剪力钉构造措施对UHPC模板-现浇NC界面黏结性能的影响

Effect of shear key arrangement on the bonding properties of prefabricated UHPC-NC interface

  • 摘要: 为了研究预制超高性能混凝土UHPC与普通混凝土(NC)界面的黏结滑移性能,以预制UHPC表面剪力钉的密度和分布间距为试验参数,完成了12组UHPC-NC复合试件的双面剪切试验。结果表明,设置剪力钉构造措施的试件其破坏形态主要有3种,分别为(a) UHPC-NC黏结面与UHPC剪力钉均发生剪切破坏;(b) UHPC-NC黏结面剪切破坏、UHPC剪力钉同时发生剪切和剥离破坏;(c) UHPC-NC黏结面剪切破坏、NC基体轴压破坏。剪力钉密度与分布间距对UHPC-NC试件的黏结面抗剪强度有显著影响;尤其是剪力钉密度,黏结面抗剪强度随着剪力钉密度呈抛物线增长关系。在相同剪力钉密度下,剪力钉分布间距较大试件的黏结面抗剪强度比间距较小试件提高了19.04%~41.74%。基于现有模型及试验结果,建立了考虑黏结面破坏形态及抗剪试验方法的预制UHPC-NC黏结面抗剪强度的计算公式,其计算值与试验值吻合度较高,可为UHPC-NC复合试件的界面设计提供参考。

     

    Abstract: In order to study the bond-slip behavior of the interface between prefabricated ultra-high performance concrete (UHPC) and normal concrete (NC), 12 sets of UHPC-NC bond specimens were tested using double-sided shear tests with the density and spacing of shear studs on the prefabricated UHPC surface as the experimental parameters. The results show that, after the shear studs being installed on the formwork, there are three main failure modes of the specimens, namely (a) shear failure of UHPC-NC bond surface and UHPC shear studs; (b) shear failure of UHPC-NC bond surface and simultaneous shear and peeling failure of UHPC shear studs; and (c) shear failure of UHPC-NC bond surface and axial compression failure of NC matrix. The density and distribution interval of shear studs have a significant impact on the shear strength of UHPC-NC bond surface, especially the shear stud density. The shear strength on the bond surface increases parabolically with the density of shear studs. Under the same density of shear stud, the specimens with larger distribution interval of shear stud have a 19.04%-41.74% increase in shear strength on the bond surface, compared to the specimens with smaller distribution interval. On the basis of existing models and experimental results, a calculation formula for the shear strength of prefabricated UHPC-NC bond surface is established. It considers the failure modes of bond surface and the shear testing methods. The calculated results are in good agreement with the experimental values. This can provide a reference for the interface design of UHPC-NC composite specimens.

     

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