| dc.description.abstract | Ph.D. Thesis proposes a Soft-Computing approach capable of supporting the engineer judgement in the selection and
design of the cheapest solution for seismic retrofitting of existing RC framed structure. Chapter 1 points out the need for
strengthening the existing buildings as one of the main way of decreasing economic and life losses as direct
consequences of earthquake disasters. Moreover, it proposes a wide, but not-exhaustive, list of the most frequently
observed deficiencies contributing to the vulnerability of concrete buildings. Chapter 2 collects the state of practice on
seismic analysis methods for the assessment the safety of the existing buildings within the framework of a performancebased
design. The most common approaches for modeling the material plasticity in the frame non-linear analysis are
also reviewed. Chapter 3 presents a wide state of practice on the retrofitting strategies, intended as preventive measures
aimed at mitigating the effect of a future earthquake by a) decreasing the seismic hazard demands; b) improving the
dynamic characteristics supplied to the existing building. The chapter presents also a list of retrofitting systems,
intended as technical interventions commonly classified into local intervention (also known “member-level”
techniques) and global intervention (also called “structure-level” techniques) that might be used in synergistic
combination to achieve the adopted strategy. In particular, the available approaches and the common criteria,
respectively for selecting an optimum retrofit strategy and an optimal system are discussed. Chapter 4 highlights the
usefulness of the Soft-Computing methods as efficient tools for providing “objective” answer in reasonable time for
complex situation governed by approximation and imprecision. In particular, Chapter 4 collects the applications found
in the scientific literature for Fuzzy Logic, Artificial Neural Network and Evolutionary Computing in the fields of
structural and earthquake engineering with a taxonomic classification of the problems in modeling, simulation and
optimization. Chapter 5 “translates” the search for the cheapest retrofitting system into a constrained optimization
problem. To this end, the chapter includes a formulation of a novel procedure that assembles a numerical model for
seismic assessment of framed structures within a Soft-Computing-driven optimization algorithm capable to minimize
the objective function defined as the total initial cost of intervention. The main components required to assemble the
procedure are described in the chapter: the optimization algorithm (Genetic Algorithm); the simulation framework
(OpenSees); and the software environment (Matlab). Chapter 6 describes step-by-step the flow-chart of the proposed
procedure and it focuses on the main implementation aspects and working details, ranging from a clever initialization of
the population of candidate solutions up to a proposal of tuning procedure for the genetic parameters. Chapter 7
discusses numerical examples, where the Soft-Computing procedure is applied to the model of multi-storey RC frames
obtained through simulated design. A total of fifteen “scenarios” are studied in order to assess its “robustness” to
changes in input data. Finally, Chapter 8, on the base of the outcomes observed, summarizes the capabilities of the
proposed procedure, yet highlighting its “limitations” at the current state of development. Some possible modifications
are discussed to enhance its efficiency and completeness. [edited by author] | it_IT |
