Manager: Marichela Sepe

Key words: Sustainable modelling, materials, structures, urban spaces

Abstract

The proposed research project aims at merging skills and knowledge through a collaborative research activity among the involved research units in the field of i) analytical and numerical modelling of reliable constitutive laws, to predict the response up to failure (collapse) of the most relevant building materials used in structural design. Traditional materials (such as concrete and masonry) and innovative ones (such as nano-additivated concrete and mortar are considered. Inter-relationships with ii) urban and economic/legal context are also included in the project. From the i)th point of view, damage in FRCM-masonry elements can occur with very different features (debonding inside the substrate, debonding at FRCM-substrate interface, debonding at the fiber-matrix interface, fiber slippage, fiber slippage with cracking of the mortar, tensile rupture of the fiber). Each of these behaviour is characterized by a different constitutive law which has to be identified and related to each other. The modeling strategy is based on fully nonlinear analyses of traditional and historical buildings by means of Finite Element strategies. The state of the art on the subject denotes a strong need to provide innovative structural modelling methodologies based on simplified approaches able to simulate the nonlinear behavior of historical masonry buildings and to provide reliable results with a reasonable computational effort. There are several proposals for a detailed numerical simulation of FRCM-masonry interaction considering a uniaxial nonlinear behaviour and accounting for all the possible damage mechanisms which may occur with very different features. Single layer interfaces, usually adopted in three-dimensional general purpose software environments, are not suitable for a proper simulation of such a complex behaviour, and there is the need of introducing multi-layer interfaces properly calibrated. On the other side, for multistorey frame structures, the reduction of complex structural systems, such as multi-storey frame buildings, to simplified equivalent beam models has been adopted by many researchers in the scientific literature and is still an open challenge of great interest. In particular the modeling of buildings showing some kind of irregularity needs to be improved and developed. Large structures are usually studied by means of Finite Element approaches. They are still often studied in the linear field only. When the nonlinear behaviour is accounted for, huge computational efforts are needed, usually not compatible with practical engineers’ needs. Hence, nonlinear ultrasonic techniques more sensitive to the concrete material degradation during its early stage of damage, will be considered to bring clear advantages in view of preventing collapses as well as of designing prompt and effective strengthening interventions for structural members. As far as second ii) topic is concerned in connection with the first one, the concept of urban quality is widely analysed in planning studies. It has to do with the construction of the city and its various components: buildings, mobility networks, public spaces, equipment. Quality is associated with the physical conditions of the urban system and of its individual sections. It also extends to the basic components that allow the construction of the urban organism. The quality level is accompanied by a parallel (and reverse) level of degradation. The risk is the combination of the probability of an event and the damage expected from the event itself. In urban planning, the risk is interpreted as the result of the potential stresses that can affect a specific area (the danger), the quantity, value or type of elements invested (exposure) and their tendency to damage (vulnerability). The multiple risk in an urban system can be affected by the combination of several risks, including the social-economic one, whose study is at initial stage. Over the last two centuries, the city as a unitary system has expanded and shattered into urban sectors displaying very different characteristics. Urban analysis is the basis of the subsequent planning phase. The differentiation between urban sectors derives from various parameters (among others, time of formation, social structure, quality of the built, functional destination) which, in turn, influence the level of risk of each of them. The areas characterized by structural degradation of buildings, abandoned and little accessible public spaces, and cultural heritage in a poor state of conservation require integrated and flexible interventions. The current methods of analysis and design of buildings and sites are devoted to only identifying single elements or analysing single aspects of them.