带锚固端BFRP筋-混凝土的粘结性能试验与本构模型研究

BOND-SLIP TEST AND CONSTITUTIVE MODEL BETWEEN BFRP BAR WITH ANCHORAGE AND CONCRETE

BFRP筋是一种可取代钢筋用于海洋工程的新型增强材料,具有广阔的应用前景。针对BFRP筋在混凝土结构中粘结强度不足的问题,采用碳纤维布锚固的方法改善BFRP筋-混凝土粘结性能,从而提高BFRP筋与混凝土的协同作用。该文通过20个中心拉拔试件,分析了碳纤维锚固长度、锚固直径及混凝土强度对试件粘结-滑移性能和破坏形态的影响。结合试验结果对现有模型的粘结特征参数进行修正,提出碳纤维布锚固条件下BFRP筋-混凝土的粘结强度计算公式,建立一种BFRP筋-混凝土粘结滑移本构模型。结果表明:碳纤维锚固端可以有效的提高粘结性能,限制混凝土开裂,提高残余粘结强度,充分发挥BFRP筋的增强作用;混凝土强度是影响锚固性能的主要因素;随着锚固长径比的提高,碳纤维的锚固性能逐渐提升。

Basalt Fiber Reinforced Polymer(BFRP)is a new reinforcing material alternative to steel bar in marine engineering,and exhibits good application prospects.Carbon fiber mat anchorage is employed to improve the bond performance between BFRP bars and concrete due to the insufficient bond strength at the interface of BFRP bar-to-concrete,which helps to increase the reinforcing effect of BFRP bar.In this paper,pull-out tests on 20 specimens are carried out,and the influences of carbon fiber anchorage length,anchorage diameter and concrete strength on bond-slip behaviors and failure patterns are investigated.The bond characteristic parameters presented in existing theoretical models are modified based on the experimental data obtained in the paper.The calculation formula of bond strength at the interface of BFRP bar with anchorage end-to-concrete is obtained and a constitutive model is further given.Results indicate that the bond performance between BFRP bar and concrete can be greatly improved by the carbon fiber mat anchorage.The crack propagation of concrete can be effectively prevented and the residual bond strength is also enhanced,and thus the reinforcing effects of BFRP bar can be fully developed.The strength of concrete is the main factor affecting the anchorage performance,and the anchorage performance of carbon fiber mat is enhanced with the increase of anchorage length-to-diameter ratio.