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Research in support to the implementation and validation of the Euro codes and the mitigation of the seismic risk in Europe

Objective

Specific Objectives

- To contribute to the development of rational assessment and re-design methods and retrofitting techniques for buildings and bridge piers, in particular, for fibre reinforced polymers (FRPs) strengthening: State-of-the-art and development of advanced methods and techniques applicable to structures in Europe (e.g. seismic retrofit of large bridge piers with square-hollow cross-section);
- To assess experimentally the performance of flat slab buildings and to identify/develop/ calibrate suitable numerical models to represent their behaviour under cyclic, earthquake-like loading;
- To better understand (experimental testing) and model (numerical analysis) the in-plane cyclic behaviour of plain/retrofitted masonry material/structures;
- To launch two specific test campaigns on: 1) isolation dissipation devices for seismic protection and 2) semi-active control of bridge structures under traffic loads (e.g. High-speed railway bridges);
- To consolidate the recent developments on continuous PSD testing with non-linear sub structuring.
Planned Deliverables

Specific deliverables to DGs:

- Deformation-based seismic assessment and re-design methods for reinforced concrete buildings;
- Design guidelines for retrofitting of existing bridge piers with rectangular-hollow cross-section using Carbon Fibre Reinforced Polymers (CFRPs).

As a result of the research:

- Report on innovative assessment and re-design methods for reinforced concrete structures;
- State-of-the-art report on strengthening techniques and design for bridge piers using FRPs;
- Report on the tests of a 3-storey flat-slab structure with experimental results, corresponding analysis and addressing modelling requirements and design implications;
- Masonry structures - Experimental activity: Construction of a new batch of shear walls with modified design to avoid boundary conditions problems in presence of retrofitting, and testing campaign on plain walls (different lateral loading histories), retrofitted walls (glass fibre reinforced concrete coating, FRC + resin coating) and plain/retrofitted medium size panels under biaxial homogeneous stress state (on a modified testing rig). Detailed technical notes including the main scientific achievements and the results of the numerical analyses and of the experimental tests;
- Masonry structures - Modelling activity: Improvement of the current joint model (introduction of cyclic degradation) and development/calibration of a new joint element for the interface coating/masonry so as to adequately simulate plain/retrofitted masonry structures under seismic loading. Numerical models, related software packages and user manual description;
- A semi-automatic field measurement method.

Summary of 2001 Deliverables: 31/12/2001

New materials and retrofitting techniques
The research work on the use of FRCs for strengthening and repair of RC structures concentrated on the analysis of the results from the tests on two buildings carried out at ELSA in 2000 (D2001-1, D2001-2) and on the study of possible reinforcement of bridge piers using advanced composite materials.
Furthermore, preparation of masonry wall-models reinforced with fibre concrete and externally reinforced with fibre-reinforced polymers was accomplished. The research did not yet get to a stage allowing for effective development of design guidelines. This objective will be hopefully achieved at the end of 2002.

Buildings, Bridges and Eurocodes
The research work relevant to Eurocode 8 concentrated on bridges. Specifically, a series of tests were carried out on large-scale models of existing bridge piers designed without appropriate seismic resisting characteristics.
Furthermore, the work on flat-slab structures was initiated addressing modelling issues and preparing the testing campaign on the 3-storey flat-slab building.

The following deliverables were achieved:
- Tests on four models of existing vulnerable bridge piers were carried out in order to assess their resisting capacity and to assess retrofitting solutions (D2001-3, D2001-4);
- PSD testing techniques with non-linear sub structuring were used to carry out the tests at ELSA (D2001-5);
- Analytical and Experimental assessment of flat-slab building structures started in 2001 having in view specific provisions still lacking in Eurocode 8. Further research work was carried out on the use of FRCs for strengthening and repair of RC structures (D2001-1).

Protection of Cultural Heritage
The testing campaign on masonry shear walls and medium-size panels has progressed slower than planned because of technical difficulties inherent to the testing rigs: two plain masonry shear walls have been tested under monotonic/cyclic lateral loading and two retrofitted masonry shear walls (metal fibre and glass fibre reinforced cement coating) have been tested under cyclic lateral loading (D2001-6). During these latter tests, a spurious sliding at the top of the wall has been observed, owing to the enhanced strength of the retrofitted masonry. The design of the wall/set-up has been modified in order to avoid this shortcoming in future tests. Moreover, the tests on medium size masonry panels uniformly loaded in one and two directions have been postponed until the implementation of a suitable software/hardware control (foreseen for the first half of 2002).

The modelling activity has progressed as planned. A new joint model able to reproduce the major features of the mortar joint behaviour has been implemented and calibrated on the basis of the shear wall test results. This model allows a good simulation of small-to-medium size masonry structures (because each individual brick need to be represented) but needs some improvement to take cyclic degradation into account. It constitutes the key element of the multi-level modelling approach implemented (D2001-7).

Two innovative retrofitting techniques have been investigated: metal fibre and glass fibre reinforced cement coating. At the light of the first two tests, the glass fibre reinforced concrete appears more promising but additional tests are required for optimising the characteristics of the coating (thickness, percentage of fibres).

The possibility of measuring the whole field of displacement on the masonry wall faces (using techniques developed in fluid mechanics and remote sensing) has been investigated. The preliminary results have been encouraging. If operational, such a technique could be extremely beneficial for the ELSA laboratory (more detailed experimental data and drastic reduction of the instrumentation, e.g. of a very time and money consuming phase of the experiments).

