FE Modeling of Non-circular LRS FRP-Confined Concrete Columns
FE Modeling of Non-circular LRS FRP-Confined Concrete Columns
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DOI：
10.1016/j.compstruct.2022.115314
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发表时间：
2022-01
影响因子：
6.3
通讯作者：
M. Mohammadi;Y. Bai;Hongbiao Yang;G. Lin;J. Dai;Yu-Feng Zhang
中科院分区：
文献类型：
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作者：
M. Mohammadi;Y. Bai;Hongbiao Yang;G. Lin;J. Dai;Yu-Feng Zhang
在大断裂应变（LRS）纤维增强聚合物（FRP）约束混凝土柱中，LRS FRP通过提供被动侧限压力，以与传统FRP相同的机理提高混凝土柱的强度和延性。然而，LRS FRP表现出比常规FRP大得多的应变能力。值得注意的是，LRS FRP具有双线性材料刚度，而不是传统FRP中的线性刚度。因此，在轴压下，LRS FRP约束混凝土将承担不同的荷载路径相比，传统的FRP约束。这种差异必须考虑LRS FRP约束柱的有限元分析（FEA），特别是当约束压力是不均匀的。为此，对23根LRS FRP约束混凝土异形柱进行了单调轴压试验和分析。可变测试参数是纵横比（即，横截面的深度（长边）和宽度（短边））、LRS FRP层的数量以及LRS FRP的类型。对于有限元分析，混凝土损伤塑性模量（CDPM）分别采用主动约束压力法和约束刚度法进行标定。主动约束压力法表明，LRSFRP约束混凝土的塑性流动主要由LRSFRP夹套的次刚度决定。对于约束刚度法，混凝土塑性流动是由LRS FRP夹套约束圆柱的压缩循环试验推导出的约束刚度的函数。结果表明，LRS FRP约束混凝土的塑性膨胀角的变化几乎是普通FRP约束混凝土的3倍。几何效应被包含在所得到的塑性膨胀角，使一个新的塑性膨胀角模型成为可行的非圆形LRS FRP约束混凝土柱的有限元分析。利用这种新的塑性膨胀角模型，使建议的塑性损伤模型，以捕捉应力应变行为的非圆形柱。此外，合理地捕捉了截面上塑性流动的不均匀性。
In concrete columns confined with large rupture strain (LRS) fiber-reinforced polymers (FRPs), the LRS FRPs enhance the strength and ductility of concrete columns with the same mechanism as conventional FRPs by rendering passive lateral confinement pressure. However, LRS FRPs exhibit a strain capacity much larger than that of conventional FRPs. Notably, LRS FRPs have a bilinear material stiffness instead of the linear stiffness in conventional FRPs. Therefore, under axial compression, concrete confined by LRS FRPs will bear a different load path compared to that confined by conventional FRPs. This difference must be considered for finite element analysis (FEA) of LRS FRP-confined columns especially when the confinement pressure is non-uniform. To this aim, 23 samples of non-circular LRS FRP-confined concrete columns under axial monotonic compression were tested and analyzed. The variable test parameters are the aspect ratio (i.e., the depth (longer side) and width (shorter side) of the cross-sections), the number of LRS FRP layers, and the type of LRS FRPs. For FEA, the concrete damage plasticity module (CDPM) was calibrated by both the active confinement pressure approach and the confinement stiffness approach. The active confinement pressure approach shows that the concrete plastic flow of LRS FRP-confined concrete is dominated by the secondary stiffness of the LRS FRP jacket. For the confinement stiffness approach, the concrete plastic flow is deduced from the compressive cyclic tests of cylindrical columns confined by LRS FRP jackets as a function of confinement stiffness. Results showed that the plastic dilation angle of concrete confined by LRS FRPs changes almost three times faster than that for concrete confined by conventional FRPs. The geometrical effects are included in the obtained plastic dilation angle so that a new plastic dilation angle model becomes feasible for the FEA of non-circular LRS FRP-confined concrete columns. Utilizing this new plastic dilation angle model enables the proposed plastic damage model to capture the stress strain behavior of the non-circular columns. Moreover, the non-uniformity of plastic flow on sections is captured reasonably.