is 30, and the identification error is e2=5.0%, twice that of the THM1 system.

Fig. 5. THM1 computed response compared with experimental data

Fig. 6. THM2 computed response compared with experimental data

Fig. 7. Details of strain softening – hardening response for all models

DEVELOPMENT OF A NEWMARK ALGORITHM FOR HYSTERETIC MEDIA It is concluded that the well-known BHM are replaced by the more accurate THM models for describing the response of hysteretic material interfaces under cyclic loading. Next, a Newmark’ time-stepping method with the Newton-Raphson iterative technique is developed for the numerical solution of the more accurate THM1 model.

Newmark’s Method for an SDOF System representing a HDRB

(1) The stiffness that is used to guess the force for the candidate displacement will always be the largest stiffness in the system, namely the elastic stiffness (k0). Once the force is calculated with the use of the elastic stiffness, there is a need to check if this force is correct. (2) In order to check the force that develops, we need to define two limit (or bound) curves

Fig. 8. Upper and lower bound curves for the THM1

COMPARISON STUDIES

Table 2: The Solarino HDRB isolator: Testing and identification from free vibration tests

The equation of motion for the SDOF system representing a HDRB isolator is derived from the THM1 model. It is solved both analytically in closed form and numerically by the modified Newmark method. The equation of motion is

𝑚𝑚��𝑢(𝑡𝑡) + 𝑐𝑐��𝑢(𝑡𝑡) + 𝑓𝑓𝑇𝑇𝑇𝑇𝑇𝑇 + 𝑓𝑓𝐿𝐿𝐿𝐿𝐿𝐿𝑇𝑇 = 𝑝𝑝(𝑡𝑡) and the ground excitation is a simple sinusoidal motion in the form

𝑝𝑝(𝑡𝑡) = −0.25𝑚𝑚𝑚𝑚 ∙ sin (2𝜋𝜋𝑓𝑓) where m is the mass, g=9.81 m/sec and the is f=0.41 Hz is vibration frequency The result agreement is extremely good. For instance, the maximum displacements registered for the base isolated structural system during the steady-state part of the response, which would be a design value, is 237 mm and 237.2 mm for the analytical and numerical solutions, respectively.

Fig. 9. (a) Force-displacement plot of the THM and displacement-time history of the SDOF model

Fig. 10. Force-displacement plot of the LCFM component and velocity-time

history of the SDOF model

Fig. 11. Force-displacement plot of the LVD component and acceleration-time

history of the SDOF model

EXCHANGE-RISKProgress at UoP

Prof. Stathis Bousias

Secondments• WP3: ESR6 - K. Tryfonos, PhD candidate, 12 months to

UoT. Starting date: Sept. 5, 2017”Experimental testing of burried pipelines”

• WP7: ESR24 – C. Thanopoulos, PhD candidate, 12 months to VCE. Starting date: July 2, 2017“Study the state-of-the-art on procedures for post-hazard rating of pipelines and investigate their implementation into a Decision Support System for Rapid Pipeline Recovery”.

• WP7: ESR23 – P. Katsimpini, PhD candidate, 6 months to Hochtief. Starting date: Sept. 2018.a

• “Investigation of alternative means for monitoring & inspecting pipes from energy storage facilities”

• Box: Height 1.15 m, Length: 1.20 m, Thickness: 0.20 m• Pipe (steel with flexible “sheeting”-coating: rubber band),

outside diam: D ~ 0.11 m• Uniaxial (X + Y) – Biaxial – Cyclic• Similitude: add vertical load

via airbags (?)• Rubber “sleeve” between the pipe

and the box (tyre-type tube)• External box-stiffeners

Research of ESR6 - UoT

Lateral (Pu) Vertical Bearing (Qd) Vertical Uplift (Qu)

