As it is well known, Poisson’s ratio of concrete is not constant during a loading process, but increases with increasing compressive loading. In this study, the effect of Poisson’s ratio and its variation on the compressive behavior of FRP-confined concrete is investigated using finite element (FE) analysis. The concrete triaxial behavior was modeled using plasticity theory and damage mechanics. Buckling of longitudinal rebars and bending of transverse rebars were included in the model. Because of the software limitations for applying the variation of Poisson’s ratio during the loading process, a stepwise procedure is proposed. For the sake of verification and corroboration of the results, for column samples under different confining and reinforcing conditions, the available test data in literature were examined. The data set contains 25 FRP-confined normal strength concrete columns with different number of FRP layers with or without steel reinforcement. The results of this study demonstrate the importance of considering the variation of Poisson’s ratio in 3D finite element analysis of confined concrete. Comparing the results obtained from the proposed model with the available test results in the literature shows that the average absolute error (AAE) of the proposed model is less than 14% with standard deviation (SD) of 6.16%. Therefore, the capability of this model in estimation of the entire compressive stress–strain curve of concrete columns over a wide range of confining conditions is acceptable.

中文翻译：

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考虑泊松比变化的FRP约束混凝土柱压应力-应变曲线预测

众所周知，混凝土的泊松比在加载过程中不是恒定的，而是随着压缩载荷的增加而增加。在这项研究中，泊松比及其变化对 FRP 约束混凝土的压缩行为的影响使用有限元 (FE) 分析进行了研究。混凝土三轴行为使用塑性理论和损伤力学建模。模型中包括纵向钢筋的屈曲和横向钢筋的弯曲。由于在加载过程中应用泊松比变化的软件限制，提出了逐步程序。为了对结果进行验证和确证，对不同围压和加固条件下的柱样，查阅了文献中已有的试验数据。该数据集包含 25 个 FRP 约束的普通强度混凝土柱，具有不同数量的 FRP 层，有或没有钢筋。这项研究的结果证明了在约束混凝土的 3D 有限元分析中考虑泊松比变化的重要性。将提出的模型获得的结果与文献中可用的测试结果进行比较，表明该模型的平均绝对误差（AAE）小于 14%，标准偏差（SD）为 6.16%。因此，该模型在广泛的约束条件下估计混凝土柱的整个压应力-应变曲线的能力是可以接受的。这项研究的结果证明了在约束混凝土的 3D 有限元分析中考虑泊松比变化的重要性。将提出的模型获得的结果与文献中可用的测试结果进行比较，表明该模型的平均绝对误差（AAE）小于 14%，标准偏差（SD）为 6.16%。因此，该模型在广泛的约束条件下估计混凝土柱的整个压应力-应变曲线的能力是可以接受的。这项研究的结果证明了在约束混凝土的 3D 有限元分析中考虑泊松比变化的重要性。将提出的模型获得的结果与文献中可用的测试结果进行比较，表明该模型的平均绝对误差（AAE）小于 14%，标准偏差（SD）为 6.16%。因此，该模型在广泛的约束条件下估计混凝土柱的整个压应力-应变曲线的能力是可以接受的。将提出的模型获得的结果与文献中可用的测试结果进行比较，表明该模型的平均绝对误差（AAE）小于 14%，标准偏差（SD）为 6.16%。因此，该模型在广泛的约束条件下估计混凝土柱的整个压应力 - 应变曲线的能力是可以接受的。将提出的模型获得的结果与文献中可用的测试结果进行比较，表明该模型的平均绝对误差（AAE）小于 14%，标准偏差（SD）为 6.16%。因此，该模型在广泛的约束条件下估计混凝土柱的整个压应力-应变曲线的能力是可以接受的。