不同应变率下聚甲醛纤维机场道面混凝土弯曲性能研究

机场道面混凝土结构在不同性质荷载作用下的力学行为受应变率的影响较大。为研究应变率对聚甲醛纤维机场道面混凝土(PFAPC)弯曲性能的影响,通过四点弯曲试验,分析不同应变率(10^-5~10^-1 s^-1)下PFAPC抗弯挠度、弯曲模量、弯曲强度及韧性指数的变化规律,并观察断口纤维的微观形貌,总结不同应变率下的纤维失效模式。结果表明:PFAPC的弯曲峰值强度、极限抗弯挠度及弯曲模量随应变率的增加呈上升趋势;与峰值强度相比,应变率对PFAPC残余强度影响较小,但随应变率增大总体呈上升趋势;与极限抗弯挠度相比,峰值挠度随应变率的增加波动上升;聚甲醛纤维在各应变率作用下主要为拔出破坏模式;PFAPC在车辆及飞机冲击作用下能吸收较大能量,呈现出一定的延性破坏特征,具有良好的弯曲韧性。

Bending Properties of Polyoxymethylene Fiber Airport Pavement Concrete under Different Strain Rates

The mechanical behavior of airport pavement concrete structure under different loads is greatly affected by strain rate. In order to study the effect of strain rate on the bending properties of polyoxymethylene fiber airport pavement concrete (PFAPC), the bending deflection, bending modulus, bending strength and toughness index of PFAPC under different strain rates (10^-5~10^-1 s^-1) were analyzed by four-point bending test, and the microstructure of fracture fibers was observed and the failure mode of fibers under different strain rates was summarized. The test results show that the bending peak strength, ultimate bending deflection, and bending modulus of PFAPC increase with the increase of strain rate. Compared with the peak strength, the strain rate has little effect on the residual strength of PFAPC, but the overall trend is upward with the increase of strain rate. Compared with the ultimate bending deflection, the peak deflection fluctuates with the increase of strain rate. The bending modulus increases with the increase of strain rate. The polyoxymethylene fiber is mainly in the pull-out failure mode under the action of each strain rate. PFAPC absorbs a large amount of energy under the impact of vehicles and aircraft, showing a certain ductile failure characteristics, and a good bending toughness.