体外预应力FRP筋混凝土梁受力性能的试验研究

Experimental study on mechanical behavior of external prestressed FRP reinforced concrete beams

为了研究体外预应力复合材料筋混凝土梁的破坏特征和承载性能,对12根全FRP筋试验梁开展了三分点加载试验,其中体外预应力筋为碳纤维增强复合材料(CFRP)筋,受力筋和箍筋采用玻璃纤维增强复合材料(GFRP)筋。对比分析预应力水平、剪跨比、混凝土种类等因素变化对GFRP筋混凝土梁承载力的影响,推导了包含预应力筋应力增量影响的受弯承载力表达式,并将计算结果与试验结果进行对比。结果表明,无预应力梁的破坏主要由变形控制,施加预应力梁的破坏由变形控制转变为承载力控制。预应力FRP筋混凝土梁跨中挠度与预应力增量基本呈正比例关系。FRP筋梁承载力随剪跨比的增大而减小,且剪跨比对开裂荷载的影响更显著。混凝土种类对预应力梁开裂荷载的影响大,而对无预应力梁的开裂荷载和极限荷载影响较小。本文推导的预应力FRP筋混凝土梁承载力计算结果与实测值吻合较好。

This study proposes to investigate the failure characteristics and load-bearing performance of external prestressed composite reinforced concrete beams by conducting a three-point loading test on 12 full FRP reinforced concrete beams.These external prestressed concrete beams were reinforced with car-bon fiber reinforced polymer(CFRP),while the stress reinforcement and stirrup were made of glass fiber reinforced polymer(GFRP).Specifically,the study compares the impact of prestress level,shear span ratio,and concrete type on the bearing capacity of GFRP reinforced concrete beams.derives an ex-pression for flexural bearing capacity to account for the effect of stress increment of prestressed tendons,and is verified by experimental results.The test results indicate that the failure of non-prestressed FRP reinforced concrete beams is primarily governed by deformation,whereas applying prestress can shift the failure mode from deformation control to bearing capacity control.The mid-span deflection of the con-crete beam is directly proportional to the increase in prestress.The bearing capacity of FRP beams de-creases with an increase in shear span ratio,with particularly significant effect on cracking load.The effect of concrete type on the cracking load of prestressed beams surpasses its impact on the ultimate load,while it exerts minimal influence on cracking and ultimate load of non-prestressed beams.The cal-culated results for the bearing capacity of prestressed FRP reinforced concrete beams derived in this study align well with the measured values.