Research On Parameters Of CFRP Enclosed Reinforced Concrete Cylinder Subjected To Low Velocity Impact

Reinforced concrete structures may suffer low-speed impacts that are negligible in conventional design codes during daily use.At this time,the externally-bonded carbon fiber reinforced composite material(CFRP)used to reinforce the reinforced concrete structural members may undergo serious deformation And damage,which leads to the reduction or even loss of reinforcement of structural members.In the existing research,there is still a lack of a systematic and quantitative understanding of this potential safety hazard.At the same time,the current external CFRP reinforced concrete structure design method mainly reflects the advantages of CFRP in strength and ease of construction,but less involved in the anisotropy and brittle fracture characteristics of CFRP.Reinforced concrete structural members reinforced with CFRP have a certain degree of brittleness,which also causes hidden dangers in daily life.Therefore,this paper takes this as the research focus,and establishes an explicit finite element analysis model of the CFRP hoop beam-reinforced RC column subjected to low-speed impact and the implicit damage under static load of the impact damage column The finite element analysis model systematically studied the impact of different factors on the impact resistance of RC columns strengthened by CFRP hoop beams and the residual bearing capacity of damaged RC columns.The main research contents of this thesis are as follows:First,the impact test and axial compression test of CFRP reinforced columns were completed using the test device of this research group,and the explicit and implicit under the same working conditions were established using the finite element analysis software ANSYS/LS-DYNA Finite element model.Through comparison,it is found that the contact force time history curve of the specimen during the impact process of the finite element simulation,the failure range of the specimen and the load-displacement curve of the axial compression process are in good agreement with the test results,which verifies the correctness of the finite element analysis method in this paper.Subsequently,a more systematic simulation of the dynamic response of the CFRP-reinforced RC column under impact was completed,and the mechanics of thecontact force time history curve,energy time history curve,stress distribution of each part,and the destruction process of the test specimen were studied and analyzed.The characteristics and comparative analysis of the impact of the initial velocity of the hammer,the thickness of the CFRP reinforcement,the shape of the hammer,the quality of the hammer and the concrete strength level on the impact resistance of the CFRP reinforced RC column.The results show that the initial velocity of the hammer is the most direct factor that affects the dynamic response and damage of the CFRP reinforced column under low-speed impact;the reinforced thickness of the CFRP specimen,the shape of the hammer,the quality of the hammer,and the concrete strength level of the specimen It is an important factor that affects the dynamic response and damage of CFRP reinforced columns under low-speed impact.Finally,using the explicit-implicit continuous solution method,the implicit finite element software ANSYS was selected to complete a more systematic simulation of the axial compression process of the CFRP reinforced RC column after impact damage,and the load-displacement curve and cracks of the specimen were studied and analyzed.The development process and stress-strain distribution and other finite element results were analyzed.The effects of initial velocity of the hammer,thickness of CFRP reinforcement,shape of the hammer,weight of the hammer,and concrete strength level on the residual bearing capacity of the CFRP reinforced RC column after impact damage were analyzed.The results show that when the test piece is subjected to a negligible low-speed impact in conventional design codes,its residual bearing capacity decreases significantly.The initial velocity of the hammer,the thickness of the CFRP reinforcement,the shape of the hammer,the quality of the hammer,and the concrete strength grade are all important factors that affect the mechanical properties of the CFRP reinforced damaged column.