BFRP层数对加固钢筋混凝土梁抗弯性能的影响

The influence of BFRP layers on the bending properties of the reinforced concrete beams

为了研究不同层数玄武岩纤维布(basalt fiber reinforced polymer,BFRP)对加固钢筋混凝土梁抗弯性能的影响,使用分离式油压千斤顶对梁进行三分点加载试验。分别观测梁底部粘贴1层、2层和3层BFRP时加固梁的破坏形态、开裂荷载、屈服荷载、极限荷载及以上荷载对应的跨中挠度,并与基准梁进行了对比分析。试验结果表明:随着BFRP粘贴层数的增加,梁的破坏形态发生了改变,主裂缝数量减少,开裂荷载、屈服荷载和极限荷载均有不同程度的提高,其中极限荷载分别提高了7.92%(1层)、23.66%(2层)和29.31%(3层),对应跨中挠度也分别降低了14.54%、26.65%和28.81%;粘贴1~2层BFRP时,梁的延性系数有所增大,而粘贴3层BFRP时,延性系数减小;弯曲裂缝的产生和扩展是引起BFRP发生破坏的主要原因;梁的抗弯性能并不与BFRP层数成比例增加,综合来看,采用2层BFRP加固的梁,不仅抗弯承载力和延性得到了较大提高,跨中挠度也大幅下降,具有良好的经济性。

In order to study the impact of different layers of basalt fiber reinforced polymer（ BFRP） on the bending performance of reinforced concrete beams,three dividing point loading experiments were performed on the beams with a separate hydraulic jack. The failure modes,crack loads,yield loads,ultimate loads and the mid-span deflections corresponds to the above loads of the beams reinforced with 1,2 and 3 layers of BFRP at the bottom of the beam were observed respectively and compared with the reference beam. The experiment results showed that,with the increasing number of the pasted BFRP layers,failure modes of the beams were changed,the number of primary cracks were decreased,crack loads,yield loads and ultimate loads were increased with varying degrees. The ultimate loads were respectively increased by 7. 92%（ 1 layer）,23. 66%（ 2 layers） and 29. 31%（ 3 layers）,and corresponding span deflections were also respectively decreased by 14. 54%,26. 65% and 28. 81%. When 1 ~ 2 layers of the BFRP were pasted,ductility factors of the beams were increased and the ductility factor was reduced when 3 layers of BFRP were pasted.The generation and expansion of the bending cracks were the main cause of the failure of BFRP. The flexural behavior of the beams was not proportional to the increase of the number of the BFRP layers. Taking together beams strengthened by 2 layers of BFRP,not only the bending bearing capacity and ductility have been greatly improved,but also the deflection has been greatly reduced which has good economic performance.