四种FRP管约束UHPC轴压特性的试验研究

为研究纤维增强聚合物(fiber reinforced polymer,FRP)管约束超高性能混凝土(ultra-high performance concrete,UHPC)的轴压特性,分别对4个未约束和36个约束圆柱体试件进行了轴压试验,测定了应力-应变全曲线,获得了强度和极限应变值.试验结果发现:FRP约束UHPC可明显提高其强度和变形能力,纤维布层数愈多、强度越高,改善效果愈明显;轴压应力-应变曲线为双线性;在相近的约束比下,FRP管约束刚度越小,约束试件的极限应变值越大;已有的强度和极限应变的模型预测值均高于实测值,极限应变预测值偏离试验值更大.本文回归得到了FRP管UHPC的强度和极限应变预测公式预测精度较高.

Compressive Behavior of Four Types FRP Tube Confined Ultra-high-performance Concrete

An axial compression test was conducted to investigate the performance of ultra-high performance concrete ( UHPC) specimens confined with different types and thickness of fiber reinforced polymer ( FRP) tubes. 40 cylindrical specimens were prepared, of which 4 were non-confined while the rest were confined with FRP tubes. Stress-strain curves were produced, and the strength and ultimate strains obtained. The test results show significant enhancement in ultimate strength and strain of UHPC. The confinement effectiveness improves with increase in the FRP layers, and also with increase in strength of FRP. Axial compression stress-strain curves relationship exhibits bilinear characteristics. Under the same confinement ratio, the smaller the stiffness of FRP tube is, the greater the ultimate strain value of the confined specimen becomes. The predicted value of both ultimate strength and strain of existing models is higher than the tested value, and the predicted values of the ultimate strain are more higher than that of the experimental results. The accuracy of the formula for the prediction of strength and ultimate strain of FRP tube confined UHPC specimens suggested in this paper is higher.