engleski

EXPERIENCES IN THE STRUCTURAL ANALYSIS AND SAFETY ASSESMENT OF HERITAGE BUILDINGS IN CROATIA

In the structural analysis of heritage buildings each specific case presents a new challenge and requires a particular approach that considerably differs from the regular every-day design practise. Specifically, existing structural configurations need to be analysed, frequently without adequate documentation regarding the structural concept, the verification of load-bearing elements and the construction process. Further uncertainties arise due to the structure’s history that may include a number of unknown impacts due to various events of natural or man-made origin, such as earthquake actions, ground settlements, temperature changes, fire, explosion or war destruction. Moreover, poorly documented previous interventions during the lifespan of the structure may cause additional difficulties in the application of appropriate assessment methods. Furthermore, geometric features of historical structures are usually rather complex and available material properties may not always be fully reliable. Considering also certain deficiencies in contemporary engineering education approaches, as well as limitations of codified procedures and legal constraints, substantial difficulties in the protection of cultural heritage buildings from the structural point of view may be identified. Nevertheless, multidisciplinary teams of experts from different research areas, working closely together and depending strongly on each other, are commonly formed nowadays, at least for monuments of particular importance. Hence, significant improvements have been achieved regarding the prevention of inappropriate structural interventions, which may cause irreversible damage to valuable heritage buildings due to inadequate decisions. Indeed, multidisciplinary investigations clearly support structural engineers in the attempt to resolve specific structural issues, accounting at the same time for other important aspects. Available data is typically collected with the aim to establish numerical models, which are regularly being considered the most effective tool for the analysis of structural systems. However, even the implementation of the most sophisticated and detailed state-of-the-art modelling approaches does not automatically ensure a satisfactory structural safety assessment, especially due to the fact that the expected results in the case of historical structures may be particularly sensitive to the given input parameters. Therefore, experienced structural engineers regularly adopt a range of numerical models at different refinement levels, including not only complex solid models, but also simpler frame and shell models or even fundamental graphic procedures, which were possibly adopted for simple verifications in the construction period and can be exceptionally useful for a complete understanding of the structural behaviour. Such approach may be essential for the approximation of the real stress distribution and after all, for the evaluation of appropriate safety coefficients in order to formulate adequate retrofit strategies. Within the scope of this work, problems which may be faced in the safety assessment of typical heritage buildings in Croatia are analysed through four examples of different structural complexity, i.e., the Monastery Sv. Jakov, the Martinušić Palace, the Đorđić Palace and the atrium of the Rector’s Palace in Dubrovnik. The significant role of structural engineers is stressed, since their knowledge, experience and acuity are of extraordinary importance for the effective implementation of available data from different disciplines, leading to satisfactory final decisions and beneficial overall results.

Structural analysis; Numerical modelling; Laboratory tests; Multidisciplinary approach; Acuity; Clinical eye

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