Skip to main content

EXperimental Computational Hybrid Assessment of Natural Gas pipelines Exposed to Seismic Risk

Periodic Reporting for period 2 - EXCHANGE-Risk (EXperimental Computational Hybrid Assessment of Natural Gas pipelines Exposed to Seismic Risk)

Reporting period: 2018-01-01 to 2019-12-31

• What is the problem being addressed?
During the last decades, the overall exposure to seismic risk has increased not only due to the higher population density but also due to the more challenging construction methods and the multilayered connection between the various urban socio-economic activities. Within the built environment, the energy transportation systems, despite their structural simplicity, are one of the weakest links in terms of seismic safety. This is because their potential failure or loss of serviceability can have a disproportional direct and indirect socio-economic impact. Damage to pipelines, has also a transnational dimension, since there are no political boundaries in natural disasters: consequences in one region can propagate to other regions and affect millions of people. This spatial dimension of seismic risk, which is propagated by the interdependency of energy network operation, is poorly accounted for in risk assessment primarily due to the absence of a comprehensive and integrated resilience methodology and the lack of a joint strategy for risk management.

• Why is it important for society?
Energy production, preservation and safe transportation is one of the top priorities at a European level. Natural gas, in particular, has a key role in the future of energy supply for the E.U. with a growth anticipated to rise from currently one fifth, to one third of total energy supply within the next 25 years. Alternative transportation routes are also of major significance, as they cross areas of substantially different levels of seismic hazard. From these premises, arises the need to eliminate the probability of occurrence of a potential seismically induced failure (i.e. related to explosion, fire, leakage etc) that would not only have devastating environmental impact in the affected areas, but could also cause operation disruptions with equally significant socio-economic consequences throughout Europe.

• What are the overall objectives?
EXCHANGE-Risk is an Intersectoral/International, Research and Innovation transfer scheme between academia and the industry in Europe and North America focusing on mitigating Seismic Risk of buried steel pipeline Networks that are subjected to ground-imposed permanent deformations. It aims in developing a (nearly real time) Decision Support System for the Rapid Pipeline Recovery to minimize the time required for inspection and rehabilitation in case of a major earthquake. EXCHANGE-Risk involves novel hybrid experimental and numerical work of the soil-pileline system integrated with innovative technologies for rapid pipe inspection. The outcome of the project is a series of well targeted exchanges between the partners and ensures transfer of knowledge between the academia and the industry.
WP1: A comprehensive state-of-the art was produced by N. Psyrras (seconded from UBristol to UToronto) that led to a journal publication in Soil Dynamics and Earthquake Engineering (slide2.jpg).

WP2: This WP covers the experimental tests in Bristol, Tornoto and Patras. First, an experimental setup was constructed at UBristol to study the in-plane stiffness of the soil-pipe system (slide 8.jpg). K. Tryfonos (slide 9.jpg) who was seconded from UPatras to UToronto developed a setup to study the same problem with an alternative manner to consider the cyclic nature of earthquake loading (slide 09.jpg). G. Baltzopoulos, seconded from UNaples to UToronto developed a low-power actuator and wrote the software for the controller (slide 05.jpg). It is noted that the latter is not a contractual obligation and was produced as an additional output.

WP3: H. Stutz (slide12.jpg) who was seconded from UKiel (CAU) to VCE developed a preliminary finite element model for pipeline-soil interaction. A. Markou (slide13.jpg) seconded from AUTh to NGI developed nonlinear mechanical models combining springs, dashpots and sliders, for use in modeling SSI phenomena. X. Karatzia, seconded from the Uristol to HOCHTIEF developed calculation methods for the seismic analysis of interaction effects between buildings and underground lifeline structures (pipelines / channels) (slide 14.jpg).

WP4: The focus of this WP is the way in which earthquake ground motion varies along a gas pipeline in case of uniform and non-uniform soil profiles. N. Psyrras (seconded from UBristol to UToronto for 12 months) studied the above problem and published several journal and conference papers.

WP5: R. Baraschino was seconded from UNaples to VCE and evaluated the impact of modelling uncertainty on component- and system-level fragility considering record-to-record variability and epistemic variability (slide 21.jpg). G. Tsinidis (seconded for 12 months from USannio to VCE simulates numerically critical structural damages of gas pipelines when subjected to spatially variable ground seismic shaking (slide 25.jpg).

WP6: H. Thanopoulos, seconded from UPatras to VCE studied cost-effective monitoring technologies to detect damage in buried pipelines and new methods to identify post-quake soil failure through ultrasound detection (slide 27.jpg). To facilitate the above research, Dr. Zabel seconded from UWeimar (BUW) to VCE prepared a detailed state-of-the-art on the existing inspection methods (slide 28.jpg).

WP7: G. Baltzopoulos and P. Cito (slide 33.jpg) seconded from UNaples to VCE evaluated strong ground motion data in support of regional probabilistic seismic hazard analysis. Dr. De Luca and Dr. De Risi (slides 34-35.jpg) seconded from UBristol to Utoronto used machine learning techniques to quantify seismic hazard and applied the methodology for the case of a previous earthquake in Italy, research that was published in a quality ASCE journal (listed in the publications section).

Overall, research progressed as planned, while publicity, visibility and outreach were maximized through the international workshops in Bristol, Weimar/Frankfurt and Toronto (the latter being a non-contractual obligation). Proceedings of the above events are given in D9.1 and D9.2.
- The database of existing case studies and pipeline network properties in Europe (WP1, UBristol). Completion: 100%
- It is the first time that geographically distributed computing and Hybrid Testing concepts was employed for the purposes of soil-pipe interaction (WP2, UPatras & UToronto). Completion: 40%
- A more efficient Intensity Measures are identified for pipelines, enhancing the reliability of the probabilistic assessment of seismic damage (WP5, USannio). Completion: 30%
- It is the first time that asynchronous earthquake ground motion is performed in a rigorous way, involving different soil profiles and large scale computational modeling thus identifying unexpected damage modes (WP4, UBristol). Completion: 80%
- The novel formulation for low-order modeling of nonlinear response of pipelines for permitting computational efficient finite element modelling (WP3, UWeimar - BUW). Completion: 60%
- The study of the Impact of above ground buildings on soil-pipe interaction permitting the use of existing methods in densely populated urban regions (WP3, Hochtief). Completion: 50%
- A non-existing, comprehensive methodology and software for regional network assessment (WP7, UNaples) leading to a holistic methodology DESRAP Resilience Software to be used for other types of pipelines such as water and waste-water (WP7, UBristol & UNaples). Completion: 10%
Secondment of P. Cito from UNaples to VCE (WP6)
Secondment of X. Karatzia from UBristol to Hochtief (WP3)
Secondment of N. Psyrras from UBristol to UToronto (WP1)
Secondment of R. Barashino from UNaples to VCE (WP4)
Secondment of R. De Risi from UBristol to UToronto (WP6)
First soil-pipe experiment at UBristol (WP2)
Secondment of V. Zabel from UWeimar to VCE (WP5)
Secondment of C. Thanopoulos from UPatras to VCE(WP5)
Secondment of K. Tryfonos from UPatras to UToronto (WP2) - design of second experiment
Secondment of F. De Luca from UBristol to UToronto (WP6)
Secondment of C. Stutz from UKiel to VCE (WP3)
Secondment of G. Baltzopouulos from UNaples to UToronto (WP2) - prototype for mini hybrid testing
Secondment of G. Tsinidis from USannio to VCE (WP5)
Secondment of N. Psyrras from UBristol to UToronto (WP4)
Secondment of A. Markou from AUTh to NGI (WP3)