Force Demand 3.90 KN 11.84 KN 0.97 KN

Force Capacity 30 KN 45 KN 45 KN

Displacement Demand 17.1 mm 11.4 mm 8.25 mm

Actuator Stroke 38.1 mm 25.4 mm 25.4 mm

Actual Stroke 20 mm 20 mm 20 mm

5D

5D

Φ120

8.5D-16D

Vertical fixity

Horizontal Load

φ=30, 33 & 36οΕ=3 & 5 ΜPa

σv=25, 50 & 100 kPa

Subsidence 35% of Ux, maxUplift 17% of Ux, max (8.5D)

Ux, max

Vertical Reaction = 25% of horizontal load

Shear Strains

8 9 10 11 12 13 14 15 16 1718

20

22

24

26

28

With Vertical Fixity

10%

7%

11%

Ε=3MPa, φ=36ο

P 10mm (kN)

Distance to Boundary (Diametre)

σv=25 kPa σv=50 kPa σv=100 kPa

8 9 10 11 12 13 14 15 16 17100

102

104

106

108

110

112With Vertical Fixity

Ε=3MPa, φ=36ο

P 10mm / P 1

0mm, 16D (%

)

Distance to Boundary (Diametre)

σv=25 kPa σv=50 kPa σv=100 kPa Average

Future research• Tests for indicative failure modes:– Not replicating past tests– Represent the :• parameters involved, e.g. actual D/t ratio, internal

pressure, etc., at as large scale as possible• basic failure mechanism expected during the

distributed HS– Consultation with Prof. S. Karamanos

(member of the Scientific Advisory Board)

Hybrid Simulation ….• Under discussion …

Soil-pile interaction phenomenaExchange-Risk WorkshopFrankfurt, September 1, 2017

Amir M. KayniaDiscipline Lead, Vibration and Earthquake Eng., NGI

Athanasios A. MarkouPostDoctoral Researcher, NGI

Outline

Lab experiments on soil-pipe interaction in University of Bristol by Rebecca C. Stubbs

Constitutive modelling for soil material

Studying soil-pipe interaction phenomena

Lab experiments of pipeline in loose sand

Force - displacement curve for loose sand (a) force-horizontal displacement (b) vertical displacement-force at different depths

Lab experiments of pipeline in dense sand

Force - displacement curve for dense sand: force-horizontal displacement (left) vertical displacement-force at different depths (right)

Mechanical models for soil-structure interaction

Trilinear Hysteretic Model (THM) consists of 3 elements:1. Linear elastic spring2. Plastic slider3. Trilinear elastic spring

Accounts for:1. Lower energy dissipation while hardening2. Higher energy dissipation while softening

Mechanical model #1 for HDRBs

Combination of Trilinear Hysteretic Model (THM) with Trilinear Elastic Model (TEM) allows for:1. Control of energy dissipation2. Keeping constant loading curve

Calibration of mechanical models to lab data

-40 -20 0 20 40-3

-2

-1

0

1

2

3

Typical generalized model proposed by Iwan 1967 that accounts for high equivalent viscous damping ~60%


-40 -20 0 20 40-3

-2

-1

0

1

2

3

Generalized model composed by THM that allows for control over viscous damping and shape of loops


Modeling soil strain softening

-40 -20 0 20 40-6

-4

-2

0

2

4

6


Modeling soil strain softeningUnder development

-40 -20 0 20 40-6

-4

-2

0

2

4

6

Effective stiffness and equivalent viscous damping ratio

10 -1 10 0 10 1 10 20

0.2

0.4

0.6

0.8

1

10 -1 10 0 10 1 10 20

20

40

60

Control over damping under the same effective stiffness

Thermal expansion of pipelines─ Lateral buckling for unburied pipelines (main focus of offshore division)─ Upheaval buckling for buried pipelines

Initial pipe-lay─ Vertical penetration due to static (catenary) forces─ Additional embedment from cyclic action─ Axial and lateral resistance (e.g. for curves)

Seismic response(this presentation)

Typical geotechnical pipeline issues

Pipeline temperature changes during lifetime, resulting in expansion and contraction.

