摘要
纤维增强树脂复合材料(Fiber-reinforced polymer,FRP)筋的粘结性能是影响FRP筋混凝土构件力学性能的关键性因素,而目前有关带肋FRP筋表面处理工艺、几何特征等因素对粘结性能影响的研究还不足,当前主要设计规范也缺乏此方面的规定。本文以螺旋缠绕挤压肋FRP筋(简称螺旋肋FRP筋)为研究对象,通过搜集大量粘结性能试验数据,分析各主要研究变量对粘结损伤模式和粘结强度的影响规律,重点关注筋表面几何特征造成的影响,明确了螺旋肋FRP筋的粘结机制。结果表明,增大混凝土强度使粘结破坏的薄弱区域逐渐从筋与混凝土间咬合层的界面1(混凝土损伤为主)转移到界面2(纤维树脂损伤为主),同时粘结强度也增大,并且混凝土肋宽比C_(LR)越大,增加混凝土强度对粘结强度的提升越明显;增大相对肋高hrd和混凝土肋宽比C_(LR)导致筋与混凝土间咬合层的损伤程度加大,二者的机械咬合作用增强,粘结强度也相应增加;采用多元非线性回归的方式提出了适用于螺旋肋FRP筋的粘结强度计算公式,其预测结果与试验吻合较好,预测精度远高于目前的主流设计规范,究其根本原因在于本文所提公式准确考虑了FRP筋表面几何特征对粘结强度的影响规律。
The bond behavior of fiber-reinforced polymer(FRP)bars is a critical factor in the mechanical performance of FRP rebar reinforced concrete structures,but until now,there has been limited research on the effect of surface treatment and geometrical features of ribbed FRP bars on the bond behavior,and no relevant provisions are incorporated into the current main design codes.In this paper,the helically and tightly wound FRP bar was taken into consideration,and large amount of existing test data were also collected to investigate the main test parameters on the bond failure modes and bond strength.Greater emphasis was placed on the effect of geometrical features of such FRP bars on bond behavior,and the bond mechanism was clarified.Results show that with the increase of concrete strength,the weak bond damage area in the bar-concrete interlocking layer transfers gradually from interface 1(main damage in concrete)to the interface 2(main damage in resin fiber),and the bond strength increases accordingly.Meanwhile,the larger the concrete lug ratio C_(LR),the greater the increase of bond strength due to the increase of concrete strength.With the increase of relative rib height h_(rd) and C_(LR),the bond damage in the bar-concrete interlocking layer becomes severer,contributing to stronger mechanical interlocking and higher bond strength.Multivariate nonlinear regression was adopted to propose a formula to estimate the bond strength of the helically and tightly wound FRP bars.The calculated results by the proposed equation are in good agreement with the test results with greater accuracy than the current design codes.This is because the effect of surface geometrical features on bond strength is accurately accounted in the proposed equation.
作者
董恒磊
李东风
王代玉
DONG Henglei;LI Dongfeng;WANG Daiyu(School of Science,Harbin Institute of Technology,Shenzhen 518055,China;Bureau of Public Works of Longgang District of Shenzhen Municipality,Shenzhen 518172,China;School of Civil Engineering,Harbin Institute of Technology,Harbin 150090,China)
出处
《复合材料学报》
EI
CAS
CSCD
北大核心
2022年第11期5239-5250,共12页
Acta Materiae Compositae Sinica
基金
国家自然科学基金面上项目(51878224)。
关键词
螺旋肋FRP筋
表面处理工艺
几何特征
粘结破坏模式
粘结强度
理论计算公式
helically wound FRP bars
surface treatment
geometrical features
bond failure
bond strength
theoretical calculation equation
