Final Report Summary - NIKER (New Integrated Knowledge Based Approaches to the Protection of Cultural Heritage from Earthquake-Induced Risk)
The project tackles the problem of earthquake-impact on cultural heritage (CH) assets starting from basic consideration that efficient protection, with substantial guarantee of compatibility and low-intrusiveness, can only be achieved on the basis of the 'optimised intervention' approach. This requires that the potentials of existing materials and components are as much as possible exploited in terms of strength and energy dissipation, and that candidate interventions are validated and optimised under specific, real life conditions.
At the project start, earthquake-induced failure mechanisms, construction types and materials, intervention and assessment techniques were cross-correlated with the aim of developing new integrated methodologies with a systemic approach. Traditional materials have been complemented and enhanced by innovative industrial processes (e.g. nano-limes or micro-silica for injection), and new high-performance (e.g. dissipative) elements have been developed. Novel collaborative combinations of them were tested on structural components (walls, pillars, floors, vaults) and on structural connections (wall-, floor- and roof-to-wall), through which the behaviour of single strengthened elements converges into the global structural response. The envisaged techniques have also been validated on model buildings and subassemblies. Advanced numerical studies allowed to parameterise the results and to derive simple and optimised design procedures. Early warning techniques for intelligent interventions and advanced monitoring techniques for knowledge based assessment and sequential implementation of interventions were also developed.
This bottom-up approach leaded to new integrated materials, technologies and tools for systemic improvement of seismic behaviour of cultural heritage assets. The new solutions have been compiled into guidelines for end-users. The participation of research centres, SMEs and Industry, public authority and end-users from different countries, including AC, ICPC and MPC, ensures an increased impact of the research.
Project context and objectives:
The main target of the project is the development of integrated and knowledge based methodologies for the protection of CH assets from earthquakes on the basis of optimisation and 'optimised intervention' approach. This general objective can be achieved by overcoming the shortcomings of the current approaches, which are mainly related to the use of inadequate materials; the use of inadequate intervention techniques, and the use of inadequate tools for analysis and/or analysis, which are also carried out on the basis of limited information and/or obsolete or inadequate design methods.
Hence, the main objectives of the project are:
- creating a database with new relational structure, with the task of orienting and assisting the development of advanced materials and innovative techniques;
- experimental testing, numerical simulation and derivation of design methods for vertical and horizontal structural elements, for connections and for the overall seismic behaviour of buildings;
- development of knowledge-based assessment procedures and final validation of the entire methodology on real case-studies, with the finalisation of guidelines for end-users.
These general objectives have been accomplished by achieving specific detailed objectives along the course of the project, concerning both scientific-technological aspects and dissemination aspects. A synthesis list of these project objectives is presented hereafter:
a) creation of a new structured database that links earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques;
b) development of advanced materials and improved techniques for intervention on structural elements (vertical and horizontal elements);
c) experimental validation of the envisaged technological solutions for vertical structural elements with special developed testing procedures; numerical parametrical assessment; development of rules for optimised design;
d) experimental validation of the envisaged technological solutions for horizontal structural elements with special purpose developed testing procedures; numerical parametrical assessment; definition of optimised design procedures;
e) development of innovative intervention techniques for structural connections, in particular of strengthening elements able to dissipate seismic energy;
f) experimental quantitative characterisation of the behaviour of connections before and after strengthening, by developing new specific testing strategies;
g) development of shaking table test set-ups and testing strategies for sub-assemblies; experimental characterisation of their seismic behaviour before and after strengthening;
h) integration, validation and assessment of intervention techniques by experimental evaluation of overall seismic response of model buildings on shaking table;
i) derivation, from the previous three points, of reliable models for connections and substructures; parametric assessment; sensitivity study of buildings; definition of optimised performance based design procedures;
j) calibration of innovative measuring devices or systems, including embedded instruments in dissipative devices, on laboratory specimens and subsequent onsite application;
k) development of integrated methodologies that include i) monitoring; ii) structural modelling; iii) selection, design, and application of minimised interventions; iv) evaluation of execution of intervention; v) step-by-step procedure in the application of interventions;
l) implementation of the project results into guidelines and subsequent transfer into codes of practice and standards;
m) dissemination and exploitation of the results, quantification of the impact of the project on stakeholders, end-users, and public bodies charged with cultural heritage buildings maintenance and management.
Project results:
The exploitable results from the NIKER project can be roughly grouped into two main categories. The first category is constituted by the exploitable knowledge, meaning knowledge that has a potential for industrial or commercial application in research activities, or for developing new products or processes or services. The second category comprises the exploitable products and measures, which already constitute final objects, products or instructions that can be used by the end-users.
Taking into account the structure of the project and its final aim, related to the development of integrated methodologies to ensure the efficient protection with 'minimum intervention' of cultural heritage assets, with respect to the impact of earthquakes, the project results can be grouped as follows:
Exploitable knowledge
1. Creation of a new structured database that links earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques
The catalogue has been structured in an interactive, web-based form and is available online at http://niker.isqweb.it/ and will be soon directly linked from the main page of the project website http://www.niker.eu/ it has been developed by merging information deriving from literature survey and tests carried out during the project, and concerning:
- inventory of earthquake induced failure mechanisms related to construction types, structural elements and materials;
- critical review of retrofitting and reinforcement techniques related to possible failure mechanisms, requirements, performance parameters;
- critical review of methodologies and tools for assessment of failure mechanisms and interventions.
2. Experimental validation of the envisaged technological solutions for vertical and horizontal structural elements
The following structural elements and systems have been tested in original conditions, and the following materials / techniques for interventions have been developed and experimentally characterised, so as to find constitutive laws and develop design procedures for the strengthened elements:
- strengthening of multi-leaf stone masonry walls by means of hydraulic lime grouts and leaf-tying;
- strengthening of rammed earth, earth block and cob masonry walls by means of vertical textile belts;
- strengthening of adobe brick masonry walls by means of steel wire ropes mechanically fastened to the wall and disposed according to an X shape, geo-net PET or geo-nets PP;
- strengthening of dry brick walls by means of geo-nets PET and mortar;
- strengthening of solid brick masonry walls by means of steel wire ropes mechanically fastened to the wall and disposed according to an X shape;
- strengthening of wooden floors by means of double planking, panel consisting of long mineralised wood-wool bound, OSB panel, diagonal steel, wooden diagonal, composite diagonal and wooden of composite diagonal net;
- strengthening of arches and vaults by means of composite materials made with various types of fibers (steel, basalt, carbon) and mainly inorganic matrixes made of hydraulic lime mortar or epoxy matrixes.
In addition, compatibility, durability and effectiveness tests have been carried out on:
- the behaviour of solid clay bricks covered by a layer of externally applied FRP textiles, in case of forces normal to the reinforcements surface, based on performing pull-off tests;
- the behaviour of such reinforcements, in case of parallel forces reproducing their usual working conditions (fibres axially loaded and interface tangentially stressed); those tests are supposed to provide all the information required to characterise the local bond behaviour;
- the effect of humidity and of thermal cycles on the delamination of the FRP strips from the masonry support;
- the injectability of grout admixtures on stone masonry walls and the microstructural properties of the grout to original masonry material interface;
- the durability of natural hydraulic lime mortars.
3. Experimental quantitative characterisation of the behaviour of connections before and after strengthening
The following systems have been tested in original conditions, and the following techniques for interventions have been developed and experimentally characterised, so as to find constitutive laws and develop design procedures for the strengthened elements:
- strengthening of timber roof connections by means of dovetail halved joints;
- strengthening of wall-to-timber floor connections by means of timber lancing or grouted metallic anchors with hinged ends;
- strengthening of wall-to-wall connections by means of FRP / metallic bonded anchors, metallic ties with ductile anchorage system, grouted metallic anchors, grouted metallic anchors with hysteretic dissipative device and grouted metallic anchors with frictional dissipative device.