Due to axial soil-pipe restraint, pipeline may buckle laterallyTesting recommended to investigate soil-pipe resistance in both axial (lengthways) and lateral (sideways) directionsResults used to design countermeasures

Axial restraintLateral buckle

Thermal expansion of unburied pipelines

Lateral buckling – overview

• Use consistent set of acceleration time histories at all points along pipeline.

Dynamic approach (Example: hopefully Shah Deniz)

0 10 20 30 40-0.5

0

0.5

1

1.5

2

2.5

Dynamic time [s]

Horizontal displacement, Ux [m]

Displ.

Point 1

Point 2

Point 3

Point 4

Point 5

Point 6

Point 7

Point 8

Point 9

Point 10

0 10 20 30 40-1.2

-0.8

-0.4

0

0.4

Dynamic time [s]

Vertical displacement, Uy [m]

Displ.

Point 1

Point 2

Point 3

Point 4

Point 5

Point 6

Point 7

Point 8

Point 9

Point 10

0

5

10

15

20

25

0 1 2 3 4 5

τ (k

Pa)

Strain (%)

Traditional Soil springs

Strain-softening Soil springs

Lateral buckling – typical response

Capturing of hardening effects of soil-pipe phenomena

-100 -50 0 50 100-5

0

5

Capturing of hardening effects of soil-pipe phenomena

-100 -50 0 50 100-5

0

5

Thank you for your attention

19

Report about activities of the team fromBauhaus-Universitat Weimar

Institute of Structural MechanicsBauhaus-Universitat Weimar

Dr.-Ing. Volkmar ZabelProf. Dr.-Ing. habil. Carsten Konke

Abinet HabtemariamMarcelo Bianco

1st September 2017

Research stays Research report Perspective secondments

Previous secondments

Secondment from 19th Sept. to 19th Oct. 2016 at VCE in Vienna

State-of-the-art report: Inspection and monitoring for life-cyclemanagement of natural gas pipelines extending previous work by N.Psyrras

Description of damage modes to be detectedTechnologies for inspection and monitoring of pipeline systemsPipeline monitoring for operation support and risk management

Review paper for Journal submission still in internal revision

2 / 14


Considerations on numerical models of pipelines

Failure mechanism of continuous buried steel pipelines

Local bucklingTensile fractureUpheaval bucklingCross-section distortion

Numerical simulation of pipelines

Beam (limitation with respect to failure description)Shell (numerical description of failure much better, but very largemodel dimensions → computationally expensive)GBT (extends beam theory and allows for description of cross-sectionaldeformations → computational efficient)

3 / 14


Generalized Beam Theory (GBT)

The steps involved in the application of either first or second order GBTanalysis are twofold, 1

1 A cross-section analysis: identifies the cross-section deformationmodes and determines the corresponding modal properties. Itsperformance does not involve the member length, support conditionsor applied loads.

2 A member analysis: is concerned with the assembly and solution ofthe member differential equilibrium equations and boundaryconditions, from knowledge of;

1 The cross-section geometrical properties.2 The member material properties.3 Its length and support conditions.4 The applied load.

1Silvestre, Nuno, and Dinar Camotim. GBT buckling analysis of pultruded FRPlipped channel members. Computers and structures 81.18 (2003): 1889-1904..aaaaaaaaaaaaaaaaaaa 4 / 14


Deformation ModesWarping functions (Einheitsverwolbungen)

Cross sectional deformation mode can be defined with two orthogonalwarping function;

ku =

{r cos mϑ if m = (k − 1)/2 for k = 1, 3, 5....r sin mϑ if m = k/2 for k = 2, 4, 6....

kv = −ku/r kw = ku/r (1)

Figure: Local and global Coordinate system for thinwall cylinder section.

5 / 14


Implementation of GBT Linear case

Figure: Flow chart for programing the GBT linear case.

