Study On Composite Fracture Of Concrete With V Notch

The study of the fracture failure modes of concrete members with various openings under load is of great significance for understanding the fracture mechanism of concrete and the evaluation of residual strength of components with cracked orifices.In this paper,the composite fracture of concrete members with V cut is studied.The main research contents include: 1.Study the fracture process area and initiation load of concrete components with V notch;2,study the failure criterion of concrete with V notch;3,study the influencing factors of fracture failure of concrete members with V notch.In the aspect of experimental research,we designed and manufactured V notched specimens with different angles.The influence of different slit height ratio,different eccentricity and different V notch angles on fracture process zone,initiation load and failure load are studied by three point bending.The method of electrical measurement and digital image correlation is used to study the strain and displacement field in the vicinity of the notch tip.Based on the theory of finite fracture mechanics and generalized strain energy density criterion,the theoretical analysis is applied to analyze the crack propagation angle,initial fracture angle and initiation load of concrete specimens with V notch.Digital image correlation method is used to measure and calculate the size of the fracture process zone under different loading conditions of different Jacobi and different notch angles.Experimental and theoretical analysis show that:1)with the increase of the load,the length and width of fracture process zone is increasing,when the component into the instability stage,the fracture process zone size will reach the maximum,then decreased slowly;V type incision concrete cutting angle the greater the cracking load is small;the greater the gap ratio.The peak of fracture process zone sizes increased;when the V notch angle less than 120 degrees,the fracture process zone with incision angle increases;when the V notch angle greater than 120 degrees,the fracture process zone increases with the increase of cutting angle;eccentricity is large,complex parameter is larger,more destructive,since the greater the initial crack load,crack propagation angle increases.2)the finite fracture mechanics criterion is compared with other criteria.Whether the critical failure load or the crack propagation angle,the theoretical prediction value of the finite fracture mechanics criterion is the closest to the experimental result.3)the generalized strain energy density criterion has higher prediction accuracy than the conventional strain energy density criterion.