4. Development of test setups and testing strategies for sub-assemblies and experimental characterisation of the seismic behaviour of original substructures and substructures strengthened with integrated interventions by shaking table tests
The following structural elements and systems have been tested in original conditions and the following materials / techniques for interventions have been developed and experimentally characterised, so as to develop simultaneously the testing procedures and to find constitutive laws and develop design procedures:
- strengthening of multi-leaf stone masonry walls by means of hydraulic lime grouts and leaf-tying and of adobe walls and columns;
- strengthening of scaled earth block masonry buildings by means of different in-plane stiffness roof;
- strengthening of scaled subassemblies consisting of three piers made of three-leaf stone masonry, connected with a timber floor at their top by means of hydraulic lime grouts on the walls and different in-plane stiffness floors;
- strengthening of scaled subassemblies consisting of two piers made of hree-leaf stone masonry, connected with brick arches and cross vault.
5. Integration, validation and assessment of intervention techniques by experimental evaluation of overall seismic response of model buildings on shaking table
The model buildings have been tested in original conditions and after strengthening with hydraulic lime grouts on the multi-leaf stone masonry walls and enhancement of diaphragm action of floors.
6. Derivation, from the previous three points, of reliable models for connections and substructures; sensitivity study of buildings to quantify building seismic performance and response parameters to be used in seismic assessment and design; definition of optimised performance based design procedures related to overall building performance
In particular, it has been:
- derived design methods for vertical and horizontal structural elements and connections and for the overall seismic behaviour of buildings. Different typologies ranging from traditional houses to churches, representative of the cultural heritage asset, were considered and analysed;
- derived, from experimental tests and detailed numerical models, simplified and more complex models for in and out-of-plane behaviour of vertical elements, in-plane behaviour of floors, and longitudinal and transversal response of vaults to be implemented in global analyses;
- developed reliable numerical models of connections and substructures, made parametric assessment aimed at identifying interactions with repaired vertical and horizontal elements, defining optimised design procedures, carrying out sensitivity analyses based on the calibrated models. These analyses allowed studying the interactions of various conditions, as the state of the structural elements, state of the connections and boundary conditions;
- derived, from these analyses, simplified and more complex models of connections and substructures to be implemented in global analyses;
- integrated the above mentioned models and carry out sensitivity study of buildings according to geometry, intervention techniques, stiffness of horizontal elements and connections;
- quantified building seismic performance and response parameters to be used in seismic assessment and design.
7. Development of integrated methodologies that include:
i) monitoring as knowledge-based assessment and early warning tool;
ii) creation and update of reliable structural models;
iii) selection, design, and application of minimised interventions;
iv) evaluation of execution of intervention;
v) step-by-step procedure in the application of interventions.
The methodologies have been validated through application to 20 real case studies, selected to cover a wide and representative range of conditions regarding geographical location (different countries) local seismicity (low, medium, high), construction material (stone and brick masonry, earth), structural typologies and uses (towers and minarets, churches, large cathedrals, palaces), preservation condition (different levels of damage) and risks involved (i.e. people at risk, valuable artistic contents at risk).
This result was attained through several tasks involving:
- calibration of monitoring systems and devices;
- development of automatic systems for monitoring data-processing;
- development of targeted monitoring strategies and application of monitoring systems and devices for the identification of the real behaviour of buildings;
- application of the knowledge obtained through monitoring to the creation and updating of reliable structural models, to the definition of minimal interventions and to the evaluation of interventions;
- based on the previous evaluation, the optimal intervention techniques to selected case studies have been implemented, including the application of instrumented dissipative devices;
- conclusions on the effectiveness of the interventions and the corresponding optimal quality assessment procedures have been drawn.
Exploitable products:
1. Development of advanced materials and improved techniques for intervention on vertical and horizontal structural elements. Besides all the above mentioned technique, a direct industrial product development concerned the elaboration of grout mixtures with 10 % replacement of hydraulic lime with an ultrafine amorphous aluminosilicate, naturally occurred mineral of volcanic origin, processed in powderous form and more specifically 99,9 % of the mass of such processed aluminosilicate is below 45 µm.
2. Development of innovative intervention techniques for connections and of strengthening elements able to dissipate seismic energy
In particular, the new devices are:
- dissipative prototypes conceived as add-on for enhancing the performance of stainless steel ties. Hysteretic properties of a stainless steel element, shaped to optimise its post-elastic behaviour, or a friction mechanism set to be triggered for a certain level of pulling / pushing force, the dissipative devices allow small relative displacements, dissipating energy and hence reducing the impact of seismic force on the walls, and controlling damage;
- connection devices, which improves the connections between the structure of the floors and the resistant walls and can increase the safety of floors, and the global stability of the buildings, through the contribution of wooden floors to the bracing of the walls;
- connection between vertical structural elements, allowing them to stop working separately, as they start having a conjunct behaviour, made effective by installed rod. It Increases the deformation capacity and energy absorption of the structure, in case of horizontal loads (seismic), through the ductility that characterises the anchor plates. It can also be used as an element for preventing separation of structural elements (usually orthogonal).
3. Calibration of innovative measuring devices or systems, including embedded instruments in dissipative devices, on laboratory specimens and subsequent on-site application on real case studies
In particular, the newly developed product is a monitoring system consisting of a grouted stainless steel anchor coupled with a set of sensors and a data acquisition system. The system is conceived to be installed in a structure with the double function of repairing / strengthening and monitoring the response of both building and anchor. The sensors are designed to record a set of relative movements - vertical and horizontal, out-of-plane and in-plane - between the connected that are typical of common damage mechanisms - e.g. out-of-plane overturning.
4. Implementation of the project results into guidelines for an integrated applicability of the proposed methodologies and subsequent transfer into codes of practice and standards
The following documents have been produced and made available to the public:
- guidelines for design and execution of optimum interventions for end users;
- guidelines for assessment and improvement of connections and buildings for end-users;
- design and application guidelines for stick-slip and hysteretic dissipative anchors with embedded sensors;
- guidelines for reliable seismic analysis and knowledge based assessment of buildings;
- integrated methodology for effective protection and earthquake improvement of cultural heritage.
Potential impact:
The global objective of the project is to promote new sustainable and preventive strategies, concepts, integrated methodologies and techniques for protection of CH assets from earthquakes. The achievement of this main objective ensures to improve safety and, more in general, the quality of life of citizens and to improve the attractiveness of Europe, particularly its cities, buildings, and monuments.
All the techniques and materials that have been tested and validated within NIKER, have been also numerically reproduced and implemented into sophisticated models, that allowed gathering deeper knowledge on the behaviour of original and strengthened elements and of entire buildings. At the same time, modelling and analysis strategies and design methods for better interpreting the structural response and optimising the design process have been developed. The impact of these results to the efficient protection and preservation of CH is direct and transparent.
In addition, as earthquakes constitute the natural hazard that yearly causes the highest number of casualties in the world, it is clear that the practical application of the project results may turn in an increased safety, hence quality of life, for the society. So far, there has been an intense dissemination activity (carried out in regions recently hit by earthquakes, but not only), at a general public level, that allowed raising awareness to achieve rapidly the above-mentioned objectives. At the same time, intense dissemination of results at a stakeholder level (Ministry of Cultural Heritage, etc.), that has been carried out during the project and is being still carried out, allow planning of mitigation strategies that will have a strong impact on safety, quality of life, protection of CH and increase of related activities. As a demonstration, the Ministry of Cultural Heritage of Israel (IAA) is now starting working on a seismic risk plans on the basis of the NIKER outcomes, whereas the Ministry of Cultural Heritage in Italy (MiBAC) is resorting to the documentation produced within the NIKER project for making professional refresher courses for engineers and architects working on CH assets.
Another aspect of the developed technologies is that they are reliable, cost-efficient and knowledge-based. On one hand, the increased safety allows for a sustainable growth, as societies that are constantly coping with the consequences of natural disasters do not achieve sustained growth. On the other hand, the main approach of the project 'minimisation of interventions', by means of intense knowledge of the structure, allow reducing the use of resources and the impact on the environment, thus improving sustainability. As an example, the monitoring strategies developed and implemented allow, in certain cases, avoiding the execution of unnecessary interventions, thus implementing in practice the conservation principles. This has been demonstrated, e.g. in the case of the Arena of Verona, which has been monitored also during seismic shakings, on the basis of which records, the real state of damage and the updating of predictive numerical models has been done. The characterisation of techniques in terms of compatibility and long-term behaviour also has a primary role on sustainability, as this means making durable interventions on CH assets, which do not affect the environment, and which instead consume a minimum of resources. At the same time, this approach is based on technologies for knowledge, assessment, and design of new materials that favourably affect industrial competitiveness.
