Regulatory framework for structural assessment
Regulatory framework for structural assessment
Francesco Romeo, Università degli Studi di Roma “La Sapienza”
Evaluating the safety of existing buildings of historical and artistic interest is a highly complex issue as it requires balancing technical, economic, and social factors. From a purely technical perspective, the assessment aims to ensure, based on quantitative criteria, that the performance level of the structure and its components is above the minimum required for their structural safety and functionality. In terms of socioeconomic aspects, a probabilistic approach is now taken to consider the extent of direct losses, i.e., damage to the building, indirect losses, i.e., damage to the contents and activities, and the loss of human life. When the loss of cultural value is also considered, the difficulty of converting engineering factors that describe the performance of buildings into a single risk index to quantify the various losses becomes apparent. The assessment of existing structures often requires the application of refined methods that are beyond the scope of design codes for new structures. In Europe new European technical rules will be developed to cover the assessment, re-use and retrofitting of existing structures, in keeping with the principles and fundamental requirements of the EN Eurocodes. In Italy, evaluation activities are primarily governed by two regulations: the NTC 2018, or Technical Standards for Construction, and Circular no. 7 of 21 January 2019, which contains the application guidelines. According to these regulations, the safety assessment of existing buildings must, as far as possible, be carried out in relation to the requirements for new buildings. In the case of heritage reinforced concrete structures, for which is worth mobilizing residual load bearing capacity to minimize or avoid interventions, specific technical regulations are not yet available. Only recently, in the fib Model Code 2020, within the overarching sustainability-oriented approach, the cultural heritage aspect is mentioned among the social performance requirements. In particular, in Chapter 8 “Principles of Conservation”, it is mentioned that special performance requirements may be defined for special structures, such as heritage structures. Special performance requirements, such as preservation of structural and architectural features in the structures, may restrict the types of intervention which can be undertaken. Specific fib guidelines, harmonised with Model Code 2020, are currently under development.
