超高延性混凝土仿生梁弯曲性能及其理论模型

Flexural Behavior of Bio-inspired Beams Using Ultra-high Ductile Concrete and Its Theoretical Model

摘要:

参照贝壳珍珠母的微观多级分层组装形式，在宏观尺度下进行了仿生分层设计，使用超高延性混凝土（UHDC）制作了一系列梁试件。先通过轴拉、轴压试验获取了UHDC的拉压本构关系。再通过4点弯曲试验，对其分层梁弯曲性能进行了详细研究。试验结果表明：直接堆叠UHDC梁的抗弯强度达16.75 MPa，是直接浇筑UHDC梁的1.34倍；当挠跨比为1/50时，所有仿生分层梁均体现出优异的变形能力、韧度和耗能能力；仿生分层梁还表现出与贝壳珍珠母类似的层间滑移和裂缝偏转等破坏模式。最后，结合UHDC的本构关系和4点弯曲试验结果，提出了分层梁的理论计算模型，并与试验结果进行对比，验证了模型的合理性。

Abstract:

Based on the hierarchical micro-structure of nacre， this study developed a bio-hierarchically stacking method at a macro-scale. A series of beams were fabricated using ultra-high ductile concrete （UHDC）. Uniaxial tensile and compressive tests were conducted to obtain the constitutive model of UHDC. Four-point bending tests were carried out to investigate the flexural property of the stacked beams. The results indicate that the flexural strength of directly stacked beam reaches 16.75 MPa， which is 1.34 times of that of monolithically cast beam. All hierarchically stacked beams exhibit superior deformability， toughness and energy dissipation capacity， even though the deflection/span ration reaches as high as 1/50. Moreover， interlamellar sliding and cracking branching are also observed on the hierarchically stacked beams， which are similar to the failure model of nacre. Finally， a theoretical model was proposed based on the constitutive model of UHDC and verified by comparing the experimental results and theoretical results.