As regards the latter point, the technologies and methodologies developed within the project are cost-effective, optimised, assessed by real case studies and ready to be disseminated and exploited by means of application guidelines. Hence, by means of the NIKER project, the European construction industry, together with other service related SMEs, will achieve greater competitiveness, with a positive outcome on employment and the use / development of skills. The construction sector in particular, during the years of NIKER, has faced the worst crisis since the beginning of the modern era. It has been demonstrated that the further development of the Sector is limited by several shortcomings, particularly concerning the production of new structures. Hence, construction activities devoted to adaptive re-use, repair and maintenance are becoming a pillar of the sector.
This is also demonstrated by the lively presence, in the NIKER partnership, of four companies of the sector, plus two engineering firms. During the period, they have all expanded, or consolidated, the CH building related activities, with a clear countertrend with respect to the current economic overview. In most of the cases, the companies have been able to develop new materials and products within the project, and the service companies to increase their market share in reconstruction / restoration sector. In addition, all technologies covered within, mainly, WP9 (inspection and monitoring of buildings), will also have a direct contribution to European employment, as to meet these demands, structural assessment operators and service providers will have to employ more specialised staff.
Lastly, conservation of the existing CH is of vital importance for the maintenance and improvement of the tourism sector in Europe. Setting twenty different and very interesting case-studies in different countries has already had a media impact, with involvement and support of local authorities to the NIKER, which entailed direct involvement in the project of institutions that are also active in tourism promotion.
The active participation of countries beyond Europe allowed taking into account specificity of various CH assets and environmental conditions, ensuring transferability of results beyond the EU. Various tested systems and materials (e.g. timber framed walls, or earthen materials, etc.) are typically found in other countries. The collaboration of institutions coming from different countries on, and through, real case-studies, located in different places, has been of strong importance to set up relations and improve neighbouring countries and regional policies. The very active dissemination carried out at a national level by the project partners coming from ACs, ICPCs and MPCs has definitely helped in this sense. In addition, the project required a trans-national approach because it aims to solve problems common to most of Europe. Active cooperation of partners of different European countries on portions of the NIKER research activities has actually achieved the goal of increasing trans-national technological cooperation amongst Industry, SMEs, national and regional associations, and RTD-performers, that will profitably continue well beyond the NIKER project closure.
The project will also contribute to European standardisation and regulation. Research results can be included on one hand into the codes of practice of the managing authorities, and this is being already done through the public body participating in the NIKER partnership (IAA), but also with the many institutions involved during the project duration. On the other hand, research results can be included into the European codes, and this is also being already pursued, as demonstrated by the active participation of many partners in standardisation bodies (CEN TC 346 Conservation of Cultural Property; the various mirror group in the European countries as UNI - NORMAL in Italy, the international ISO TC98 SC2 WG6 - Heritage Structures, etc.), and in pre-normative technical committee (e.g. RILEM, where, as an example, the information derived on composite material application on masonry is being already introduced in TC 223-MSC 'Masonry Strengthening with Composite materials', where various NIKER partners are active).
The target group for the NIKER outputs are the end users, namely:
(a) those who manage the cultural heritage (public entities, bodies responsible of building maintenance, authorities, decision-makers);
(b) those who have the responsibility of choosing and designing the interventions on cultural heritage assets (designers, architects, engineers, consultancy firms);
(c) those who produce and apply the materials and technologies (mainly SMEs, Industry and construction companies);
(d) those who can further develop, study and propose the envisaged technologies (students and researchers).
On the other hand, the results arising from research are to be disseminated among the target groups listed above by means of:
(a) presentations at technical conferences and publication of papers;
(b) publication in technical and peer reviewed journals;
(c) promotion of training courses directed to professionals and contractors;
(d) presentation at commercial events and in specialist fairs;
(e) promotion of training and continuing education courses directed to professionals and technical and management staff of entities responsible of cultural heritage maintenance;
(f) presentation of the results at university academic courses, technical universities and teaching centres.
The first dissemination activities took place a couple of months before the beginning of the project: a specific web site with project information and potential access to project results (see http://www.niker.eu online) was made available in February 2010 (PM2) by the project coordinator, UNIPD.
An overall number of 316 dissemination actions have been carried out, which represents, on average, more than 8 monthly activities and around 6 dissemination activities per partner per year. These figures represent a deep commitment of the consortium in promoting and disseminating the research outputs.
The participation on conferences and meetings represents 46 % of the events, followed by the offer of training and academic courses, workshops and seminars, and academic thesis. It is especially worth to highlight that two common Special Sessions were organised together with the PERPETUATE project, aiming at presenting the most recent developments within both projects in an integrated way. These two special sessions were organised in the framework of two important international conferences in the field of earthquake engineering and cultural heritage conservation: the 15th World Conference in Earthquake Engineering (15th WCEE), 24 to 28 September, 2012 Lisbon, Portugal and the 8th International Conference on Structural Analysis of Historical Constructions (SAHC 2012), 15 to 17 October 2012, Wroclaw, Poland.
The dissemination level, according to the type of target group and to the type of action carried out, can be regional, national or international. From the 316 dissemination activities, an average of 50 % of the actions was carried out at national level in the countries involved in the project. It is worth to note that 19 % of the actions had a regional emphasis, as the creation of a network of capillary dissemination at local level (i.e. direct contact with end users) is very important for the success of the tools under development. A relatively good balance has been reached so far between national / international actions as well as between regional / national ones. 19 % of the dissemination actions have been carried out outside the countries of the consortium. Partners did an important effort to create impact at international level, but focused in their countries, so the results can effectively be transferred to end-users. It is also hoped that this effort will allow the development of new cooperative projects inside Europe and the Mediterranean basin, as a continuation of the NIKER project.
The target groups of the dissemination activities were mainly constituted by scientists and researchers (37 %), followed by architects, engineers and professional bodies (27 %), and university and training organisations (25 %). Architects, engineers and professional bodies are also important secondary target groups, together with scientists and researchers, university and training organisations and general public. This scenario shows that the NIKER outputs are welcome both by the scientific community and professionals. Furthermore, MSc and PhD students (as future highly qualified professionals) are also benefiting from the project results.
The results of the project (in terms of both knowledge and products) will be exploitable by all the partners involved in the consortium, each one in accordance with its own field of activity.
The new structured database developed under WP3 enables to link earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques. In a more detailed way, the database allows:
(a) generating new cross-correlations between key factors as ductility and energy dissipation capacity, allowing using the most recent state-of-the-art knowledge;
(b) fixing design parameters and requirements, for interactive development of materials and techniques;
(c) defining the performance levels needed for advanced design of interventions.
These results constitute a powerful exploitable knowledge, as no database of this kind has been elaborated before. The database has been loaded with basis on results from peer-reviewed published literature.
As most of the experimental testing procedures adopted within the NIKER project are not yet standardised, the results obtained can be used for the improvement of laboratory testing setups and procedures, for fixing pre-normative recommendations in the field. Therefore, these testing setups and procedures constitute a relevant exploitable knowledge as they will be used in near future as standard procedures by the scientific community. A good example is the publication of a journal paper about the execution of bond tests on brick masonry specimens strengthened with composite materials.
The numerical modelling gives as a result the definition of suitable modelling strategies for the historical masonry structures of different material and geometric complexity and an assessed way for defining the key mechanical parameters. The novelty of the numerical approach followed stands also in the complementary use of different modelling approaches and in the simultaneous definition of modelling procedures for different types of masonry structures, which provides a considerable broad view of the problem.
The developed guidelines characterise the design and execution of innovative intervention technologies on vertical and horizontal elements. The various techniques described in the documents present details on materials, design rules and relation with possible failure mechanisms and damages. The guidelines suggest also optimum intervention for improvement of seismic performance of vertical and horizontal elements.
The multidisciplinary nature of interventions on cultural heritage presents a high complexity for professionals to achieve the necessary knowledge to support making decisions. In this sense, the procedure required to support and control an adequate decision making process, aimed at the selection of correct interventions, is also addressed in the guidelines.
Throughout the project, also innovative products and techniques have been developed and they do represent a step forward, in the sense that can be looked at as an incorporation of scientific knowledge. Thus, they represent also an important competitive, technical and economic added-value for the companies involved in civil and seismic engineering and CH protection. In this sense, companies will be able to sell an all-inclusive package, providing both the products and the design of the required intervention.
