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Experimental & Computational Hybrid Assessment Network for Ground-Motion Excited Soil-Structure Interaction Systems

Final Report Summary - EXCHANGE-SSI (Experimental & Computational Hybrid Assessment Network for Ground-Motion Excited Soil-Structure Interaction Systems)

The main objective of the EXCHANGE-SSI project is to establish the framework for an extended and continuous research staff exchange between E.U. institutions and the Mid-America Earthquake Centre Headquartered at the University of Illinois and other advanced North American centers in order to promote the transfer of knowhow on the application of distributed, hybrid or multi-platform experimentation for the study of seismic soil-structure interaction effects in bridges.

The overall work performed throughout the project and the results obtained are presented in the following section:

• Two Early Stage Researchers, were seconded from Aristotle University to the University of Illinois at Urbana Champaign (Hosting Institute) for 8 months according to the project schedule.

• One Early Stage Researcher was seconded from the University of Sannio, Italy to the University of Illinois at Urbana Champaign (Hosting Institute) for two months according to the project schedule.

• Two early stage Researchers were seconded from the Aristotle University to the University of Toronto for the period durations of 10 and 6 months respectively according to the project schedule.

• Two early stage Researchers were seconded from the University of Sannio to the University of Toronto for 11 (two different exchange visits of 5 and 6 month duration) and 2 months respectively according to the project schedule.

• Literature review on soil-structure interaction and hybrid experimentation in E.U. and U.S. for the seismic assessment of bridges was accomplished.

• Fundamental research work was accomplished on (a) the selection of earthquake ground motion scenario for the case of the bridge studied, (b) the effect of ground motion characteristics on the inelastic response of structures and (c) the derivation of the stiffness of the abutment-embankment system. The research outcome of this work has direct application on the hybrid experiment to be performed at the end of the project.

• An interactive software was developed for the selection of ground motions using sophisticated selection techniques. The software will be used for deriving the earthquake motions that will be used in the seismic assessment procedure of the bridge under study (available online at www.asextos.net/issars.html).

• A five span, seismically isolated, reinforced concrete bridge was established as a demonstration example for the multi-platform analysis and the Hybrid Experimentation.

• Geographically distributed, multi-platform simulation analysis was successfully performed for the case-study bridge between the Universities of Thessaloniki, Greece, Patras, Greece, Naples, Italy and Illinois at Urbana-Champaign, U.S.

• The preparation of the experimental setup of the University of Patras to be used for the final Hybrid Experiment has been accomplished and the equipment has been extensively tested.

• Trial communication between the experimental facility, the analysis coordination software and the (remotely located) numerical analysis platforms was successfully performed.

• A series of presentations and lectures was given by the Principal Investigators and the exchanged (seconded) personnel at the University of Illinois at Urbana-Champaign.

• Research work has been accomplished in the field of pseudo dynamic hybrid simulation of a hollow circular reinforced concrete bridge pier.

• Research work has been accomplished in the topic of the soil structure interaction effect through the Lumped parameter modeling method and an effective dynamically stable lumped parameter procedure has been developed in regard to the computational needs of the real time hybrid simulation method.

• Research work has been accomplished in the topic of spatial variability on structures taking into consideration the SSI effect. A potential extention to the field of natural gas pipelines was also examined.

• A distributed computing demonstration experiment was accomplished in March 2013.

•The first hybrid experiment of the project was conducted in October 2013 between the Universities of Patras and Thessaloniki according to the programme and consisted the first even experiment of this kind in Greece. It also served as a test bed for the major intercontinental test that followed.

• The final intercontinental hybrid experiment took place also in October 2013. The bridge studied was substructure into a bridge isolation component (i.e. bearing) that was physically tested at the University of Patras, the two abutments-embankment systems, the middle piers-soil-foundation systems and the bridges superstructure. It was the first experiment of its kind that successfully connected computer and laboratory equipment in both sides of the Atlantic and consists one of the major novelties that were resulted from this project. The outcome was successfully published and presented worldwide.

• The final workshop of the project, organized by the coordinator of the project (Dr. A. Sextos), took place at the Aristotle University of Thessaloniki in 11-13 November 2014.

All the above are described in the five deliverables submitted to the EC according to ANNEX I of the Grant Agreement and are published on the project website. It is essential to state that the project exceeded its initial scheduled expectations as the final outcome of a demonstration hybrid experiment was replaced by an actual full-featured Intercontinental hybrid experiment for the case of a real bridge.


The outcome of this project was:

(a) the knowledge gained from the long-established experience in the U.S. in terms of the geographically distributed hybrid experimentation and multi-platform simulation in order which enhanced the capabilities of the European laboratories and most importantly, permitted the successful design and execution of similar experiments in the European Research Area.
(b) the performance for the first time, of a hybrid experiment for bridge engineering purposes involving six partners from four different countries (Italy, Greece, U.S. France) and two continents (Americas and Europe).

Long-term and side impact of the project is also related to the:

• knowledge transfer between E.U. U.S. and Canada and a permanent research link among leading institutions in the numerical and experimental study of soil-structure interaction.
• the collaborative effect of the joint workshops and meetings that took place in E.U. U.S. and Canada that brought together the participating scientists and their institutions. This is further emphasised my the maximum visibility that the project received in the European scientific and professional community as well as through the breath of international and journal publications.
• the solid collaboration basis established through EXCHANGE-SSI for future joint research in the forthcoming Horizon 2020 framework. Notably, three other research proposals are currently under preparation while the network is being extended with more partners from Europe and North America. • the extrapolation of the knowledge gained by the study of the sub-structured soil-bridge interaction systems to other large scale problems in earthquake engineering research.