考虑黏结-滑移效应的UHPC梁裂缝宽度计算方法

Calculation method for crack width of UHPC beams considering bond slip effect

为建立适用于配筋超高性能混凝土(UHPC)梁的裂缝宽度计算公式,提出了考虑黏结-滑移效应的裂缝宽度计算方法。以钢纤维掺量、配筋率和保护层厚度为参变量,通过10片UHPC-T形截面梁的四点抗弯试验,研究了各参变量对试验梁破坏形态和最大裂缝宽度的影响规律。应用基于微元体建立的平衡与变形微分控制方程,结合考虑多影响因素的界面黏结-滑移关系,建立了配筋UHPC梁的裂缝宽度计算公式。通过与试验值、文献值对比,验证了裂缝宽度计算公式的正确性与适用性。结果表明:建立的裂缝宽度计算公式能充分体现钢纤维抗拉贡献和钢筋与UHPC界面间的黏结-滑移性能影响,其计算值与试验值吻合良好,能准确计算配筋UHPC梁的裂缝宽度。

To establish a crack width calculation formula applicable to reinforced ultra-high performance concrete(UHPC) beams,a crack width calculation method considering bond slip effects was proposed.Based on the four-point flexural tests of 10 UHPC-T beams with steel fiber content,reinforcement ratio and protective layer thickness as parameters,the effects of each parameter on the failure pattern and maximum crack width of the test beams were studied.The equations for calculating the crack width of reinforced UHPC beams were established by using the balance and deformation differential governing equations based on microelements and the interfacial bond slip relation considering many influential factors.The correctness and applicability of the formula for calculating crack width were verified by comparing with the experimental and literature values.The results show that the established formula can fully reflect the tensile contribution of steel fiber and the influence of interface bonding and sliding properties of steel bar and UHPC.The calculated values are in good agreement with the experimental values,and the crack widths of reinforced UHPC beams can be accurately calculated.