Bozza Legnami was mainly involved in the reinforcement of wooden floors, proposing and comparing several solutions of in-plane structural strengthening. The added value of the research lies in the given first classification of in-plane strengthening, which led to the elaboration of a quantitative positioning of the rigidity of the proposed intervention. The key features of this kind of intervention are the possibility of a dry strengthening solution, the lightness of the reinforcement and the high adaptability to existing or new buildings, against a cost which is in line with the one of similar interventions already in use. The reversibility of the intervention is of main importance as it concerns cultural heritage, since it is a core principle required by the government authority. The company will further develop this research in order to outline a simplified methodology for the identification of the correct intervention techniques to be used according to the conservation status and to the dynamic response of the existent masonry buildings with wooden floors. It is envisaged that the results of this research would be implemented into computing software for the use of sector professionals.
The prototype for the dissipative anchoring device and the innovative monitoring anchoring device would benefit Cintec's competitiveness, whose 40 % of the turnover is in the heritage building market.
The dissipative prototypes are conceived as add-on for enhancing the performance of stainless steel ties. Cross-ties are indeed able to provide a connection at the joints of perpendicular sets of walls, where poor quality, previous damage or general wear and tear may facilitate crack onset and eventually out-of-plane failure. Thus, they meet the requirement of restoring the box-like behaviour of masonry structures, allowing for the redistribution of horizontal load in sets of perpendicular walls without substantially increasing the mass. Nonetheless, anchors can also cause pull-out damage at the head of the anchorage and increase in-plane diagonal cracking because of the different deformability of steel and masonry. This might become a major problem when damage limitation should be pursued, avoiding cracking in precious plasters, frescoes, and other culturally valuable finishes. Thanks to either the hysteretic properties of a stainless steel element, shaped to optimise its post-elastic behaviour, or a friction mechanism set to be triggered for a certain level of pulling/pushing force, the dissipative devices allow small relative displacements, dissipating energy and hence reducing the impact of seismic force on the walls, and controlling damage.
On the other hand, the monitoring system consists of a grouted stainless steel anchor coupled with a set of sensors and a data acquisition system. It relies on CINTEC's technology and is conceived to be installed in a structure with the double function of repairing / strengthening and monitoring the response of both building and anchor. The purpose is to have a continuous monitoring of the system over either a short period immediately after a major earthquake and before the design of the permanent repairs, or in the long term as control of the performance of the strengthen structure and as an early warning system for future strong motion occurrences. Recorded data can be correlated to determine the evolution of damage to the portion of structure where the anchor is installed as consequence of micro- tremors, relative settlements in the ground, and so on. Whereas a standard monitoring system detects the response of a structure at a global level, the instrumented anchor can capture localised phenomena. The system is designed and assembled in house so that installation of a number of separate sensors is avoided, reducing the amount of resources needed and the risks for contractors working on site. The sensors are designed to record a set of relative movements (vertical and horizontal, out-of-plane and in-plane) between the connected that are typical of common damage mechanisms. On the basis of the recorded data, preliminary conclusions can be drawn on whether the temporary strengthening is sufficient to ensure a certain seismic response of the structure or whether other interventions are required. Once the system is fully calibrated, software for the analysis of the recorded data and the comparison with a set of limit values is developed, so that in the case of urgent interventions, when data are required in a short time, the whole process of monitoring is simplified.
S&B developed µ-SILICA, an ultrafine amorphous aluminosilicate, naturally occurred mineral of volcanic origin, processed in powderous form. It has many innovative features such as: low water demand, low content in water soluble alkalis, natural pozzolan-compatibility with the initial building materials, off white colour, easy to use in mortars and generally restoration works, it lowers permeability on chloride, low CO2 footprint. Grout mixtures using µ-SILICA proved to have increased long term strengths, better resistance to salt crystallisation, lower shrinkage, more sustainable design mix. Following the development of the aforementioned innovative solution within the NIKER project, the company estimates to increase its market share in the restoration industry (where now S&B's position is almost negligible), increasing its own turnover and export, as well as strengthening its brand.
Monumenta developed some connection devices with high potential of application on site and relevant contribute in the scope of global reinforcement solution for ancient buildings. These devices are also highly compatible with the original construction design of old buildings (low-intrusiveness), are lighter and easier to apply (when compared with other solutions) and therefore the interventions based on these devices should be faster and cheaper than it generally is. The use of these devices, combined or not, allows to achieve satisfactory results regarding the structural behaviour of existing ancient buildings using an alternative approach to the reinforcement solutions that are nowadays commonly in use.
This new approach should be enhanced and presented to the main job promoters and designers, as aspects like economy of resources (human, natural, time, energy, etc.) and the respect of the identity of those buildings (because of its low-intrusiveness) are very important for the acceptance of this alternative methodology. Intensive and efficient marketing activities must be carried out in order to show (from the financial, sustainability and social points of view) that the use of these devices, once combined, can replace, in some scenarios, the use of other 'heavier' techniques / solutions.
Besides the developed guidelines and products, another important impact of the NIKER project is associated to the decision making and educational processes within bodies appointed for cultural heritage management and maintenance. Their direct or indirect involvement in the project raises awareness about the need for knowledge-based scientific approaches and methodologies in the protection of cultural heritage and use of seismic risk mapping. The case of IAA is a very good example about the setting of governmental priorities and policies in the area of cultural heritage.
The knowledge achieved within the project, through the case-studies in Bosnia-Herzegovina, improved the understanding of the seismic behaviour of stone masonry traditional minarets, raising the level of competitiveness and the scope of future research and commercial activities for IPM.
ZRS can take advantage of an analogue worked out knowledge for earthen materials (mechanical properties, methods for strengthening with assessment of effects and limits of use) achieved through the case study on the Preceptory in Ambel, Spain. The developed knowledge obtained within the scope of NIKER was already used in projects, realised by or in corporation with ZRS. The improved knowledge about earthquake induced risks and possible protection measures, not only for earthen buildings in particular but also in general, is a competitive advantage and has led to project requests among others in Iraq and Colombia.
Finally, the different dissemination activities carried out at different levels, such as the publication of academic theses, the participation in conferences and exhibitions, the organisation of workshops, the publication of technical and scientific papers, etc., constitute both an exploitable knowledge and product of the research. These actions can be seen as foundations on which further research carried out especially by RTDs will be based on. Publications and communications inside the scientific community are a very powerful way to enrich the project results with other people experience and to make the scientific community aware of the project results to help them identifying future research needs.
Project website: http://www.niker.eu
UNIPD:
Prof. Claudio Modena
claudio.modena@unipd.it
Tel/fax: +39 049 827 5613
BAM:
Dr Patrick Fontana
patrick.fontana@bam.de
Tel: +49-308-1041712
ITAM:
Prof. Milo Drdácký
drdacky@itam.cas.cz
Tel: +42-028-3880854
NTUA:
Prof. Elizabeth Vintzileou
elvintz@central.ntua.gr
Tel: +30-210-7721272
POLIMI:
Dr Antonella Saisi
saisi@stru.polimi.it
Tel: +39-022-3994386
UMINHO:
Prof. Paulo Lourenço
pbl@civil.uminho.pt
Tel: +35-125-3510209
UPC:
Prof. Pere Roca
pere.roca.fabregat@upc.edu
Tel: +34-934-017381
UBATH:
Prof. Dina D'Ayala
d.d'ayala@ucl.ac.uk
GUNI:
Prof. Ali Ihsan Unay
unay@metu.edu.tr
Tel: +90-312-5823658
ENA:
Prof. Khalid El Harrouni
kelharrouni@gmail.com
Tel: +21-266-1374150
CDCU:
Prof. Mona Fouad Alì
monalyeg@yahoo.com
Tel: +20-237-349449
IAA:
Mr Jacques Neguer
jacque@israntique.org.il
Tel: + 97-235-042275
BOZZA:
Mr Enzo Bozza
info@bozzalegnami.it
Tel: +39-049-629699
CINTEC:
Mr Dennis Lee
dennislee@cintec.co.uk
Tel: +44-163-3246614
IMP:
Mr Mustafa Humo
mhumo@interprojekt.ba
Tel: +38-736-555132
S&B:
Mr Thanasis Karalis
T.Karalis@sandb.com
Tel: +30-210-6296177
ZRS:
Dr Christof Ziegert
ziegert@zrs-berlin.de
Tel: +49-303-98009531
MONU:
Mr Vítor Cóias
vitorcoias@gestip.pt
Tel: +35-121-3712580
At the project start, earthquake-induced failure mechanisms, construction types and materials, intervention and assessment techniques were cross-correlated with the aim of developing new integrated methodologies with a systemic approach. Traditional materials have been complemented and enhanced by innovative industrial processes (e.g. nano-limes or micro-silica for injection), and new high-performance (e.g. dissipative) elements have been developed. Novel collaborative combinations of them were tested on structural components (walls, pillars, floors, vaults) and on structural connections (wall-, floor- and roof-to-wall), through which the behaviour of single strengthened elements converges into the global structural response. The envisaged techniques have also been validated on model buildings and subassemblies. Advanced numerical studies allowed to parameterise the results and to derive simple and optimised design procedures. Early warning techniques for intelligent interventions and advanced monitoring techniques for knowledge based assessment and sequential implementation of interventions were also developed.