6 / 14


Implementation of GBT Linear case

Figure: Flow chart for programing the GBT linear case.

7 / 14


Example GBT Linear Case

Figure: Bending deformation of a simply supported pipe beam.

8 / 14


Example GBT Linear Case

Figure: Bending deformation of a fix supported pipe beam.

9 / 14


Shell Model Vs GBT

Comparison

Shell model800 Elements816 NodesMatrix size 4896

GBT model20 Elements21 Nodes4 Mode shapesMatrix size 84

10 / 14


Non-linear GBT Analysis

In order to consider geometrical non-linearity it is necessary todetermine the total stiffness matrix which is the sum of elastic, initialdeformation and initial stress stiffness matrix.

K = Ke + Ku + Kσ (2)

Where:Ke is the global stiffness matrix that defines the stiffness of thestructure.Ku is the initial displacement matrix that accounts for the change instiffness that comes from the displacements.Kσ is the initial stress stiffness matrix that accounts for themembrane forces effect on the stiffness.

11 / 14


Combination of Different Modes

Figure: X kij matrix, which shows the initial stress in mode k will link thedisplacement in mode i with the force in mode j as well as,

displacement in mode j with the forces in mode i .

12 / 14


Outlook

Development of geometrically and physically nonlinear analysis

Implementation of explicit dynamic analysis

13 / 14


Perspective secondments

Contribution to WP3: 3D numerical simulation of soil-pipelineinteraction

Late autumn 2017, winter 2017/18:

Abinet Habtemariam (for 3 months) and Marcelo Bianco (for 3months) visit VCE to

Exchange experience about numerical modelling of pipe structures andsimulationContinuation of development of geometrically and physically nonlinearanalysisImplementation of explicit dynamic analysisVerification and validation with a suitable case study

14 / 14

Xenia Karatzia, Robert Borsutzky 1. September 2017 1

INTERACTION EFFECTS BETWEEN BUILDINGS

AND UNDERGROUND LIFELINE STRUCTURES

UNDER SEISMIC EXCITATION

XENIA KARATZIA

ROBERT BORSUTZKY

HOCHTIEF Engineering Consult IKS

EXCHANGE-RISK WORKSHOP 2017


Effect of massive rigid structures on relatively soft

underground structures (pipelines / channels) under seismic

excitation

The construction of a new building

may cause differential shifts along the lifeline due to local

“disturbance„

imposes its dynamic behavior to the surrounding soil and

the lifeline embedded in it

causes complex interaction involving the soil and the two

structures during seismic excitation

RESEARCH OBJECTIVE



Luco & Contese (1973) Structure-Soil-Structure-Interaction

(SSSI) or Dynamic Cross Interaction (DCI) (based on publications

about Nuclear Power Plant), analytical solution

Jiang & Yan (1998) Interaction between two adjacent buildings

Olliff et al (2001) Soil-Structure-Pipe-Interaction, ground

movement induced failures

Calvetti et al (2004) Soil-pipe interaction, Distinct Element

Method

Borsutzky et al (2011) SSSI-Interaction, seismic behavior of

neighboring buildings, Thin-layer Method coupled with FE

Lou et al (2011) SSSI: Literature review, inspection of the

commonly used numerical methods & computer codes

LITERATURE REVIEW



Wang et al (2013, 2017) Interaction between underground &

ground structure

Abate & Massimino (2016) Tunnel–Soil–Structure Interaction

(full-coupled system)

Trautmann & O` Rourke, Trautmann et al (1985) Lateral & uplift

force-displacement response of buried pipes, experiments

Marshall et al (2010) Tunneling beneath buried pipelines

(centrifuge tests)

Robert et al (2016) Lateral load-displacement behavior of

pipes, Full-scale tests

Aldaikh et al (2016) SSSI: Shake table testing

Dashti et al (2016) Centrifuge models of underground

structures near tall buildings

LITERATURE REVIEW



LITERATURE REVIEW


Methods of analysis:

