聚乙烯醇纤维增强水泥复合材料板的冲切性能

Punching performance of polyvinyl alcohol fiber reinforced cementitious composite slab

利用MTS试验机对聚乙烯醇纤维(PVA)/水泥复合材料板进行准静态冲切试验,研究了不同PVA纤维掺量对其破坏形态和承载力的影响。结果表明:掺入PVA纤维能够将水泥基板的破坏形态由脆性破坏转为延性破坏。PVA/水泥复合材料板的冲切极限荷载和耗能能力均随PVA纤维掺量增加而增大,其中耗能能力的增大更显著。进一步采用Instron落锤冲击系统对PVA纤维体积分数为2vol%的PVA/水泥复合材料板进行动力冲切试验,研究冲切速度(2.0~4.2 m/s)对PVA/水泥复合材料板的破坏形态、初裂荷载、极限荷载、初始刚度及耗能性能的影响。结果表明:与准静态试验相比,冲切荷载作用下PVA/水泥复合材料板的极限荷载增大,而耗能减少;此外相对初裂荷载和耗能,极限荷载的冲切速度相关性最显著。基于上述结果,构建了纤维增强水泥复合材料四线型拉伸本构模型,并通过反算模型和塑性铰线方法对纤维增强水泥复合材料板的冲切力学性能进行模拟,并得到材料的本构参数。本研究可以为PVA/水泥复合材料的抗冲切设计提供技术支撑。

A quasi-static punching test was conducted on polyvinyl alcohol(PVA)fiber/cementitious composite slab by using MTS testing machine.The effects of the PVA fiber content on the failure mode and bearing capacity of PVA/cementitious composite slab were studied based on the experimental results.The results show that incorporating of PVA fiber can change the failure mode of the PVA/cementitious composite slab from brittle failure to ductile failure.And both the punching capacity and the energy absorption capacity of the PVA/cementitious composite slab increase with the fiber content and more obvious rise can be observed for the energy absorption capacity.Then the dynamic punching test of PVA reinforced cementitious composite slab with 2 vol%volume fraction of PVA was carried out by using Instron dropweight impact system.The influences of the impact velocity(2.0–4.2 m/s)on the failure mode,cracking impact loading,ultimate impact loading,initial stiffness and energy absorption capacity of the PVA/cementitious composite slab were investigated.The results show that compared with the results from the quasi-static test,the ultimate loading of the PVA/cementitious composite slab increases while the energy absorption capacity decreases under the punching force.Also,a more significant increase in ultimate loading with the loading velocity can be observed,compared with that of the energy absorption capacity.A qua-linear tensile constitutive model of fiber reinforced cementitious composite was constructed based on these experimental results,and the punching mechanic behavior of the fiber reinforced cementitious composite slab was simulated by the back-calculation model based on the plastic hinge method,and the material parameters of the fiber reinforced cementitious composite were obtained.This study can provide a solid base for the punch performance design of the PVA/cementitious composite slab.