Study On Fracture Mechanical Property Of Bonding Interface In GFRP Plate-Asphalt

As a new type of bridge deck pavement system,the FRP plate-asphalt mixture system has the typical characteristics of bonding materials,and the performance of bonding interface has a decisive impact on the strength and service life of bridge deck pavement structure.The stress intensity factor?SIF?theory of fracture mechanics of homogeneous materials is not suitable for calculating the SIF of FRP plate-asphalt mixture.Based on the linear elastic interface fracture mechanics theory,the GFRP plate-asphalt mixture bonded interface is obtained of the stress intensity factor and the numerical method,adopt the method of combining theoretical analysis and experimental study,the interface stress intensity factor as evaluation index,reveals the GFRP sheets-of prefabricated crack in asphalt mixture bonding interface fracture failure mechanism,established the corresponding bonding interface strength criterion,the GFRP plate-asphalt mixture composite beam fatigue life of asphalt mixture parameter influences of experimental research.The research content includes the following aspects:?1?Numerical calculation of interface stress intensity factorThere exist both 1 r stress singularity and?stress oscillation singularity near the interface crack tip of GFRP plate-Asphalt,and singular element and SIF of isotropic material in fracture mechanics can not be directly used to evaluate the strength near the interfacial crack tip field.Taking the opening displacement of the interfacial crack and the stress at the crack tip as the basic quantities,the interface SIF of orthotropic materials is studied,and the numerical calculation method of the interfacial stress intensity factor of the orthogonal anisotropic material and the orthogonal anisotropic material is obtained on the basis of the interfacial stress intensity factor of the orthogonal anisotropic material and the bimaterial interfacial stress intensity factor of the orthogonal anisotropic material.?2?Parameter analysis of GFRP plate-asphalt Brazilian Disk specimensAs an evaluation parameter of the interface strength of GFRP plate-asphalt,the interface SIF is obtained on the basis of the finite element numerical calculation and experimental study of the Brazilian Disk specimens,so it is important to ensure the rationality and feasibility of the finite element numerical calculation method and the test program.On the basis of finite element simulation of Brazilian Disk specimens of GFRP plate and asphalt,the effects of crack tip element type and element size on crack tip stress field,displacement field and interface SIF are discussed.A reasonable finite element simulation method is established.The effects of specimen radius and crack width on the interface SIF are discussed.By dimensionless treatment of the interface SIF,the suitable structural size of the Brazilian Disk specimen is obtained,which lays a foundation for finite element simulation and experimental study of Brazilian Disk interface strength evaluation.?3?Interface mechanical properties analysis of GFRP plate-asphalt under tension and shear stress stateTaking Brazilian Disk specimens with central precast interface crack as the research object,the failure tests of 81 specimens under tension and shear stress state of GFRP plate-asphalt interface mechanical properties are carried out,which tests are in 9 working conditions and the loading angles of the specimens are in the range of 25 degree to 90 degree.The finite element simulation calculation and analysis of the test are carried out,and the critical SIF of the bi-material interface of GFRP plate-asphalt is calculated according to the test datum,and the experimental phenomena are analyzed,and the failure mechanisms are revealed.The elliptical criterion of interface bonding strength between GFRP plate-asphalt is established under tension and shear stress state.?4?Interface mechanical properties analysis of GFRP plate-Asphalt under compressive and shear stress stateThe failure tests of 54 specimens of GFRP plate-asphalt under compression and shear stress state are carried out,which tests are in 6 working conditions and the loading angles of the specimens are in the range of 25 degree to 50 degree.The critical interface SIF of GFRP plate-asphalt is calculated according to the test datum.The failure mechanisms of the specimens are revealed and theK_?max?K_c criterion is established of the interface bonding strength of GFRP plate-asphalt under compressive and shear stress.?5?Interface fatigue performance study of GFRP plate-asphaltTaking composite beams of GFRP plate-asphalt as experimental objects,the three-point bending static load failure tests of SBI without interface crack and SBII with interface precast crack are carried out,and the test datum of failure form and failure load of test beam are obtained.On the basis of static load test,the test parameters,such as loading frequency,stress level and loading mode of fatigue test,are determined,and the fatigue tests of SBI and SBII composite beams are carried out.The effects of control parameters such as stress ratio and stress level on fatigue life of specimens are analyzed,and the fatigue life of SBI type and SBII composite beams under the same test conditions is compared.