This bottom-up approach leaded to new integrated materials, technologies and tools for systemic improvement of seismic behaviour of cultural heritage assets. The new solutions have been compiled into guidelines for end-users. The participation of research centres, SMEs and Industry, public authority and end-users from different countries, including AC, ICPC and MPC, ensures an increased impact of the research.
Project context and objectives:
The main target of the project is the development of integrated and knowledge based methodologies for the protection of CH assets from earthquakes on the basis of optimisation and 'optimised intervention' approach. This general objective can be achieved by overcoming the shortcomings of the current approaches, which are mainly related to the use of inadequate materials; the use of inadequate intervention techniques, and the use of inadequate tools for analysis and/or analysis, which are also carried out on the basis of limited information and/or obsolete or inadequate design methods.
Hence, the main objectives of the project are:
- creating a database with new relational structure, with the task of orienting and assisting the development of advanced materials and innovative techniques;
- experimental testing, numerical simulation and derivation of design methods for vertical and horizontal structural elements, for connections and for the overall seismic behaviour of buildings;
- development of knowledge-based assessment procedures and final validation of the entire methodology on real case-studies, with the finalisation of guidelines for end-users.
These general objectives have been accomplished by achieving specific detailed objectives along the course of the project, concerning both scientific-technological aspects and dissemination aspects. A synthesis list of these project objectives is presented hereafter:
a) creation of a new structured database that links earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques;
b) development of advanced materials and improved techniques for intervention on structural elements (vertical and horizontal elements);
c) experimental validation of the envisaged technological solutions for vertical structural elements with special developed testing procedures; numerical parametrical assessment; development of rules for optimised design;
d) experimental validation of the envisaged technological solutions for horizontal structural elements with special purpose developed testing procedures; numerical parametrical assessment; definition of optimised design procedures;
e) development of innovative intervention techniques for structural connections, in particular of strengthening elements able to dissipate seismic energy;
f) experimental quantitative characterisation of the behaviour of connections before and after strengthening, by developing new specific testing strategies;
g) development of shaking table test set-ups and testing strategies for sub-assemblies; experimental characterisation of their seismic behaviour before and after strengthening;
h) integration, validation and assessment of intervention techniques by experimental evaluation of overall seismic response of model buildings on shaking table;
i) derivation, from the previous three points, of reliable models for connections and substructures; parametric assessment; sensitivity study of buildings; definition of optimised performance based design procedures;
j) calibration of innovative measuring devices or systems, including embedded instruments in dissipative devices, on laboratory specimens and subsequent onsite application;
k) development of integrated methodologies that include i) monitoring; ii) structural modelling; iii) selection, design, and application of minimised interventions; iv) evaluation of execution of intervention; v) step-by-step procedure in the application of interventions;
l) implementation of the project results into guidelines and subsequent transfer into codes of practice and standards;
m) dissemination and exploitation of the results, quantification of the impact of the project on stakeholders, end-users, and public bodies charged with cultural heritage buildings maintenance and management.
Project results:
The exploitable results from the NIKER project can be roughly grouped into two main categories. The first category is constituted by the exploitable knowledge, meaning knowledge that has a potential for industrial or commercial application in research activities, or for developing new products or processes or services. The second category comprises the exploitable products and measures, which already constitute final objects, products or instructions that can be used by the end-users.
Taking into account the structure of the project and its final aim, related to the development of integrated methodologies to ensure the efficient protection with 'minimum intervention' of cultural heritage assets, with respect to the impact of earthquakes, the project results can be grouped as follows:
Exploitable knowledge
1. Creation of a new structured database that links earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques
The catalogue has been structured in an interactive, web-based form and is available online at http://niker.isqweb.it/ and will be soon directly linked from the main page of the project website http://www.niker.eu/ it has been developed by merging information deriving from literature survey and tests carried out during the project, and concerning:
- inventory of earthquake induced failure mechanisms related to construction types, structural elements and materials;
- critical review of retrofitting and reinforcement techniques related to possible failure mechanisms, requirements, performance parameters;
- critical review of methodologies and tools for assessment of failure mechanisms and interventions.
2. Experimental validation of the envisaged technological solutions for vertical and horizontal structural elements
The following structural elements and systems have been tested in original conditions, and the following materials / techniques for interventions have been developed and experimentally characterised, so as to find constitutive laws and develop design procedures for the strengthened elements:
- strengthening of multi-leaf stone masonry walls by means of hydraulic lime grouts and leaf-tying;
- strengthening of rammed earth, earth block and cob masonry walls by means of vertical textile belts;
- strengthening of adobe brick masonry walls by means of steel wire ropes mechanically fastened to the wall and disposed according to an X shape, geo-net PET or geo-nets PP;
- strengthening of dry brick walls by means of geo-nets PET and mortar;
- strengthening of solid brick masonry walls by means of steel wire ropes mechanically fastened to the wall and disposed according to an X shape;
- strengthening of wooden floors by means of double planking, panel consisting of long mineralised wood-wool bound, OSB panel, diagonal steel, wooden diagonal, composite diagonal and wooden of composite diagonal net;
- strengthening of arches and vaults by means of composite materials made with various types of fibers (steel, basalt, carbon) and mainly inorganic matrixes made of hydraulic lime mortar or epoxy matrixes.
In addition, compatibility, durability and effectiveness tests have been carried out on:
- the behaviour of solid clay bricks covered by a layer of externally applied FRP textiles, in case of forces normal to the reinforcements surface, based on performing pull-off tests;
- the behaviour of such reinforcements, in case of parallel forces reproducing their usual working conditions (fibres axially loaded and interface tangentially stressed); those tests are supposed to provide all the information required to characterise the local bond behaviour;
- the effect of humidity and of thermal cycles on the delamination of the FRP strips from the masonry support;
- the injectability of grout admixtures on stone masonry walls and the microstructural properties of the grout to original masonry material interface;
- the durability of natural hydraulic lime mortars.
3. Experimental quantitative characterisation of the behaviour of connections before and after strengthening
The following systems have been tested in original conditions, and the following techniques for interventions have been developed and experimentally characterised, so as to find constitutive laws and develop design procedures for the strengthened elements:
- strengthening of timber roof connections by means of dovetail halved joints;
- strengthening of wall-to-timber floor connections by means of timber lancing or grouted metallic anchors with hinged ends;
- strengthening of wall-to-wall connections by means of FRP / metallic bonded anchors, metallic ties with ductile anchorage system, grouted metallic anchors, grouted metallic anchors with hysteretic dissipative device and grouted metallic anchors with frictional dissipative device.
4. Development of test setups and testing strategies for sub-assemblies and experimental characterisation of the seismic behaviour of original substructures and substructures strengthened with integrated interventions by shaking table tests
The following structural elements and systems have been tested in original conditions and the following materials / techniques for interventions have been developed and experimentally characterised, so as to develop simultaneously the testing procedures and to find constitutive laws and develop design procedures:
- strengthening of multi-leaf stone masonry walls by means of hydraulic lime grouts and leaf-tying and of adobe walls and columns;
- strengthening of scaled earth block masonry buildings by means of different in-plane stiffness roof;
- strengthening of scaled subassemblies consisting of three piers made of three-leaf stone masonry, connected with a timber floor at their top by means of hydraulic lime grouts on the walls and different in-plane stiffness floors;
- strengthening of scaled subassemblies consisting of two piers made of hree-leaf stone masonry, connected with brick arches and cross vault.
