CFRP板加固混凝土宽缺口试验梁界面滑移量求取方法

Calculation method for interface slip of wide-notch concrete beam strengthened with carbon fiber reinforced plastics plate

FRP板-混凝土之间界面的黏结能力可通过FRP-混凝土界面黏结滑移曲线来考量。为寻求相对准确的界面黏结滑移模型,研究外贴CFRP板加固混凝土梁界面特性,将混凝土梁的纯弯段混凝土保护层部分切除形成宽缺口梁,对混凝土梁实施外贴CFRP板加固,并对其进行四点弯曲加载,通过外置的测试系统可以精确测量CFRP板指定截面的移动量。试验和分析计算表明,用所设计的试验及其测试系统能够较准确地研究混凝土-CFRP板界面上的黏结剪应力及滑移特性,截面移动量易测,CFRP板受力明确且平均剪应力求取方便,可准确获取CFRP板与混凝土界面的滑移量及黏结滑移曲线,获取界面滑移量不需在CFRP板上密贴应变片,试验方法和界面滑移计算方法可为CFRP板与混凝土界面的特性研究提供参考。

Bonding capacity of the interface between FRP plate and concrete can be evaluated by FRP-concrete interface slippage curve. In order to find a relatively accurate interface bond-slip model, the interface performance of concrete beam strengthened with externally bonded CFRP plate was studied. Strengthened wide-notch concrete beam models were fabricated and tested, where the concrete cover at the pure bending section of models was partly removed to form the wide-notch on the side surface, externally bonded CFRP plates were used to strengthen the beams and the four-point bending test was accomplished. External measuring devices were mounted on the beam models to accurately measure the slippage of certain beam sections along the beam span. Results show that the test and its testing system are suitable to study the bonding shear stress and the slip properties at the interface of concrete and CFRP plate. The designated beam section movement is easy to measure. The stress distribution is clear and the average shear stress of CFRP plate is convenient to obtain. The slippage and bond-slip curve are accurate. Strain gauges are not necessary for the measurement of slippage. Thus the testing system and calculation method for slippage reported in this paper can provide help with other researches on the interface properties of CFRP and concrete.