L形FRP粘贴法加固混凝土框架梁负弯矩区试验研究

Experimental study on strengthening of negative moment region of RC frame beams by L-shaped FRP bonding method

提出了一种混凝土框架梁负弯矩区受弯性能加固的L形FRP片材粘贴加固法,该方法利用角钢实现FRP在梁柱阴角处的转向锚固.通过6个足尺框架梁柱边节点试件的单向静力加载和低周反复加载试验,对比了利用L形FRP粘贴加固法和规范建议FRP粘贴加固法加固后梁的破坏形态、受弯承载力、刚度、延性、耗能能力等性能指标.试验结果表明,粘贴L形FRP片材加固后,梁根部FRP与试件相应位置截面在加载过程中变形协调,应变关系基本符合平截面假定.低周反复荷载作用下,梁受弯承载力和刚度的提高幅度与静力荷载作用下几乎相同,表明L形FRP粘贴加固法中的锚固装置完全限制了阴角处FRP片材从被加固体基面上法向剥离的位移趋势,使得加固效果更加稳定.

The L-shaped fiber reinforced polymer （FRP） bonding method for enhancing the flexural performance of negative moment region of RC beams is proposed, in which angle steel is settled to anchor FRP sheet at the frame joint. Six full scale frame joint specimens were tested under static load or low frequency cyclic load. Then, the failure mode, flexural capacity, stiffness, ductility and energy dissipation ability were compared between the RC beams strengthened by the proposed L-shaped FRP bonding method and those strengthened by the recommended method in current specification. The experimental results show that by the L-shaped FRP bonding method, deformation coordination between the FRP at the beam root and the corresponding section of the frame beam are achieved in the process of loading, and thus the stress-strain relationship basically agrees with the plane crosssection assumption. Under low frequency cyclic load, the increase of flexural capacity and stiffness of the beam are almost the same as those under the action of static loads. The trend of FRP debonding vertically from the surface of concrete can be completely restricted by the anchor device and thus more stable strengthening effect is achieved.