5. Integration, validation and assessment of intervention techniques by experimental evaluation of overall seismic response of model buildings on shaking table
The model buildings have been tested in original conditions and after strengthening with hydraulic lime grouts on the multi-leaf stone masonry walls and enhancement of diaphragm action of floors.
6. Derivation, from the previous three points, of reliable models for connections and substructures; sensitivity study of buildings to quantify building seismic performance and response parameters to be used in seismic assessment and design; definition of optimised performance based design procedures related to overall building performance
In particular, it has been:
- derived design methods for vertical and horizontal structural elements and connections and for the overall seismic behaviour of buildings. Different typologies ranging from traditional houses to churches, representative of the cultural heritage asset, were considered and analysed;
- derived, from experimental tests and detailed numerical models, simplified and more complex models for in and out-of-plane behaviour of vertical elements, in-plane behaviour of floors, and longitudinal and transversal response of vaults to be implemented in global analyses;
- developed reliable numerical models of connections and substructures, made parametric assessment aimed at identifying interactions with repaired vertical and horizontal elements, defining optimised design procedures, carrying out sensitivity analyses based on the calibrated models. These analyses allowed studying the interactions of various conditions, as the state of the structural elements, state of the connections and boundary conditions;
- derived, from these analyses, simplified and more complex models of connections and substructures to be implemented in global analyses;
- integrated the above mentioned models and carry out sensitivity study of buildings according to geometry, intervention techniques, stiffness of horizontal elements and connections;
- quantified building seismic performance and response parameters to be used in seismic assessment and design.
7. Development of integrated methodologies that include:
i) monitoring as knowledge-based assessment and early warning tool;
ii) creation and update of reliable structural models;
iii) selection, design, and application of minimised interventions;
iv) evaluation of execution of intervention;
v) step-by-step procedure in the application of interventions.
The methodologies have been validated through application to 20 real case studies, selected to cover a wide and representative range of conditions regarding geographical location (different countries) local seismicity (low, medium, high), construction material (stone and brick masonry, earth), structural typologies and uses (towers and minarets, churches, large cathedrals, palaces), preservation condition (different levels of damage) and risks involved (i.e. people at risk, valuable artistic contents at risk).
This result was attained through several tasks involving:
- calibration of monitoring systems and devices;
- development of automatic systems for monitoring data-processing;
- development of targeted monitoring strategies and application of monitoring systems and devices for the identification of the real behaviour of buildings;
- application of the knowledge obtained through monitoring to the creation and updating of reliable structural models, to the definition of minimal interventions and to the evaluation of interventions;
- based on the previous evaluation, the optimal intervention techniques to selected case studies have been implemented, including the application of instrumented dissipative devices;
- conclusions on the effectiveness of the interventions and the corresponding optimal quality assessment procedures have been drawn.
Exploitable products:
1. Development of advanced materials and improved techniques for intervention on vertical and horizontal structural elements. Besides all the above mentioned technique, a direct industrial product development concerned the elaboration of grout mixtures with 10 % replacement of hydraulic lime with an ultrafine amorphous aluminosilicate, naturally occurred mineral of volcanic origin, processed in powderous form and more specifically 99,9 % of the mass of such processed aluminosilicate is below 45 µm.
2. Development of innovative intervention techniques for connections and of strengthening elements able to dissipate seismic energy
In particular, the new devices are:
- dissipative prototypes conceived as add-on for enhancing the performance of stainless steel ties. Hysteretic properties of a stainless steel element, shaped to optimise its post-elastic behaviour, or a friction mechanism set to be triggered for a certain level of pulling / pushing force, the dissipative devices allow small relative displacements, dissipating energy and hence reducing the impact of seismic force on the walls, and controlling damage;
- connection devices, which improves the connections between the structure of the floors and the resistant walls and can increase the safety of floors, and the global stability of the buildings, through the contribution of wooden floors to the bracing of the walls;
- connection between vertical structural elements, allowing them to stop working separately, as they start having a conjunct behaviour, made effective by installed rod. It Increases the deformation capacity and energy absorption of the structure, in case of horizontal loads (seismic), through the ductility that characterises the anchor plates. It can also be used as an element for preventing separation of structural elements (usually orthogonal).
3. Calibration of innovative measuring devices or systems, including embedded instruments in dissipative devices, on laboratory specimens and subsequent on-site application on real case studies
In particular, the newly developed product is a monitoring system consisting of a grouted stainless steel anchor coupled with a set of sensors and a data acquisition system. The system is conceived to be installed in a structure with the double function of repairing / strengthening and monitoring the response of both building and anchor. The sensors are designed to record a set of relative movements - vertical and horizontal, out-of-plane and in-plane - between the connected that are typical of common damage mechanisms - e.g. out-of-plane overturning.
4. Implementation of the project results into guidelines for an integrated applicability of the proposed methodologies and subsequent transfer into codes of practice and standards
The following documents have been produced and made available to the public:
- guidelines for design and execution of optimum interventions for end users;
- guidelines for assessment and improvement of connections and buildings for end-users;
- design and application guidelines for stick-slip and hysteretic dissipative anchors with embedded sensors;
- guidelines for reliable seismic analysis and knowledge based assessment of buildings;
- integrated methodology for effective protection and earthquake improvement of cultural heritage.
Potential impact:
The global objective of the project is to promote new sustainable and preventive strategies, concepts, integrated methodologies and techniques for protection of CH assets from earthquakes. The achievement of this main objective ensures to improve safety and, more in general, the quality of life of citizens and to improve the attractiveness of Europe, particularly its cities, buildings, and monuments.
All the techniques and materials that have been tested and validated within NIKER, have been also numerically reproduced and implemented into sophisticated models, that allowed gathering deeper knowledge on the behaviour of original and strengthened elements and of entire buildings. At the same time, modelling and analysis strategies and design methods for better interpreting the structural response and optimising the design process have been developed. The impact of these results to the efficient protection and preservation of CH is direct and transparent.
In addition, as earthquakes constitute the natural hazard that yearly causes the highest number of casualties in the world, it is clear that the practical application of the project results may turn in an increased safety, hence quality of life, for the society. So far, there has been an intense dissemination activity (carried out in regions recently hit by earthquakes, but not only), at a general public level, that allowed raising awareness to achieve rapidly the above-mentioned objectives. At the same time, intense dissemination of results at a stakeholder level (Ministry of Cultural Heritage, etc.), that has been carried out during the project and is being still carried out, allow planning of mitigation strategies that will have a strong impact on safety, quality of life, protection of CH and increase of related activities. As a demonstration, the Ministry of Cultural Heritage of Israel (IAA) is now starting working on a seismic risk plans on the basis of the NIKER outcomes, whereas the Ministry of Cultural Heritage in Italy (MiBAC) is resorting to the documentation produced within the NIKER project for making professional refresher courses for engineers and architects working on CH assets.
Another aspect of the developed technologies is that they are reliable, cost-efficient and knowledge-based. On one hand, the increased safety allows for a sustainable growth, as societies that are constantly coping with the consequences of natural disasters do not achieve sustained growth. On the other hand, the main approach of the project 'minimisation of interventions', by means of intense knowledge of the structure, allow reducing the use of resources and the impact on the environment, thus improving sustainability. As an example, the monitoring strategies developed and implemented allow, in certain cases, avoiding the execution of unnecessary interventions, thus implementing in practice the conservation principles. This has been demonstrated, e.g. in the case of the Arena of Verona, which has been monitored also during seismic shakings, on the basis of which records, the real state of damage and the updating of predictive numerical models has been done. The characterisation of techniques in terms of compatibility and long-term behaviour also has a primary role on sustainability, as this means making durable interventions on CH assets, which do not affect the environment, and which instead consume a minimum of resources. At the same time, this approach is based on technologies for knowledge, assessment, and design of new materials that favourably affect industrial competitiveness.
As regards the latter point, the technologies and methodologies developed within the project are cost-effective, optimised, assessed by real case studies and ready to be disseminated and exploited by means of application guidelines. Hence, by means of the NIKER project, the European construction industry, together with other service related SMEs, will achieve greater competitiveness, with a positive outcome on employment and the use / development of skills. The construction sector in particular, during the years of NIKER, has faced the worst crisis since the beginning of the modern era. It has been demonstrated that the further development of the Sector is limited by several shortcomings, particularly concerning the production of new structures. Hence, construction activities devoted to adaptive re-use, repair and maintenance are becoming a pillar of the sector.
