FRP约束混凝土圆柱无软化段时的应力-应变关系研究

在国内外大量试验研究的基础上,比较分析了FRP、箍筋及钢管约束混凝土圆柱性能的差异。指出FRP约束混凝土圆柱的极限强度主要与FRP侧向约束强度、未约束混凝土强度及FRP形式等有关,并提出FRP约束圆柱后极限强度计算方法。指出已有的FRP约束混凝土圆柱极限应变计算方法误差均较大,本文提出新的极限应变计算方法:首先,发现FRP约束混凝土圆柱的极限泊松比趋向一恒定值,并建议了极限泊松比的计算公式,然后根据应变相容可确定FRP约束混凝土圆柱的极限应变。最后,建议了确定FRP约束混凝土圆柱无软化段时应力-应变关系的三折线模型,与已有的试验结果比较表明,模型简单且精度高,能适用于AFRP、GFRP、CFRP等不同类型及FRP管和FRP布等不同形式FRP约束的混凝土圆柱。

Study on the stress-strain relation ship of FRP-confined concrete circular column without a strain-softening response

Based on a large number of test data,t he performances of concrete circula r columns confined with fiber reinforced polymer /plastic(FRP),steel tube and steel stirrup have been compared.The ultimate strength o f FRP-confined concrete is mainly related to FRP confinement strength,th e strength of unconfined concrete an d the form of FRP.Equations for predicting the ultimate strength are suggested.It is pointed out that the existing models for the ultimate strain of FRP-confined con crete circular columns were not satisfied.Thus,an innovative method is proposed.First,it is found that the ultimate P oisson's ratio of FRP-confined concrete trends toward a constant value,and a cal-culation method is suggested.And th en,according to strain compatibility,the ultimate strain of FRP-confined concrete can be easily predicted.Finally,a s imple tri-linear model is presented to predict the stress-strain respon se of FRP-confined concrete circular columns.Through comparing with a lot of experimental data,the effectiveness of the proposed model is confirmed.The mod el can be applied to the concrete circ ular columns confined with various t ypes of FRPs,such as AFRP,GFRP,CFRP,and th e form of FRP can be either sheet or tube.