Results from work on masonry and monumental structures can be found elsewhere (D2001-8, D2001-9).

List of Publications in 2001

D2001-1: PINTO A., P. NEGRO, A. COLOMBO & H. VARUM. "The use of FRPs in seismic repair and retrofit: Experimental verification", Proceedings of the International Conference on Composites in Construction - CCC2001, October 10-12, 2001, FEUP - Porto, Portugal;

D2001-2: TSIONIS G., P. NEGRO, J. MOLINA & A. COLOMBO, "Pseudodynamic Tests on a 4-Storey Dual Frame Building", Report EUR 19902, 2001, Ispra (VA), Italy;

D2001-3: PINTO A., J. MOLINA & G. TSIONIS. "Cyclic test on a large-scale model of an existing short bridge pier (Warth Bridge - Pier A70)", Report EUR 19901 EN, EC, Joint Research Centre, ISIS, 2001;

D2001-4: PINTO A., J. MOLINA & G. TSIONIS. "Cyclic test on a large-scale model of an existing tall bridge pier (Warth Bridge - Pier A40)", Report EUR 19907 EN, EC, Joint Research Centre, ISIS, 2001;

D2001-5: PINTO A., P. PEGON, G. MAGONETTE, J. MOLINA, P. BUCHET & G. TSIONIS. "Pseudodynamic tests with non-linear substructuring and asynchronous motion of an existing RC bridge (Warth Bridge)", EUR EN, EC, Joint Research Centre, IPSC, 2001;

D2001-6: MOLINA J., Y. LE PAPE & P. PEGON. "Seismic Assessment of Masonry Structures - Experimental Program", Proceedings of the 3rd international Seminar on Historical Constructions - ISHC3, November 7-9, 2001, Guimarães, Portugal;

D2001-7: LE PAPE Y., A. ANTHOINE & P. PEGON. "Seismic Assessment of Masonry Structures - Multi Scale Numerical Modelling", Proceedings of the 3rd international Seminar on Historical Constructions - ISHC3, November 7-9, 2001, Guimarães, Portugal;

D2001-8: PINTO A., J. MOLINA, P. PEGON & V. RENDA. "Protection of the Cultural Heritage at the ELSA Laboratory", Proceedings of the 3rd international Seminar on Historical Constructions - ISHC3, November 7-9, 2001, Guimarães, Portugal;

D2001-9: DE LUCA A., E. MELE, J. MOLINA, G. VERZELETTI & A. PINTO. "Base isolation for retrofitting historic buildings: evaluation of seismic performance through experimental investigation", Earthquake Engineering & Structural Dynamics, Vol. 30, issue 7 (July 2001).

Output Indicators and Impact

- Results from the research carried out at ELSA on assessment and retrofit of structures are considered as reference tests which results constitute a solid basis for the development of Eurocode 8, part 1.4 presently under revision.
- The results from the tests on structures designed according new design methods have shown a few deficiencies and called the attention of code makers for a required longer period for maturing before their inclusion in Eurocode 8. Furthermore, the research on innovative assessment/re-design methods as well as on the new retrofitting techniques and performance criteria will contribute to bring Eurocode 8 into the new-generation set of design codes;
- The success of the experimental campaigns carried out at ELSA as well as the outstanding research achievements were key factors for a large number of successful SCAs (~20% of the total budget). It is believed that this success will also contribute, in the very near future, to set-up a network of excellence along the lines of the ERA;
- Development of advanced testing methods, namely the Continuous PSD testing method with non-linear sub structuring will consolidate the worldwide leading position of ELSA in PSD testing. Furthermore it will constitute a basis for the future initiatives (in FP6) on tele-participation and tele-operation.
Summary of the project

The project focuses on seismic risk reduction for populations through validation of design standards and contributes to developing protection techniques for civil and cultural heritage structures.
The effective assessment of these techniques is achieved through testing of the seismic behaviour of large-scale models of civil and historical buildings protected in different innovative ways (seismic isolation, passive energy dissipation and highly resistant strengthening materials). The research will be executed in close collaboration with other Organisations in the Member States, in particular those grouped since 1989 in EASML (European Association of Structural Mechanics Laboratories). The JRC reaction-wall facility of ELSA (European Laboratory for Structural Assessment) will be used for testing large-scale models of buildings, bridges and Cultural Heritage structures using the pseudo-dynamic test method in close collaboration with a European network including owners of shaking tables experts in dynamic structural behaviour.

Rationale

There is strong evidence from recent earthquakes that many existing buildings, bridges and cultural heritage constructions are unable to safely resist to severe earthquakes. Analytical and experimental studies are needed to assess the seismic vulnerability of these structures; to define/improve the guidelines both for design of new constructions and rehabilitation of existing ones. Similarly, research efforts are needed to develop structural repair, strengthening and retrofitting techniques for monuments and historical constructions, paying special attention to the application of new materials with good resistance, compatibility and durability, to innovative techniques allowing the reversibility of the protection intervention.
JRC will contribute to the development and validation of new methodologies, techniques and guidelines mainly performing pseudo-dynamic tests on large-scale mock-ups of structures at the ELSA Laboratory. Furthermore, the JRC will continue to improve the Pseudo-dynamic testing method in order to perform the most accurate experiments and to maintain its worldwide leading position in the field.

Call for proposal

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Coordinator

Institute for the Protection and Security of the Citizen
EU contribution
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Address

Ispra
Italy

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Total cost
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