钢纤维混凝土试验及单轴抗拉本构模型研究

Study on Steel Fiber Reinforced Concrete Test and Uniaxial Tensile Constitutive Model

  • 摘要: 通过单点加载切口梁试验,获得钢纤维混凝土构件荷载-裂口宽度曲线,并据此建立弯拉本构模型;通过修正弓形钢纤维混凝土弯拉强度与抗拉强度转换关系,提出钢纤维混凝土单轴抗拉本构模型;同时,采用有限元数值模拟,获得该模型作用下钢纤维混凝土的破坏形态、损伤演化规律和荷载-挠度曲线,结合压弯试验结果,分析弓形钢纤维混凝土的增韧、增强机理。研究表明,钢纤维混凝土切口梁破坏时,大多钢纤维被拉脱且端部的弯钩被拉直,弓形钢纤维对混凝土构件弯拉强度有二次增强作用,以25 kg/m3为基准,钢纤维掺量增加5 kg/m3、10 kg/m3、15 kg/m3时,弯拉强度二次峰值增幅分别达到20.4%、28.57%、12.04%;弓形钢纤维混凝土在破坏形态和损伤演化方面,分别呈现出钢纤维被拉直和裂缝多、间距小且长度短的特点,表现出了更高的韧性;与普通混凝土相比,弓形钢纤维混凝土荷载-挠度曲线在弹性段后出现了纤维增强段,直观展现出弓形钢纤维混凝土更高的强度和韧性。模型的数值模拟计算结果与试验结果高度吻合,验证了模型可靠性。

     

    Abstract: The load-crack width curve of steel fiber reinforced concrete components is obtained from the single point loading test on the notched beam, and a flexural-tensile constitutive model is established based on this curve.The uniaxial tensile constitutive model of steel fiber reinforced concrete is proposed by modifying the conversion relationship between flexural-tensile strength and tensile strength of hooked steel fiber reinforced concrete. At the same time, finite element numerical simulation is used to obtain the failure mode, damage evolution law, and loaddeflection curve of steel fiber reinforced concrete under the action of this model. In combination with the results of the compression and bending test, the toughening and strengthening mechanism of hooked steel fiber reinforced concrete is analyzed. The study shows that when the notched steel fiber reinforced concrete beam is damaged, most of the steel fibers is pulled off and the hooks at the ends are pulled to be straight. Hooked steel fiber has a secondary strengthening effect on the flexural tensile strength of concrete components. By taking 25 kg/m3 as the benchmark,when the steel fiber content increases by 5 kg/m3, 10 kg/m3 and 15 kg/m3, the secondary peaks in the flexural-tensile strength are increased by 20.4%, 28.57% and 12.04%, respectively. In terms of failure mode and damage evolution, the hooked steel fiber reinforced concrete exhibits the characteristics of steel fiber being straightened and many cracks, small spacing and length, respectively, which shows its higher toughness. Compared with ordinary concrete,the load-deflection curve of the hooked steel fiber reinforced concrete shows a fiber reinforced section after the elastic section, intuitively demonstrating higher strength and toughness of the hooked steel fiber reinforced concrete.The numerical simulation results of the model are highly consistent with the test results, verifying the reliability of the model.

     

/

返回文章
返回