短切玄武岩纤维对钢筋混凝土梁抗弯性能的增强效果试验研究

Experimental Research on Flexural Properties of Chopped Basalt Fiber Reinforced Concrete Beams

将玄武岩纤维作为增强材料掺入到混凝土基材中形成水泥复合材料,即为玄武岩纤维增强混凝土(BFRC)。以玄武岩纤维长径比为试验变量,开展了BFRC梁的四点弯曲静力加载试验,研究其在受弯过程中的力学行为以及玄武岩纤维的增强效果;基于所收集的纤维混凝土材料力学性能试验数据,建立纤维混凝土抗拉、抗压强度与基体混凝土抗压强度、纤维掺量、纤维长径比之间的关系,并基于既有RC梁的特征承载力计算模型,提出适用于BFRC梁的特征承载力预测模型。研究结果表明:BFRC梁均满足平截面假定,玄武岩纤维的加入对BFRC梁开裂和极限承载力有提高作用,其中长径比为1200的BFRC梁特征承载力提高最为明显;同时玄武岩纤维的掺入增加了裂缝条数,抵抗裂缝向高度方向发展,并使其截面弯曲刚度增大;提出的BFRC梁改良特征承载力预测模型的计算结果与试验结果拟合程度良好,能较好地预测BFRC梁的开裂、极限承载力,并能反映纤维在混凝土梁中的增益作用。

Basalt fiber is added into the concrete substrate as a reinforcing material to form a cement composite which calls basalt fiber reinforced concrete(BFRC).Taking the aspect ratio of basalt fiber as the test variable,the four-point bending static loading test for BFRC beams was carried out to study its mechanical behavior and the reinforcement effect of basalt fiber;based on the collected mechanical property test data of fiber reinforced concrete,the relations between the tensile and compressive strength of fiber reinforced concrete and the compressive strength of matrix concrete,fiber content and fiber length diameter ratio was established,the prediction model of characteristic bearing capacity of BFRC beam was proposed based on RC beam model.The results showed that BFRC beams could meet the plane section assumption,and the addition of basalt fiber could improve the cracking and ultimate bearing capacity of BFRC beams,among which the characteristic bearing capacity of BFRC beams with length diameter ratio of 1200 was the most obvious;at the same time,the addition of basalt fiber could reduce the maximum crack width,increase the number of cracks and increase the bending stiffness of the beam;the calculation results of the improved characteristic bearing capacity prediction model of BFRC beams proposed in the paper could fit well with the test results,which could better predict the cracking and ultimate bearing capacity of BFRC beams,and reflect the gain effect of fiber in concrete beams.