TRC加固RC梁的弯曲疲劳破坏过程和应变发展的试验研究

EXPERIMENTAL STUDY ON BENDING FATIGUE DAMAGE AND STRAIN DEVELOPMENT OF RC BEAM STRENGTHENED WITH TRC

  • 摘要: 该文采用四点弯曲加载方式研究了加固方式、配网率、配筋率、损伤程度等对TRC加固RC梁疲劳寿命、破坏过程及应变发展的影响。试验结果发现:TRC加固梁在疲劳荷载作用下其破坏过程可以分为三个阶段。第一阶段:循环次数大约在4万次以内,新的裂缝会不断产生,此阶段末裂缝基本出齐,该阶段相对加固梁的整个寿命过程较短;第二阶段表现为加固梁的挠度几乎不变,该阶段末梁会产生新的裂缝,并形成主裂缝;第三阶段:加固梁的跨中挠度迅速增加,在时间很短的情况下梁发生疲劳破坏。加固梁的混凝土压应变与受拉钢筋应变随荷载循环次数的增加也呈三个阶段发展:初始发展、稳定发展和迅速发展。配网率和配筋率的增大都会减缓中和轴的上移速度,减小疲劳破坏时梁顶混凝土压应变,从而提高疲劳寿命。较大荷载作用下的静力损伤会使加固梁的钢筋应变提前进入第三阶段的发展,会减小RC梁的疲劳寿命。

     

    Abstract: Four-point bending loading test was carried out to study the influence of reinforcement forms, reinforcement ratios of TRC and steel bars, and damage degree of beams on fatigue life, destructive process and strain development of beams reinforced with TRC. The results show that the destructive process of reinforced beams can be divided into three stages. At the first stage,at approximately 40000 cycles, new cracks appear,and at the end of this stage no new cracks shows up, this stage is short compared with the whole process. At the second stage, the deflection of beams has almost no increment, and at the end of this stage, more new cracks appear and the main crack forms. At the third stage, the mid-span deflection of beams rapidly increases, and the fatigue failure occurs in a short time. The compressive strain of concrete and the tensile strain of steel bars also have three development stages: beginning development stage, stable development stage, and rapid development stage. The increase of reinforcement ratios of TRC and steel bars can improve the fatigue life of beams through slowing down the rising speed of neutral axis and reducing the concrete compression strain of fatigue failure. The larger damage induced by static load results in the earlier arrival of the third stage of the reinforced beam and reduces the fatigue life of reinforced beams.

     

/

返回文章
返回