Abstract
In this study, a multi-objective Genetic Algorithm (GA) optimization procedure is proposed for the seismic retrofitting of Reinforced Concrete (RC) building frames via Fiber-Reinforced Polymer (FRP) jackets. The optimization problem is solved via numerically efficient but accurate Finite-Element (FE) models able to take into account the strengthening and ductility increase contribution for a given FRP jacketing configuration. Based on a reference RC frame case study, an optimization approach aimed to maximize the frame ductility and minimize the FRP volume/cost is proposed, by taking into account different FRP jackets thicknesses for the internal and external columns and well as for each separate frame floor. In doing so, careful consideration is paid also to the expected collapse mechanism for the frame and the approach to embed a further objective able to control the collapse mechanism into the procedure is described. The results show the potential of the approach, which not only provides the entire Pareto Front of the multi-objective optimization problem, but also allows for general considerations about the influence of the design variables on the response of a given RC building.
Highlights
A Genetic Algorithm optimization procedure has been proposed for the seismic retrofitting of Reinforced Concrete (RC) building frames via FiberReinforced Polymer (FRP) jackets
The thickness of the Fiber-Reinforced Polymers (FRP) jackets was set as main design variable, including the option that different FRP thicknesses were allowed for internal/external columns as well as at each frame floor
For the RC frame considered as case study, in particular, strengthening the first floor internal columns resulted the solution able to lead to the best compromise between ductility increase and minimum retrofitting cost
Summary
The use of Fiber-Reinforced Polymers (FRP) in civil engineering applications represents a well-established technique in current practice. The goals of the multiobjective optimization analysis are given by (i) maximization of the RC frame ductility and (ii) minimization of the volume ( the cost) of FRP jackets, by taking into account the current provisions of the seismic design standards in use for concrete structures (i.e., maximum inter-storey drift ratio (EN1998-1, 2004)). Objectives and constraints for the general case of the optimal design of retrofitting for RC frames by means of FRP jackets will be described. The parametric FE simulations were carried out via advanced, numerically efficient but accurate numerical models able to properly take into account the FRP-jacketing effects on the overall seismic performance of a given RC frame. For each FE model, two different optimization analyses were carried out depending on the horizontal load distributions, i.e., a first-mode proportional distribution (D1) and a mass-proportional distribution over the frame height (D2)
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More From: American Journal of Engineering and Applied Sciences
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