Low Height Concrete Beam Reinforcement Method Research

Low height concrete beam bridge occupies the certain proportion in our country’srailway and highway system. With the increasing road load, the problem of low height beamstiffness and insufficient bearing capacity are more and more prominent and seriously affectthe traffic safety. Taking low height concrete beam bridge in hejiu railway line as thebackground, in view of the low height beam stiffness and bearing capacity togetherinsufficient and its strict clearance limit under the bridge, the text has carried on the followingresearch work：1. Through the analysis of various bridge reinforcement methods’ advantages anddisadvantages, puting forward two kinds of low height beam reinforcement methods: theanchor sticking steel plate reinforcement and prestressed carbon fiber reinforcement method.2. According to the characteristics of low height beam, deducing the anchor stickingsteel plate reinforcement beam and prestressed carbon fiber reinforcement beam’s bearingcapacity, stiffness and deflection formulas, and discussing the reinforcement beam’s failuremode.3. Etablishing the anchor stick steel plate reinforcement beam finite element models withdifferent anchor sticking steel plate section distribution ratios and the prestressed carbon fiberreinforced beam finite element models with different section distribution ratios of prestressedcarbon fiber cloth, comparing and analyzing the reinforcement beam mid-span maximumdeflection and bending section concrete crack range, founding that the anchor sticking steelplate method can significantly reduce the low height concrete beam mid-span maximumdeflection values, control the development of crack, the stiffness increasing rate isproportional to anchor steel plate section distribution ratio,while when the section distributionrate is more than0.045%(six layers of carbon fiber cloth), the beams strengthened withprestressed carbon fiber cloth has significant effect in improving the low height beamstiffness aspect. To stiffness increasing, the anchor sticking steel plate reinforcement methodis better than the prestressed carbon fiber reinforcement method.4. By comparing and analyzing the bearing capacity of the anchor sticking steel platereinforcement beams with different anchor steel plate section distribution ratios and theprestressed carbon fiber reinforcement beams with different section distribution ratios ofprestressed carbon fiber cloth, founding that the anchor sticking steel plate method cansignificantly increase the low hight beam’s cracking load, yield load and ultimate load. Whenthe reinforcement beam’s failure mode is reinforced damage, the bearing capacity increasingrate is proportional to anchor steel plate section distribution ratio, while the beamsstrengthened with prestressed carbon fiber cloth has unconspicuous effect in improving the low height beam’s cracking load, yield load and ultimate load. To bearing capacity increasing,the anchor sticking steel plate reinforcement method is better than the prestressed carbon fiberreinforcement method.5. Through the analysis of the anchor sticking steel plate reinforcement beam andprestressed carbon fiber reinforcement beam’s load-strain curve, it can be known that in thepreliminary loading stage, two reinforcement methods can delay the low height beamconcrete strain, improve the beam elastic stress range.6. Through the analysis of the anchor sticking steel plate reinforcement beam andprestressed carbon fiber reinforcement beam’s failure mode, it can be known that when theanchor steel plate section distribution ratio is less than1.66%and the section distribution ratioof prestressed carbon fiber cloth is less than0.045%, the anchor sticking steel reinforcementbeam and prestressed carbon fiber reinforcement beam’s failure mode is reinforced damage.