Projects / Programmes
Optimized planning of sustainable retrofitting actions for preservation of historical monuments and building heritage.
| Code |
Science |
Field |
Subfield |
| 2.01.00 |
Engineering sciences and technologies |
Civil engineering |
|
| Code |
Science |
Field |
| T220 |
Technological sciences |
Civil engineering, hydraulic engineering, offshore technology, soil mechanics |
Cultural heritage, historical structures, masonry structures, numerical analysis, in-situ tests, optimization of costs, guidelines and recommendations
Researchers (11)
Organisations (3)
Abstract
Efficient revitalization of historical structures requires multi disciplinary approach. Hence, designer has to have deep knowledge of anamnesis of particular building (history of building and damage history), to postulate adequate diagnosis (interpretation of damages, crack patterns as well as results of in-situ tests), to determine therapy (repair, strengthening and retrofitting actions) and to prescribe control of implemented actions (monitoring). Due to conservator's demands regarding the preservation of the architectural identity of the building, structural engineers are usually limited solely on repair actions. With this approach mechanical resistance of the structure (MRS) can not be significantly increased. Requirements of contemporary European standards regarding load bearing capacity of the structure are (in the most cases) not achievable for historical structures (thus most of the European national standards for historical structures impose much lower values for MRS). Furthermore, actions for the improvements of MRS recommended by contemporary European standards are in the most cases from the point of view of conservators not acceptable. For them appropriate methodology in preservation of historical buildings and other building heritage would be application of sustainable reversible retrofitting actions with the compliance of aesthetic appearance and architectural identity of the structure. In the first phase of the project primary goal will be to determine how deep knowledge of the structure is required for its structural evaluation, which methods should be used for that purpose and how the amount of collected data from the site may influence the evaluation of vulnerability index of historical structures. Within this part of the project, influence of injection grouts (based on lime binder) on the seismic resistance of masonry walls will be evaluated through laboratory and in-situ shear tests. What may be the beneffit from sustainable retrofitting actions on the evaluation of structural response due to the different loading conditions (seismic, settlements, change of use etc.), will be evaluated through the second phase of the project. Here different safety factors for structures will be evaluated depending from the chosen numerical model (from simpliest to most sophisticated i.e. from force method to FEM). Results of parametric studies (case studies) will represent a solid base for cost-benefit analysis of the whole process of evaluation of historical structures (diagnosis – analysis – retrofitting). Main goal of proposed research project will be preparation of guidelines and recommendations for the efficient revitalization of historical masonry structures by means of sustainable retrofitting actions and considering their financial effect.
Significance for science
The purpose of the present work is to contribute to the establishment of standards and methodology of work in the field of strengthening multiple leaf stone and stone-brick walls with lime based grout injection, where such standards do not exist. This is especially problematic in case of grout injection of heritage buildings walls, where, because of strict requirements and limitations, there is a necessity of supplementary research and directions, both in planning and in actual execution of the work. At first the rules and the needed research to determine the state and the type of stone masonry are presented. Criteria and the list of the research to determine the characteristics of dry, fresh and hardened injection grout is given. At the end, guidelines to assure the quality control of the work are presented. The first part of the research is represented by preliminary research that consists of four segments. In each segment, criteria are given, on base of which grouts are positioned in quality classes A, B and C. Criteria for grouts are defined upon agreement between producers of grouts, artistic conservators and experts from this research group. In the fourth segment of the preliminary research, cylindrical specimens that represent the strengthened internal core of the wall are analysed as well.
The second part of the research is practical, »in situ« application of selected injection grouts (four types) in strengthening of chosen stone masonry walls by means of grout injection technique. In the scope of in-situ tests different techniques were used to characterize unstrengthen and strengthened walls: GRP, IR thermography, sonic tests, single and double flat jack, probing and boroscopy, crack pattern survey. To determine the quality of grouting, the possibility of combining results from GPR (ground penetrating radar) and IR (infra-red) thermography methods is shown. In the last part of the work, guidelines for quality execution of strengthening by means of grout injection technique are presented.
Numerical part encompass experimentally supported seismic assessment of cultural heritage assets depending from the type of the structure and levels of knowledge. Till now there were no systematic analysis on CH structures.
