The need to mitigate the risk associated with seismic vulnerability of CH assets and the possibility of nowadays technologies, in terms of materials, processes, design tools, etc, in reducing damage and losses due to cracking and failure under seismic excitations is unquestionable. However, in contrast to the expectations, some defects that make useless the effects of the interventions and even increase the vulnerability of CH assets can arise for various reasons, such as:
- The use of inadequate materials that give rise to chemical, physical and mechanical incompatibility with the existing ones;
- The use of inadequate intervention techniques that alter significantly the original bearing system of the structure and/or are based on concepts that were proven to be reliable in case of modern structures and are applied (without prior validation) to historic structures as well. To mention an example, measures to ensure infinitely rigid diaphragms at floor and roof levels or to significantly enhance the ductility of an historic structure do not necessarily affect in a positive way the seismic behaviour of the building.
- The above risks may be dramatically increased by inadequate analysis of historic structures. The problems arising here are related to analyses performed on the basis of limited information regarding the original structural system; the use of unsuitable analytical tools; the adoption of behaviour models developed for modern structures. Furthermore, very often, dated design methods, which do not reflect the actual strengthening technique as they are based on rule-ofthumb and/or odd material properties, are applied. Finally, it has to be noted the tendency of applying to CH assets the increased design seismic actions adopted in Europe and elsewhere for new structures, and the lack of adequate education of consultants and practitioners in the field of technologies for protecting CH.
Potential damages on CH assets are currently too high, as regards the social (casualties), cultural (loss of artistic value) and economic losses, mostly due to the above reasons related to intrinsic CH assets vulnerability, and to the fact that most of the technologies applied to date to reduce this vulnerability are too intrusive, cost-inefficient, and often unreliable and/or non-effective. This also reflects in disuse of CH assets, that implies further worsening of their condition, increase of burden for stake-holders, owners, and bodies appointed for CH management and maintenance, and loss of competitiveness of SMEs and construction sector, because of wrong or ineffective solutions proposed.
The NIKER project proposes the development of a new integrated methodology for solving the above-mentioned problems, aiming at improving the general safety level and for reducing the loss of artistic value, where the increased participation of end-users and the formulation of new competitive solutions to the construction sector are fostered. Such a methodology does inevitably relay on a multidisciplinary approach for the development of innovative materials and systems for low-intrusiveness, compatible interventions. The methodology makes use of nanotechnology for the development of mortars and grouts, taking also into account the substrate they are meant to be applied to. It is based on innovative use of Steel Reinforced Polymers/Steel Reinforced Grout (SRP/SRG) materials; on the definition of new application methods and design rules for Fiber Reinforced Polymers (FRP); on the development of compatible techniques for horizontal elements and connections; on the advance of innovative dissipative devices for anchors and tying. This requires the creation of a database of information based on new multi-levelled relational models. The database will assist the tasks of developing materials and technologies with simultaneous setting out and characterization, of advancing in design and minimization of application, of improving the solutions for seismic risk mitigation and structural enhancement with environmental requirements, of introducing innovative tools for knowledge based assessment and early warning. All these factors converge for innovation and conservation in CH.
Thus, on the basis of real application conditions, the project aims at developing and validating complete and diversified innovative technologies and tools for systemic improvement of seismic behaviour of CH assets. Those materials and technologies will ensures at once effectiveness, economic application and maintenance, low-intrusiveness towards the existing structure, respect of authenticity and of the original structural concept, and high structural performance and improvement of seismic behaviour. It optimizes also the collaboration between old and new materials and elements, the sensitivity and compatibility of the intervention solving the still existing technical problems. Furthermore, the project intends to provide modern and sound design methods, early warning techniques for intelligent interventions and advanced monitoring techniques for knowledge-based assessment and progressive implementation and evaluation of interventions. The final objective is to enable cost-efficient and reliable mitigation of potential damages to CH assets caused by earthquakes.