CFRP加固RC梁的抗疲劳与防腐蚀效用

CFRP FATIGUE RETROFITTING AND PROTECTION EFFECTS FOR CORRODED REINFORCED CONCRETE BEAMS

总结分析了腐蚀混凝土梁用FRP片材加固后的疲劳特性。共10根梁试件,其中1个梁未加固未腐蚀作为标准梁;3个梁进行腐蚀但未加固;3个腐蚀梁用GFRP布U型加固;3个梁受拉区用CFRP布进行抗弯加固,同时用GFRP布U型固定。当纵筋腐蚀到5.5%后,用FRP加固。FRP加固后,一些梁立即进行疲劳试验使其破坏,一些梁再进行第二次腐蚀以研究CFRP加固对梁抗腐蚀耐久性的影响。腐蚀坑使钢筋疲劳寿命明显下降。用U型FRP包裹RC梁不能明显改善梁的疲劳性能;但用CFRP加固梁受拉区,可显著提高梁的疲劳性能。预应力加固降低了梁中纵筋应力幅,疲劳寿命随预应力水平的增大而提高,预应力加固使梁的疲劳寿命明显提高。

The experimental results of the structural fatigue performance of corroded reinforced concrete （ RC ） beams repaired with fiber-reinforced polymer （FRP） sheets were summarized in this paper. Ten RC beam specimens （152 × 254 ×3,200mm） were constructed. One was neither strengthened nor corroded to serve as a reference; three were corroded but not repaired; another three were corroded but repaired with U-shaped glass FRP sheets that wrapped the cross section of the specimen; and the remaining three were corroded and repaired with U- shaped glass FRP sheets for wrapping and carbon-fiber-reinforced polymer （CFRP） sheets for flexural strengthening. The FRP sheets were applied after the main reinforcing bars were corroded to an average mass loss of 5.5 %. Following FRP repair, some specimens were tested immediately to failure while the other repaired specimens were subjected to further corrosion before being tested to failure to investigate their long-term protecting performance. Reinforcement steel pitting due to corrosion reduced the fatigue life significantly. The FRP wrapping had no significant effect on the fatigue performance, while using CFRP sheets for flexural strengthening enhanced the fatigue performance significantly. The fatigue life of the retrofitting RC beams was increased with the decrease of the reinforcements stress amplitude.