Analytical or Semi-analytical (solid or beam

element, strip foundation, cylindrical shells)

Numerical (FE, BEM, FE-BEM, FDM, DEM, Thin-

layer Method)

Experimental (shake table, centrifuge & full scale

tests)

Soil-Pipe interaction

Analytical or Semi-analytical (Poulos 1974, Moore 1987,

Rajani & Morgenstern 1993, Kouretzis et al 2015, Guha et al 2016,

Karamitros et al 2016)


s

h

structure

pipeline d

H

Control points

b

y

PROBLEM DEFINITION


Case 1 Case 2

s

h

b

structure II

pipeline

structure I

d

H

Control

points

y


PROBLEM DEFINITION


s

c

b

pipeline

structure I L

L >> c

s

c

b

channel

L

L c

structure II structure I

structure II

EI

EI


PROBLEM DEFINITION


The seismic behavior of each system will be investigated in

terms of :

Acceleration time-histories (control points)

Fourier amplitude spectra (control points)

Response spectra (control points)

Amplification ratios

Maximum pipe deflections &

Bending moments


PROPOSED METHODOLOGY


Thin-layer Method (implemented in code

BAUBOW) coupled with Finite Element Method

BAUBOW

Kinematic interaction:

Determination of

Foundation Input Motion

Determination of

impedance (stiffness &

damping) functions

SAPC

Dynamic analysis (in

frequency domain) considering

soil-structure-interaction (FIM &

impedance functions)

Determination of transfer

functions

Response

spectra


PROPOSED METHODOLOGY


Finite Element Method (PLAXIS 3D)

Settlement and bearing capacity analysis for onshore infrastructure

like petrochemical plants or liquefied natural gas (LNG) storage tanks

Application in onshore and offshore pipeline movement and stability

under various applied loading conditions

Advanced material models accounting for different loading conditions

of the soil encountered in excavation and foundation works (Mohr-

Coulomb, Hardening soil, soft soil, soft soil creep model)

Staged construction

Dynamic soil structure interaction

Dynamic loading by importing real earthquake signals

Various model boundary conditions (viscous, free-field and compliant

base boundaries)


WORK PLAN


1. HOCHTIEF-research report

2. Journal paper (SDEE)

14/8/2017 13/4/2018

DELIVERABLES


REFERENCES


1. Luco, Juan & Contesse, Luis. (1973). Dynamic structure-soil-structure interaction. Bulletin of the Seismological Society of

America. 63. 1289-1303.

2. L Olliff, J & J Rolfe, S & Wijeyesekera, Devapriya & T Reginold, J. (2001). Soil-Structure-Pipe Interaction with Particular

Reference to Ground Movement Induced Failures. Proc. of Plastic Pipes XI, 3-6 September, Munich, German

3. Calvetti, F & di Prisco, C & Nova, R. (2004). Experimental and Numerical Analysis of Soil–Pipe Interaction. J of Geotech and

Geoenv Eng. 130. 1292-1299. 10.1061/(ASCE)1090-0241(2004)130:12(1292).

4. Marshall, A & Klar, A & J. Mair, R. (2010). Tunneling beneath Buried Pipes - A View of Soil Strain and Its Effect on Pipeline

Behavior. J of Geotech & Geoenv Eng. 10.1061/(ASCE)GT.1943-5606.0000390.

5. Borsutzky R, Sadegh-Azar H. & Hartmann H.-G. (2011). Influence of neighboring buildings on the seismic oscillation

behavior. 12 D-A-CH Tagung – Erdbeben & Baudynamik, C. Koenke (Hrsg.), 15-16 September, Hannover, Germany (in

German)

6. Lou, Menglin & Wang, Huaifeng & Chen, Xi & Zhai, Yongmei. (2011). Structure–soil–structure interaction: Literature review.

