带肋SMA筋与ECC粘结性能影响因素试验及本构模型

Experimental investigation on factors affecting the bonding properties and constitutive model of ECC and ribbed SMA bars

  • 摘要: 国内外对于具有形状记忆效应的形状记忆合金(Shape memory alloy,简称SMA)以及具有应变硬化、多缝开裂特性的工程水泥基复合材料(Engineered cementitious composite,简称ECC)在工程领域的应用进行了广泛的研究,发现应用上述两种材料可以有效减小地震对结构的损伤。通过设计25组单调和循环荷载下的中心拉拔试验对带肋SMA筋与ECC的粘结滑移性能进行了研究。研究表明,试验试件的破坏形式有拔出破坏和拔出-劈裂破坏两种形式。带肋SMA筋与ECC的粘结性能相较光圆SMA更优异;保护层厚度的增大和ECC强度的增强可以显著提升试件的极限粘结强度,保护层厚度从2 d增大到4.5 d能提升31%的粘结强度,基材从E30提升至E50后则能够提升30%的粘结强度;而随着带肋SMA筋直径从6 mm增加到10 mm和锚固长度从5 d增加到10 d,试件的极限粘结强度则会分别减小23%和28%;循环荷载下粘结强度会提升12%,且呈现明显的恢复性能;基于试验数据进行拟合分析,提出了适用于带肋SMA筋与ECC的粘结应力-滑移本构模型和锚固长度公式。

     

    Abstract: Extensive research has been conducted on the utilization of shape memory alloys (SMA) with shape memory effect and engineered cementitious composites with strain-hardening and multi-seam cracking characteristics in the field of engineering. The study was conducted through 25 sets of central pull-out tests under monotonic and cyclic loading to investigate the bond-slip behavior between ribbed SMA bars and engineered cementitious composite (ECC). The findings indicated two primary failure modes: pull-out failure and pull-out-splitting failure. The ribbed SMA bars demonstrate superior bond performance with ECC compared to smooth SMA bars. Increasing the cover thickness and enhancing ECC strength significantly improve the ultimate bond strength. Specifically, expanding the cover thickness from 2 d to 4.5 d results in a 31% bond strength improvement, while upgrading the matrix strength from E30 to E50 achieves a 30% enhancement. Conversely, enlarging the bar diameter from 6 mm to 10 mm reduces the ultimate bond strength by 23%, and extending the anchorage length from 5 d to 10 d causes a 28% reduction. Under cyclic loading conditions, the bond strength exhibits a 12% enhancement and demonstrates notable recovery characteristics. Through systematic analysis of experimental data, a constitutive bond stress-slip model and anchorage length formula were established specifically for ribbed SMA bars embedded in ECC.

     

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