Analysis of different methods for the evaluation of the vulnerability of CH structures. Within this context, the results from kinematic methods were compared with the results gained with non-linear methods. The results of both approaches are comparable (depending from the considered parameter), but it is necessary to be aware of the limits of applied methods and sometimes to combine different methods to obtain efficient revitalisation of the structure.
Parametric analysis of different non-linear models for the assessment of seismic resistance of stone masonry buildings (house, palace, church, tower). Assessment of the seismic resistance of buildings considering storey mechanisms vs. global response mechanisms. Defining efficiency of proposed models by comparison of gained failure mechanisms with observed on-site, following seismic event.
Optimization of strengthening methods for the revitalization of CH structures in dependence from the knowledge level and methodology for seismic assessment.
Significance for the country
Results of proposed research project may influence better preserving of cultural heritage of Republic of Slovenia. Till now, full cooperation was establish between key partners in the proces of preserving our cultural heritage assets: ZVKDS as end user and as responsible partner for determing conservators demand, GI ZRMK as civil eng. company responsible for implementation of works and UL FGG as research partner. Results of present work, represent solid ground for the implementation of gained knowledge from research field into practice.
Results of proposed project will represent a solid ground for the implementation of new “Law for the protection of cultural heritage” as well as for the preparation of national documents for the implementation of European standards – EC 8–1-3. Through EU project PERPETUATE, where European guidelines for evaluation and mitigation of seismic risk to cultural heritage are going to be prepared, Slovenian aspect will be considered as well.
Restoration works that will be oriented towards domestic sources of materials will increase demand for such materials that will have an impact on local producers and suppliers. All used materials till now were domestic. Qualitative and methodically evaluated restoration works on particular object, will have an impact on better condition of the structure, long term lower costs of maintenance and higher quality of living in that building.
Some of the methods for diagnostic of historical building may represent opportunity for local SME’s, so it may open a new market for them. Preliminary results of in-situ tests show significant increase of shear resistance of masonry injected with cement and lime based grouts. Depending from the observed problem, different combinations of NDT and MDT together with DT methods were calibrated.
Till now waste majority of CH buildings were analyzed considering storey mechanisms. There were no comparative analysis of non-linear models for storey vs. global mechanisms. Through this project a new method was introduced – kinematic method for the evaluation of local mechanisms of failure. This method is efficient for city centres with high seismic risk.
Transfer of the knowledge from European projects into Slovenian practice.
Education of new professionals:
Two young researchers from UL Faculty of civil engineering and geodesy and one researcher from the Institute for matematics, physics and mechanics are involved in project activities through their postgraduate studies.
Through diploma and master degree thesis following students from FGG were involved:
URANJEK, Mojmir. Problems in case of grout injection of heritage buildings walls : master of science thesis., 2008. XIII, 146 str., ilustr. 1 optični disk (CD-ROM). [COBISS.SI-ID 4320097] – mentor V.Bosiljkov
KRŽAN, Meta. Parametric seismic esistance of Kolizej in Ljubljana : graduation thesis. 2008. XXIV, 95 str., pril., ilustr. 1 optični disk (CD ROM). [COBISS.SI-ID 4246113] – mentor V.Bosiljkov
NOVAK, Sandi. Optimized planning of retrofitting actions for preservation of historical monuments ž case study of Pišece castle : graduation thesis., 2008. X, 78 str., ilustr. 1 optični disk (CD-ROM). [COBISS.SI-ID 4290145] – mentor V.Bosiljkov
VIDALI, Anja. Immovable cultural heritage: case study of Piran music hause : graduation thesis, 2008. IX f., 65 str., pril., ilustr. 1 optični disk (CD-ROM). [COBISS.SI-ID 3952993] – komentor V.Bosiljkov
NAGLIČ, Ana. Seismic analysis of regious buildings : graduation thesis. Ljubljana: [A. Naglič], 2011. XIX, 146 str., ilustr. [COBISS.SI-ID 5289825]
SEVŠEK, Mojca. »Vulnerability seismic assessment of stone masonry buildings in Posočje region by kinematic method« – foreseen for May 2011.
Prešern's grant UL FGG:
COTIČ, Patricia. Experimentally supported parametric non linear seismic analysis of stone masonry buliding, under supervision of doc. dr. Vlatka Bosiljkova and Mete Kržan. Ljubljana: [P. Cotič], 2010. XIX, 115 str., ilustr. [COBISS.SI-ID 52173
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