基于缩尺模型的玄武岩纤维布加固桥梁抗弯性能试验

Experimen on Flexural Behavior of Bridge Structure Strengthened with BFRP Sheet Based on Scale Model

以一座主跨径为20 m的5孔钢筋混凝土简支梁桥为实例,基于相似理论按照几何尺寸比CL=1/4设计了T形主梁的9片缩尺模型梁,试验共分为3组,探讨了不考虑二次受力情况(试验2)与考虑二次受力情况(试验3)下对梁体进行贴BFRP布加固后构件的极限承载力、裂缝开展、BFRP布应变及最终的破坏模式等相关力学特性,并与未加固对比梁(试验1)的力学性能指标进行了对比分析。结果表明,试验2、3中的平均挠度值较试验1分别降低了36.7%及28.9%;并且试验2、3中梁破坏时BFRP布平均应变值分别为15 118、10 921με分别是BFRP布极限拉应变17 916με的84.4%和61.0%,说明BFRP布加固后对梁体的刚度有显著的提高且试验2加固效果要优于试验3;所有加固梁的最终破坏模式均表现为脆性破坏。通过理论计算值与试验结果对比可知,BFRP加固T形混凝土结构设计中,可按我国现行混凝土结构加固设计规范进行设计计算。

Taken a reinforced concrete beam bridge which has 20 m main span as an example,based on similarity theory,9 scale model beams of T-beam were designed in accordance with CL=1/4.The test was divided into three groups： test I： contrast beams without reinforcement,test II： reinforced beams without considering the secondary load,and test III： reinforced beams considering the secondary load.The ultimate load,crack propagation,strain of basalt fiber reinforced polymer（BFRP） sheet and the ultimate failure mode of the beams strengthened by BFRP sheet in the cases of test II and test III discussed.By comparing the results of three tests,it shows that（1） the average deflections of test II and test III decreased by 36.7% and 28.9% respectively than that of test I;（2） the final average strains of BFRP sheet in test II and test III are 15 118 με and 10 921 με which are 84.4% and 61.0% of the ultimate tensile strain of BFRP sheet respectively,indicating the stiffness of beams is increased after reinforced by BFRP sheet and the reinforcement effect of test II is better than that of test III;（3） all the ultimate failure mode of reinforced beams are brittle failure.Compared with the experiment results and calculated values,it can be seen that the reinforced concrete T-type structure strengthened with BFRP sheet can be designed according to Design Code for Strengthening Concrete Structure.