考虑不同加载路径退化的RC柱恢复力模型参数分析及改进

Parametric analysis and improvement of hysteretic model for reinforced concrete column with deterioration behaviors under different loading paths

  • 摘要: 结构抗地震倒塌评估要求构件恢复力模型区分不同加载路径退化行为。既有区分不同加载路径退化的RC柱恢复力模型,其参数校准依赖的试验数据多集中高强混凝土、高轴压比及高配筋率工况,难以反映中低层RC框架结构的关键参数特征,导致在该类结构中适用性受限。为提高中低层RC框架结构抗倒塌评估精度,本文系统研究了现有模型对该类结构力学行为模拟的准确性。构建了符合中低层RC框架结构关键参数特征(低强度、低轴压比和低配筋率)的RC柱试验数据库;综合均值预测及不确定性双指标,利用物理机制解释和统计分析结合,基于新建数据库评估了既有模型参数公式的准确性,结果表明弹性参数公式预测不确定性较小,准确性较高,非线性参数公式存在系统性明显低估;对误差显著及缺失的非线性参数公式改进和补充,给出了改进RC柱恢复力模型。试验验证表明,改进模型充分考虑了中低层RC框架结构的低强度、低轴压比和低配筋率的参数特征,可更准确模拟结构地震倒塌失效全过程力学行为。

     

    Abstract: Collapse assessment requires component hysteretic model that accurately captures deterioration behaviors under different loading paths. The existing path-dependent RC column hysteretic model relies on parameter calibration derived predominantly from experimental data with high-strength concrete, high axial compression ratios (ACR), and high reinforcement ratios. These data mismatch fail to represent critical parameter characteristics of low- to mid-rise RC frame structures, limiting applicability. To enhance collapse assessment accuracy for such structures, this study systematically evaluates existing models’ accuracy in simulating mechanical behavior of such structures. An RC column experimental database reflecting key structural characteristics (low-strength, low ACR, low reinforcement ratios) was established. Using the dual metrics of prediction mean and uncertainty, and combining physical mechanism interpretation with statistical analysis, the predictive accuracy of existing model parameter formulas were evaluated based on established database. Results demonstrate that elastic parameter formulas exhibit lower uncertainty and higher accuracy, while nonlinear formulas show significant underestimation. Consequently, error-prone and missing nonlinear formulas were improved and supplemented, yielding the improved RC column hysteretic model. Experimental validation confirms the improved model adequately incorporates low-strength, low-ACR, low-reinforcement design features, enabling more accurate simulation of mechanical behavior throughout the seismic collapse process, from elastic response to deterioration and failure.

     

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