HYPOTHESIS FOR AN APPLICATION OF THE FACTOR METHOD TO REINFORCED CONCRETE

The research is collocated in the general field of the studies on life cycle management for building components and especially on the durability of reinforced concrete. In particular, in reference to Factor Method, introduced in norm ISO 15686 for the ESL prediction, the objective of this study is to suggest a methodology aimed to the reduction of subjectivity in the determination of the multiplying factor for this specific component. Factor Method currently represents the instrument that is probably used the most for the estimation of the life cycle of building components, also thanks to its adaptability and simplicity. Yet, the most frequent critics that are moved against this method are indeed tied – in addition to those against the criteria for RSL determination – to the excessive subjectivity for the appreciation of multiplying factors. In view of mandatory and voluntary legislation of the last years (referring, for example to UNI-EN 206-1 and to UNI 11104 which derived from it, or to D.M. 14/01/2008 and to EC2:2005) which contributed to provide useful elements of comparative and absolute evaluation, but also on the spur of some suggestions that were formulated during recent years in the worldwide scientific scene, the research suggests – in the aim of evaluating service life for structures in reinforced concrete – in its first part the definition of a set of values of reference (among which the values to use for the specific case can be chosen) corresponding to the parameters that are considered to have influence on each multiplying factor. Then, in the second part, in order to simplify the assignment of the scores to the users, the conditions of unitary value for each parameter have been identified, considering the results of direct observations carried out on the field in the last decades. Eventually, starting from unitary values, a complete grid of values has been defined, containing the values to attribute to worsening and improving conditions. The results obtained in the research can represent for designers a possibility of application of Factor Method without risks of oscillation between too distant and subjective values, due to the uncertainty in adopting more appropriate scores.