Vibration And Stress Intensity Factor Analysis Of RC Beams Reinforced Using CFRP With Cracks

Reinforced concrete beams are widely used in Bridges,underground engineering,buildings and other structures because of their high strength,strong durability,mouldadibility and good integrity.Reinforced concrete beam as the typical inhomogeneous nonlinear material,itself has certain initial defects such as micro cracks easily,when the stack in the process of engineering changes in the environment and the construction technology is not standard,so,there must be cracks in reinforced concrete beam structure in service of the occurrence,development,and led to the decrease of the beam structure bearing capacity and reduce the service life and even cause the destruction of the structure.Therefore,It is a more economic and social benefit method to properly strengthen and reinforce it for the concrete beam structure with cracks,which can improve concrete beam structure mechanical performance and the bearing capacity and durability of the bridge structure with cracks.With the continuous progress of composite material technology,FRP has attracted the attention of engineers and scholars because of its characteristics such as light weight,high strength,corrosion resistance and fatigue resistance.At the same time,with the decline of the price of FRP,FRP is widely used in the reinforcement of all kinds of engineering structures to improve the bearing capacity and service life of the structure.The dynamic characteristics and fracture behavior of RC beams with cracks have been changed to some degree after the reinforcement with FRP.Therefore,the dynamic analysis and fracture analysis of RC beams reinforced with CFRP with cracks are helpful for people to understand the dynamic and fracture properties of reinforced beams,which can provide a theoretical basis for bridge reinforcement design.In the chapter 2,based on Euler-Bernoulli beams,the dynamic governing equations of RC beams reinforced with cracks are established by using Hamilton’s principle,in which the confinement effect of steel bars and CFRP and the stress concentration effect are considered in the cracked area.In the chapter 3,the governing equation is solved by using the Galerkin method.Studying the effects of crack number,crack depth and crack spacing on the natural frequency of the reinforced beam.In the chapter 4,analyzing the governing equation under harmonic load by using Newmark-β method,studying the influence of crack number,crack depth and crack location on the dynamic performance of the reinforced beam.In the chapter 5,An equation was given to calculate the stress intensity factor（SIF）of the mode I crack in the RC beam strengthen with cracks,on the basis of considering reinforcement beam neutral axis changes,combined with the three preceding chapters.Combined with the above get the displacement response of values,Calculating the mode I stress intensity factor of the RC beam strengthen,and analyzing the influence of cracks depth,load size,the number of cracks for mode I stress intensity factor.the whole research content is summarized and analyzed,and the factors neglected in the research are considered,and the dynamic analysis and fracture analysis of RC beams reinforced with cracks CFRP are prospected,which provides some ideas for the future research direction.