预应力芳纶纤维布加固混凝土梁抗弯性能试验及理论分析

EXPERIMENT AND THEORETICAL RESEARCH ON FLEXURAL PERFORMANCE OF RC BEAMS STRENGTHENED WITH PRESTRESSED AFRP SHEETS

预应力技术是充分发挥FRP复合材料高强性能的一条有效途径。通过对预应力芳纶纤维布加固混凝土梁抗弯的试验,对预应力水平对梁抗弯承载力、刚度、延性的影响进行分析。结果表明：预应力水平为55%～65%时,预应力芳纶纤维布加固梁的开裂、屈服、极限荷载比非预应力芳纶纤维布加固梁分别提高约147%～165%、28%～50%、13%～31%,表明预应力芳纶纤维布能显著地提高混凝土梁的抗弯性能。承载力极限状态时,预应力梁为纤维布的断裂破坏,非预应力梁发生布与混凝土间局部脱粘破坏。在试验研究的基础上,采用弹塑性截面分析法计算梁的承载力,理论计算值与试验值吻合良好。

Prestress technology is an effective way to use the high strength of FRP composite.The experimental study on flexural performance of strengthening RC beams using prestressed aramid fiber reinforced plastic（AFRP） sheets is conducted,and the effects of different prestress level on the properties of flexural load,stiffness and ductility are analyzed.Results show that,when prestress level is 55%～65%,the cracking load,yield load and ultimate load of RC beams strengthened with prestressed AFRP sheets are 147%～165%,28%～50%,13%～31% larger than that of RC beams strengthened with non-prestressed AFRP sheets,validating the effectiveness of prestressed AFRP sheet retrofit.The failure pattern of prestressed AFRP sheets is fracture,but that of non-prestressed AFRP sheets is debonding.Based on the experimental study,an elastoplastic section analysis method is conducted to predict the loads of beams,the results from the theoretical predictions and the experiment agree well.