چكيده به لاتين
Experiments have shown that during loading the Poisson's ratio of concrete increases with increasing compressive load. However, in many previous studies, until the concrete reaches the breaking point, that's Poisson's ratio is assumed to be a constant value, generally choosing 0.2. However, this value varies due to some factors such as the failure of the concrete in the inelastic region. In this study, it is attempted to predict the behavior of FRP- surrounded concrete in terms of Poisson's ratio variations.
For this purpose, FRP- surrounded reinforced concrete specimens were studied under non-linear finite element method using Abaqus software. The triaxial behavior of concrete was modeled using theories of plasticity and damage mechanics. A step-by-step approach was proposed to simulate the confined elements more precisely and to model Poisson's ratio variations during loading. In this method, an intermediate range is proposed between the two values of the initial and final Poisson's ratio. Parameters related to this interface pattern were calculated by the optimization process using coding in MATLAB software. Based on the results, a mathematical equation was estimated to obtain the model parameters. The proposed model is capable of predicting complete stress-strain diagram of FRP- surrounded concrete samples.
In order to validate the proposed model, the results of the proposed method were compared with the experimental results. Then, two error measures were considered to show the difference between theoretical and experimental stress-strain graphs. The results showed that the proposed model is very accurate for evaluating the stress-strain response of FRP encapsulated concrete.
