基于智能筋的FRP筋与混凝土粘结滑移试验研究

发布时间：2018-05-12 05:24

本文选题：FRP筋 + 粘结滑移　；参考：《沈阳建筑大学》2014年硕士论文

【摘要】：在国内外建筑工程中,无论是施工阶段还是使用阶段,钢筋混凝土结构裂缝是常见的通病,结构裂缝导致的钢筋腐蚀问题更是日益突出,严重降低了结构的耐久性和安全性。为了解决该问题,人们提出了许多对策,其中采用纤维增强复合塑料(fiber reinforced polymer简称FRP)筋代替钢筋是解决该问题的有效途径。FRP筋与混凝土之间的粘结性能是决定FRP筋和混凝土共同工作,使两种材料充分地、正常地发挥作用的关键问题。此外,目前的大部分研究只着重于平均粘结应力随位移的变化规律,对于粘结长度范围内的粘结应力分布规律研究很少,因此如何准确测量内部的粘结机理是未来的发展方向。本文基于单端拉拔试验,制作了150mm×150mm×150mm的混凝土轴心受拉试块,进行了CFRP筋和GFRP筋的混凝土立方体试块单端轴心拉拔试验。并采用单端轴心拉拔试验方法,利用FBG-GFRP智能传感筋和外贴应变片智能GFRP筋,研究GFRP筋与混凝土之间粘结性能各基本变量沿埋长的变化特性,分析了智能GFRP筋与混凝土粘结界面的应力传递规律。试验结果表明：FRP筋与混凝土轴心拉拔试件的破坏形式包括加载端筋脆断破坏、筋拔出破坏和筋内部拉断破坏三种,其中筋拔出破坏分为肋剥离破坏和肋间混凝土劈裂破坏。根据试件典型的粘结滑移曲线走向,可将带肋FRP筋试件的粘结受力过程分为：微滑移阶段、滑移阶段、拔出阶段、下降阶段、残余波动阶段；光圆FRP筋试件的粘结受力过程分为：滑移阶段、下降阶段、水平阶段。普遍地,FRP筋与混凝土的粘结应力是由化学胶着力、机械咬合力和界面摩擦力组成的,针对带肋FRP筋试件和光圆FRP筋试件,分析了曲线各阶段的粘结机理,比较了CFRP筋试件和GFRP筋试件曲线的异同点,以及混凝土强度等级对粘结滑移曲线的影响。通过对试验数据拟合发现,三次曲线模型非常适合本试验粘结滑移曲线的上升段,改进的BPE模型的第二个公式非常适合本试验曲线的下降段,本文将两个模型组合起来得到了一种适合本试验数据的新模型。本文针对4种影响FRP筋和混凝土粘结强度的因素进行了分析,发现随着FRP筋直径的增大和粘结长度的增长,其粘结应力会减小；混凝土强度等级对FRP筋与混凝土的粘结应力影响很小,基本上随着混凝土强度等级的提高,粘结强度增加；加载速度越大,粘结应力越大。通过分析外贴片的智能FRP筋试验结果,得到了FRP筋应变应力随荷载和加载端滑移的变化规律,并得到了FRP筋与混凝土粘结应力在粘结长度上呈右偏态分布规律。通过比较应变传感器和电阻片所测结果,发现二者所得出的应变值随荷载和滑移的变化规律一致性很好,这说明了外贴应变片的试验具有很好的可靠性。通过本文的研究与分析,为FRP筋与混凝土的粘结滑移试验研究提供了一些借鉴,为深入、全面、系统地研究FRP筋的受力性能奠定了基础。
[Abstract]:In the domestic and foreign construction engineering, whether in the construction stage or the use stage, the reinforced concrete structure crack is the common malfunction, the reinforced bar corrosion problem caused by the structural crack is more and more prominent, which seriously reduces the durability and safety of the structure. In order to solve this problem, people put forward a lot of countermeasures, The effective way to solve this problem is to use fiber reinforced composite plastic fiber reinforced polymer instead of steel bar. The bond property between FRP reinforcement and concrete determines the joint work of FRP reinforcement and concrete, so that the two kinds of materials can be fully used. The key to functioning properly. In addition, most of the current studies only focus on the variation of average bond stress with displacement, and there are few studies on the distribution of bond stress in the range of bond length. Therefore, how to accurately measure the internal bond mechanism is the development direction in the future. Based on the single-end pull-out test, the concrete axial tensile test blocks of 150mm 脳 150mm 脳 150mm are made, and the single-end axial pull-out tests of the concrete cube specimens with CFRP bars and GFRP tendons are carried out. By using single-end axial drawing test method, using FBG-GFRP intelligent sensing bar and external strain gauge smart GFRP bar, the variation characteristics of the basic variables of bond performance between GFRP bar and concrete along the buried length are studied. The stress transfer law of the bond interface between intelligent GFRP bars and concrete is analyzed. The test results show that the failure forms of FRP tendons and concrete axial drawing specimens include brittle fracture of loading end tendons, pull-out failure of tendons and internal tensile failure of tendons, in which debonding of ribs and splitting failure of concrete between ribs. According to the typical curve of bond-slip curve, the bond stress process of ribbed FRP bars can be divided into three stages: micro-slip stage, pull-out stage, descending stage and residual fluctuation stage. The bond stress process of the smooth FRP bars can be divided into three stages: slip stage, descent stage and horizontal stage. Generally speaking, the bond stress between FRP bars and concrete is composed of chemical adhesive force, mechanical bite force and interface friction force. The bond mechanism of each stage of the curve is analyzed for the specimens with ribbed FRP tendons and smooth circular FRP tendons. The similarities and differences between the curves of CFRP and GFRP tendons and the influence of strength grade of concrete on the bond-slip curves are compared. By fitting the test data, it is found that the cubic curve model is very suitable for the rising section of the bond-slip curve in this experiment, and the second formula of the improved BPE model is very suitable for the descending section of the test curve. In this paper, the two models are combined to obtain a new model suitable for the experimental data. In this paper, four factors affecting the bond strength of FRP bars and concrete are analyzed. It is found that the bond stress decreases with the increase of the diameter and length of FRP bars. The strength grade of concrete has little effect on the bond stress between FRP bars and concrete, basically with the increase of concrete strength grade, the bond strength increases, and the greater the loading speed, the greater the bond stress. By analyzing the test results of intelligent FRP tendons with outer patches, the variation of strain stress of FRP tendons with load and loading end slip is obtained, and the distribution of bond stress between FRP tendons and concrete in the bond length is found to be right-skewed. By comparing the results of strain sensor and resistor gauge, it is found that the variation of strain value with load and slip is consistent with each other, which shows that the experiment of strain gauge sticking out has good reliability. Through the research and analysis in this paper, some references are provided for the experimental study of bond-slip between FRP tendons and concrete, which lays a foundation for the thorough, comprehensive and systematic study of the mechanical properties of FRP tendons.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU377.9

【相似文献】