超高性能混凝土功能梯度复合梁抗弯性能研究

Flexural Behavior of Ultra-High Performance Concrete Functionally Graded Composite Beams

为研究超高性能混凝土功能梯度复合梁(UFGCB)的抗弯承载力,设计6组UFGCB和1组普通钢筋混凝土(RC)梁。通过四点弯曲试验,以超高性能混凝土(UHPC)功能层厚度与UHPC抗拉强度为设计参数,对UFGCB破坏形态、抗弯承载力以及延性进行分析。结果表明:UHPC中纤维桥联作用及纤维拉拔过程中的能量耗散促使UFGCB表现出延性破坏特征。UFGCB的抗弯承载力和延性相较于RC梁试件显著提高,且随UHPC厚度的增加,UFGCB的抗弯承载力逐渐增大,延性先增大后减小。UHPC抗拉强度过高不利于UHPC和混凝土的协同工作能力,会造成UFGCB抗弯承载力的减小和延性降低。依据正截面承载力分析理论,建立UFGCB抗弯承载力计算公式,计算值与试验值吻合较好。

In order to study the flexural capacity of ultra-high performance concrete functional graded composite beams(UFGCB), six groups of UFGCB and one group of RC beams were designed. Through four-point bending test, the failure mode, flexural capacity and ductility of UFGCB were analyzed with the thickness of UHPC functional layer and tensile strength of UHPC as design parameters. The results show that UFGCB exhibits ductile failure due to fiber bridging and energy dissipation during fiber drawing. The flexural capacity and ductility of UFGCB are significantly higher than those of the RC beams. The flexural capacity of UFGCB increases with the increase of UHPC thickness, with the ductility first increasing before decreasing later. An excessively high tensile strength of UHPC is not conducive to the synergy of UHPC and concrete, which can reduce the flexural capacity and ductility of UFGCB. A flexural capacity calculation model of the UFGCB was established based on the analysis theory of normal section bearing capacity with the calculated values being in good agreement with the experimental ones.