This is also demonstrated by the lively presence, in the NIKER partnership, of four companies of the sector, plus two engineering firms. During the period, they have all expanded, or consolidated, the CH building related activities, with a clear countertrend with respect to the current economic overview. In most of the cases, the companies have been able to develop new materials and products within the project, and the service companies to increase their market share in reconstruction / restoration sector. In addition, all technologies covered within, mainly, WP9 (inspection and monitoring of buildings), will also have a direct contribution to European employment, as to meet these demands, structural assessment operators and service providers will have to employ more specialised staff.
Lastly, conservation of the existing CH is of vital importance for the maintenance and improvement of the tourism sector in Europe. Setting twenty different and very interesting case-studies in different countries has already had a media impact, with involvement and support of local authorities to the NIKER, which entailed direct involvement in the project of institutions that are also active in tourism promotion.
The active participation of countries beyond Europe allowed taking into account specificity of various CH assets and environmental conditions, ensuring transferability of results beyond the EU. Various tested systems and materials (e.g. timber framed walls, or earthen materials, etc.) are typically found in other countries. The collaboration of institutions coming from different countries on, and through, real case-studies, located in different places, has been of strong importance to set up relations and improve neighbouring countries and regional policies. The very active dissemination carried out at a national level by the project partners coming from ACs, ICPCs and MPCs has definitely helped in this sense. In addition, the project required a trans-national approach because it aims to solve problems common to most of Europe. Active cooperation of partners of different European countries on portions of the NIKER research activities has actually achieved the goal of increasing trans-national technological cooperation amongst Industry, SMEs, national and regional associations, and RTD-performers, that will profitably continue well beyond the NIKER project closure.
The project will also contribute to European standardisation and regulation. Research results can be included on one hand into the codes of practice of the managing authorities, and this is being already done through the public body participating in the NIKER partnership (IAA), but also with the many institutions involved during the project duration. On the other hand, research results can be included into the European codes, and this is also being already pursued, as demonstrated by the active participation of many partners in standardisation bodies (CEN TC 346 Conservation of Cultural Property; the various mirror group in the European countries as UNI - NORMAL in Italy, the international ISO TC98 SC2 WG6 - Heritage Structures, etc.), and in pre-normative technical committee (e.g. RILEM, where, as an example, the information derived on composite material application on masonry is being already introduced in TC 223-MSC 'Masonry Strengthening with Composite materials', where various NIKER partners are active).
The target group for the NIKER outputs are the end users, namely:
(a) those who manage the cultural heritage (public entities, bodies responsible of building maintenance, authorities, decision-makers);
(b) those who have the responsibility of choosing and designing the interventions on cultural heritage assets (designers, architects, engineers, consultancy firms);
(c) those who produce and apply the materials and technologies (mainly SMEs, Industry and construction companies);
(d) those who can further develop, study and propose the envisaged technologies (students and researchers).
On the other hand, the results arising from research are to be disseminated among the target groups listed above by means of:
(a) presentations at technical conferences and publication of papers;
(b) publication in technical and peer reviewed journals;
(c) promotion of training courses directed to professionals and contractors;
(d) presentation at commercial events and in specialist fairs;
(e) promotion of training and continuing education courses directed to professionals and technical and management staff of entities responsible of cultural heritage maintenance;
(f) presentation of the results at university academic courses, technical universities and teaching centres.
The first dissemination activities took place a couple of months before the beginning of the project: a specific web site with project information and potential access to project results (see http://www.niker.eu online) was made available in February 2010 (PM2) by the project coordinator, UNIPD.
An overall number of 316 dissemination actions have been carried out, which represents, on average, more than 8 monthly activities and around 6 dissemination activities per partner per year. These figures represent a deep commitment of the consortium in promoting and disseminating the research outputs.
The participation on conferences and meetings represents 46 % of the events, followed by the offer of training and academic courses, workshops and seminars, and academic thesis. It is especially worth to highlight that two common Special Sessions were organised together with the PERPETUATE project, aiming at presenting the most recent developments within both projects in an integrated way. These two special sessions were organised in the framework of two important international conferences in the field of earthquake engineering and cultural heritage conservation: the 15th World Conference in Earthquake Engineering (15th WCEE), 24 to 28 September, 2012 Lisbon, Portugal and the 8th International Conference on Structural Analysis of Historical Constructions (SAHC 2012), 15 to 17 October 2012, Wroclaw, Poland.
The dissemination level, according to the type of target group and to the type of action carried out, can be regional, national or international. From the 316 dissemination activities, an average of 50 % of the actions was carried out at national level in the countries involved in the project. It is worth to note that 19 % of the actions had a regional emphasis, as the creation of a network of capillary dissemination at local level (i.e. direct contact with end users) is very important for the success of the tools under development. A relatively good balance has been reached so far between national / international actions as well as between regional / national ones. 19 % of the dissemination actions have been carried out outside the countries of the consortium. Partners did an important effort to create impact at international level, but focused in their countries, so the results can effectively be transferred to end-users. It is also hoped that this effort will allow the development of new cooperative projects inside Europe and the Mediterranean basin, as a continuation of the NIKER project.
The target groups of the dissemination activities were mainly constituted by scientists and researchers (37 %), followed by architects, engineers and professional bodies (27 %), and university and training organisations (25 %). Architects, engineers and professional bodies are also important secondary target groups, together with scientists and researchers, university and training organisations and general public. This scenario shows that the NIKER outputs are welcome both by the scientific community and professionals. Furthermore, MSc and PhD students (as future highly qualified professionals) are also benefiting from the project results.
The results of the project (in terms of both knowledge and products) will be exploitable by all the partners involved in the consortium, each one in accordance with its own field of activity.
The new structured database developed under WP3 enables to link earthquake induced failure mechanisms, construction types and materials, interventions and assessment techniques. In a more detailed way, the database allows:
(a) generating new cross-correlations between key factors as ductility and energy dissipation capacity, allowing using the most recent state-of-the-art knowledge;
(b) fixing design parameters and requirements, for interactive development of materials and techniques;
(c) defining the performance levels needed for advanced design of interventions.
These results constitute a powerful exploitable knowledge, as no database of this kind has been elaborated before. The database has been loaded with basis on results from peer-reviewed published literature.
As most of the experimental testing procedures adopted within the NIKER project are not yet standardised, the results obtained can be used for the improvement of laboratory testing setups and procedures, for fixing pre-normative recommendations in the field. Therefore, these testing setups and procedures constitute a relevant exploitable knowledge as they will be used in near future as standard procedures by the scientific community. A good example is the publication of a journal paper about the execution of bond tests on brick masonry specimens strengthened with composite materials.
The numerical modelling gives as a result the definition of suitable modelling strategies for the historical masonry structures of different material and geometric complexity and an assessed way for defining the key mechanical parameters. The novelty of the numerical approach followed stands also in the complementary use of different modelling approaches and in the simultaneous definition of modelling procedures for different types of masonry structures, which provides a considerable broad view of the problem.
The developed guidelines characterise the design and execution of innovative intervention technologies on vertical and horizontal elements. The various techniques described in the documents present details on materials, design rules and relation with possible failure mechanisms and damages. The guidelines suggest also optimum intervention for improvement of seismic performance of vertical and horizontal elements.
The multidisciplinary nature of interventions on cultural heritage presents a high complexity for professionals to achieve the necessary knowledge to support making decisions. In this sense, the procedure required to support and control an adequate decision making process, aimed at the selection of correct interventions, is also addressed in the guidelines.
Throughout the project, also innovative products and techniques have been developed and they do represent a step forward, in the sense that can be looked at as an incorporation of scientific knowledge. Thus, they represent also an important competitive, technical and economic added-value for the companies involved in civil and seismic engineering and CH protection. In this sense, companies will be able to sell an all-inclusive package, providing both the products and the design of the required intervention.