Soil Dyn & Earthq Eng. 31. 1724-1731. 10.1016/j.soildyn.2011.07.008.

7. Wang, H & Lou, M & Chen, X & Zhai, Y. (2013). Structure–soil–structure interaction between underground structure and

ground structure. Soil Dyn & Earthq Eng. 54. 31–38. 10.1016/j.soildyn.2013.07.015.

8. Wang, H & Lou, M & Zhang, R. (2017). Influence of presence of adjacent surface structure on seismic response of

underground structure. Soil Dyn & Earthq Eng. 100. 131-143. 10.1016/j.soildyn.2017.05.031.

9. Abate, G & Massimino, M. (2017). Numerical modelling of the seismic response of a tunnel–soil–aboveground building

system in Catania (Italy):. Bulletin of Earthq Eng. 15. 469-491. 10.1007/s10518-016-9973-9.

10. Trautmann, C & D. O'Rourfce, T & H. Kulhawy, F. (1985). Uplift Force-Displacement Response of Buried Pipe. J of Geotech

Eng. 111. . 10.1061/(ASCE)0733-9410(1985)111:9(1061).

11. Trautmann, C & D. O'Rourke, T. (1985). Lateral Force-Displacement Response of Buried Pipe. J of Geotech Eng. 111. .

10.1061/(ASCE)0733-9410(1985)111:9(1077).



12. Robert, D.J. & Soga, K & O’Rourke, T.D. & Sakanoue, T. (2016). Lateral Load-Displacement Behavior of Pipelines in

Unsaturated Sands. J of Geotech and Geoenv Eng. 142. . 10.1061/(ASCE)GT.1943-5606.0001504.

13. Aldaikh, H & Alexander, N & Ibraim, E & Knappett, J. (2016). Shake table testing of the dynamic interaction between two and

three adjacent buildings (SSSI). Soil Dyn & Earthq Eng. 89. 219–232. 10.1016/j.soildyn.2016.08.012.

14. Dashti, S & Hashash, Y & Gillis, K & Musgrove, M & Walker, M. (2016). Development of Dynamic Centrifuge Models of

Underground Structures near Tall Buildings. Soil Dyn & Earthq Eng. 10.1016/j.soildyn.2016.04.014.

15. Poulos, H. G. (1974). Analysis of longitudinal behavior of buried pipes. Proc., Conf. on Analysis and Design in Geotechnical

Engineering, ASCE, Austin, Tex., 189–223.

16. D. Moore, Ian. (1987). Response of Buried Cylinders to Surface Loads. Journal of Geotechnical Engineering. 113.

10.1061/(ASCE)0733-9410(1987)113:7(758).

17. B. Rajani, B & R. Morgenstern, N. (1995). Pipelines and laterally loaded piles in an elastoplastic medium. Journal of

Geotechnical Engineering. 121. .

18. Kouretzis, George & Karamitros, Dimitris & Sloan, Scott. (2015). Analysis of buried pipelines subjected to ground surface

settlement and heave. Canadian Geotechnical Journal. 52. 1058-1071. 10.1139/cgj-2014-0332.

19. Karamitros, D & Zoupantis, C & Bouckovalas, G. (2016). Buried pipelines with bends: Analytical verification against

permanent ground displacements. Canadian Geotechnical Journal. 53. . 10.1139/cgj-2016-0060.

20. Guha, I & Randolph, M & White, D. (2016). Evaluation of Elastic Stiffness Parameters for Pipeline–Soil Interaction. J of

Geotech & Geoenv Eng. 142. 04016009. 10.1061/(ASCE)GT.1943-5606.0001466.

21. Buckingham, E. (1914). “On Physically Similar Systems; Illustrations of the Use of Dimensional Analysis”, Physical Review,

4, 345-376.

22. Poulos, H. G., and Davis, E. H. (1980). Pile foundation and design, Wiley, New York.

LITERATURE

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