Model Test And CDP Model Study Of PC Cable-stayed Bridge With Crack Grouting Disposal

Prestressed concrete(PC)cable-stayed bridges play an extremely important role in China's transportation network in terms of number and span.It is found that the main girder of PC cable-stayed bridge under long-term overweight traffic load has frequent diseases and serious cracks.If not handled in time,the driving comfort will be affected slightly,and the safety of bridge structure will be threatened seriously.Conventional reinforcement means require traf-fic restriction or traffic interference.How to deal with cracked main girder of PC cable-stayed bridge quickly without affecting traffic becomes a problem that needs attention.The main work and achievements of this paper are summarized as follows1?On the basis of consulting relevant literature,the development history of PC cable-stayed bridges and the common methods and research status of bridge reinforcement are summarized;the theory of concrete constitutive model research is introduced in detail,including elasticity theory,plasticity theory,internal time theory and fracture damage theory;and the research status of constitutive relationship of ultra-high performance concrete(UHPC)is summarized for the follow-up study.The work provides a theoretical basis.2?Based on the background of a PC cable-stayed bridge,the section scale model test of the bridge was carried out.The test beams were loaded to failure under different working conditions,the cracks in the cracked area of the beam are treated by grouting and then loaded under the same working condition.The deflection,cable force and crack development during the two loading tests are monitored and compared.The results show that the stiffness of PC cable-stayed bridge girder decreases seriously under overweight traffic load,and crack grouting treatment can significantly improve the stiffness of damaged girder,but it is difficult to restore the stiffness until it is not damaged;crack grouting treatment of the main girder is not as crack-resistant as the original girder,but still meets the relevant requirements of the Code.3?Based on the Code and existing research,the damage parameters of concrete damage plastic(CDP)model are selected,and the input data of CDP model used in ABAQUS are deduced,including the damage input data of C50 concrete and UHPC.4?The ABAQUS numerical model of PC cable-stayed bridge segmental test considering plastic damage is established,which includes model 1 and 2,which fully simulate the original test and crack grouting test.Model 3 of UHPC layer is added to the bottom of the test beam,and the finite element calculation results are compared with the test data.The results show that the deflection,cable force and crack development laws calculated by FEM are close to the experimental data and have little difference.Increasing the UHPC layer in the tension zone at the bottom of the beam can greatly improve the crack resistance of the damaged main beam and the stiffness of the damaged main beam.The above results show that the finite element model is in good agreement with the test,and the CDP model can better simulate the mechanical properties of concrete structures under complex loading conditions.