Bozza Legnami was mainly involved in the reinforcement of wooden floors, proposing and comparing several solutions of in-plane structural strengthening. The added value of the research lies in the given first classification of in-plane strengthening, which led to the elaboration of a quantitative positioning of the rigidity of the proposed intervention. The key features of this kind of intervention are the possibility of a dry strengthening solution, the lightness of the reinforcement and the high adaptability to existing or new buildings, against a cost which is in line with the one of similar interventions already in use. The reversibility of the intervention is of main importance as it concerns cultural heritage, since it is a core principle required by the government authority. The company will further develop this research in order to outline a simplified methodology for the identification of the correct intervention techniques to be used according to the conservation status and to the dynamic response of the existent masonry buildings with wooden floors. It is envisaged that the results of this research would be implemented into computing software for the use of sector professionals.
The prototype for the dissipative anchoring device and the innovative monitoring anchoring device would benefit Cintec's competitiveness, whose 40 % of the turnover is in the heritage building market.
The dissipative prototypes are conceived as add-on for enhancing the performance of stainless steel ties. Cross-ties are indeed able to provide a connection at the joints of perpendicular sets of walls, where poor quality, previous damage or general wear and tear may facilitate crack onset and eventually out-of-plane failure. Thus, they meet the requirement of restoring the box-like behaviour of masonry structures, allowing for the redistribution of horizontal load in sets of perpendicular walls without substantially increasing the mass. Nonetheless, anchors can also cause pull-out damage at the head of the anchorage and increase in-plane diagonal cracking because of the different deformability of steel and masonry. This might become a major problem when damage limitation should be pursued, avoiding cracking in precious plasters, frescoes, and other culturally valuable finishes. Thanks to either the hysteretic properties of a stainless steel element, shaped to optimise its post-elastic behaviour, or a friction mechanism set to be triggered for a certain level of pulling/pushing force, the dissipative devices allow small relative displacements, dissipating energy and hence reducing the impact of seismic force on the walls, and controlling damage.
On the other hand, the monitoring system consists of a grouted stainless steel anchor coupled with a set of sensors and a data acquisition system. It relies on CINTEC's technology and is conceived to be installed in a structure with the double function of repairing / strengthening and monitoring the response of both building and anchor. The purpose is to have a continuous monitoring of the system over either a short period immediately after a major earthquake and before the design of the permanent repairs, or in the long term as control of the performance of the strengthen structure and as an early warning system for future strong motion occurrences. Recorded data can be correlated to determine the evolution of damage to the portion of structure where the anchor is installed as consequence of micro- tremors, relative settlements in the ground, and so on. Whereas a standard monitoring system detects the response of a structure at a global level, the instrumented anchor can capture localised phenomena. The system is designed and assembled in house so that installation of a number of separate sensors is avoided, reducing the amount of resources needed and the risks for contractors working on site. The sensors are designed to record a set of relative movements (vertical and horizontal, out-of-plane and in-plane) between the connected that are typical of common damage mechanisms. On the basis of the recorded data, preliminary conclusions can be drawn on whether the temporary strengthening is sufficient to ensure a certain seismic response of the structure or whether other interventions are required. Once the system is fully calibrated, software for the analysis of the recorded data and the comparison with a set of limit values is developed, so that in the case of urgent interventions, when data are required in a short time, the whole process of monitoring is simplified.
S&B developed µ-SILICA, an ultrafine amorphous aluminosilicate, naturally occurred mineral of volcanic origin, processed in powderous form. It has many innovative features such as: low water demand, low content in water soluble alkalis, natural pozzolan-compatibility with the initial building materials, off white colour, easy to use in mortars and generally restoration works, it lowers permeability on chloride, low CO2 footprint. Grout mixtures using µ-SILICA proved to have increased long term strengths, better resistance to salt crystallisation, lower shrinkage, more sustainable design mix. Following the development of the aforementioned innovative solution within the NIKER project, the company estimates to increase its market share in the restoration industry (where now S&B's position is almost negligible), increasing its own turnover and export, as well as strengthening its brand.
Monumenta developed some connection devices with high potential of application on site and relevant contribute in the scope of global reinforcement solution for ancient buildings. These devices are also highly compatible with the original construction design of old buildings (low-intrusiveness), are lighter and easier to apply (when compared with other solutions) and therefore the interventions based on these devices should be faster and cheaper than it generally is. The use of these devices, combined or not, allows to achieve satisfactory results regarding the structural behaviour of existing ancient buildings using an alternative approach to the reinforcement solutions that are nowadays commonly in use.
This new approach should be enhanced and presented to the main job promoters and designers, as aspects like economy of resources (human, natural, time, energy, etc.) and the respect of the identity of those buildings (because of its low-intrusiveness) are very important for the acceptance of this alternative methodology. Intensive and efficient marketing activities must be carried out in order to show (from the financial, sustainability and social points of view) that the use of these devices, once combined, can replace, in some scenarios, the use of other 'heavier' techniques / solutions.
Besides the developed guidelines and products, another important impact of the NIKER project is associated to the decision making and educational processes within bodies appointed for cultural heritage management and maintenance. Their direct or indirect involvement in the project raises awareness about the need for knowledge-based scientific approaches and methodologies in the protection of cultural heritage and use of seismic risk mapping. The case of IAA is a very good example about the setting of governmental priorities and policies in the area of cultural heritage.
The knowledge achieved within the project, through the case-studies in Bosnia-Herzegovina, improved the understanding of the seismic behaviour of stone masonry traditional minarets, raising the level of competitiveness and the scope of future research and commercial activities for IPM.
ZRS can take advantage of an analogue worked out knowledge for earthen materials (mechanical properties, methods for strengthening with assessment of effects and limits of use) achieved through the case study on the Preceptory in Ambel, Spain. The developed knowledge obtained within the scope of NIKER was already used in projects, realised by or in corporation with ZRS. The improved knowledge about earthquake induced risks and possible protection measures, not only for earthen buildings in particular but also in general, is a competitive advantage and has led to project requests among others in Iraq and Colombia.
Finally, the different dissemination activities carried out at different levels, such as the publication of academic theses, the participation in conferences and exhibitions, the organisation of workshops, the publication of technical and scientific papers, etc., constitute both an exploitable knowledge and product of the research. These actions can be seen as foundations on which further research carried out especially by RTDs will be based on. Publications and communications inside the scientific community are a very powerful way to enrich the project results with other people experience and to make the scientific community aware of the project results to help them identifying future research needs.
Project website: http://www.niker.eu
UNIPD:
Prof. Claudio Modena
claudio.modena@unipd.it
Tel/fax: +39 049 827 5613
BAM:
Dr Patrick Fontana
patrick.fontana@bam.de
Tel: +49-308-1041712
ITAM:
Prof. Milo Drdácký
drdacky@itam.cas.cz
Tel: +42-028-3880854
NTUA:
Prof. Elizabeth Vintzileou
elvintz@central.ntua.gr
Tel: +30-210-7721272
POLIMI:
Dr Antonella Saisi
saisi@stru.polimi.it
Tel: +39-022-3994386
UMINHO:
Prof. Paulo Lourenço
pbl@civil.uminho.pt
Tel: +35-125-3510209
UPC:
Prof. Pere Roca
pere.roca.fabregat@upc.edu
Tel: +34-934-017381
UBATH:
Prof. Dina D'Ayala
d.d'ayala@ucl.ac.uk
GUNI:
Prof. Ali Ihsan Unay
unay@metu.edu.tr
Tel: +90-312-5823658
ENA:
Prof. Khalid El Harrouni
kelharrouni@gmail.com
Tel: +21-266-1374150
CDCU:
Prof. Mona Fouad Alì
monalyeg@yahoo.com
Tel: +20-237-349449
IAA:
Mr Jacques Neguer
jacque@israntique.org.il
Tel: + 97-235-042275
BOZZA:
Mr Enzo Bozza
info@bozzalegnami.it
Tel: +39-049-629699
CINTEC:
Mr Dennis Lee
dennislee@cintec.co.uk
Tel: +44-163-3246614
IMP:
Mr Mustafa Humo
mhumo@interprojekt.ba
Tel: +38-736-555132
S&B:
Mr Thanasis Karalis
T.Karalis@sandb.com
Tel: +30-210-6296177
ZRS:
Dr Christof Ziegert
ziegert@zrs-berlin.de
Tel: +49-303-98009531
MONU:
Mr Vítor Cóias
vitorcoias@gestip.pt
Tel: +35-121-3712580