| The sea-crossing bridges serving in subtropical coastal area are under the coupling action of seawater corrosion,high temperature environment and vehicle fatigue load,the action has a significant impact on the durability of bridges.In order to investigate this impact,setting the Carbon Fibre Reinforced Polymer(CFRP)strengthened reinforced concrete(RC)beams as the research object,the effects of hot-seawater environment and fatigue load on the beams were investigated.The finite element software ABAQUS was used to establish the prestressed CFRP reinforced RC beam model,the environment temperature is 10℃,35℃ and 50℃,and Na Cl solution concentrations is 3% and 5%,respectively.The fatigue performance of the prestressed reinforced RC beam in the subtropical coastal environment was studied and analyzed.The main research contents and conclusions of this paper are as follows:(1)Based on the existing test data and models,the degradation of the compositive materials and CFRP-concrete interface performance of CFRP reinforced RC beams under hot-seawater environment and fatigue load were considered respectively.A constitutive model of CFRPstrengthened RC beams fatigue performance under temperature-seawater environment was established,and the finite element software ABAQUS was used to solve it.Considering the failure modes of main bar failure and interface debonding of RC beams strengthened by CFRP in hot-seawater environment,the fatigue failure criterion was introduced and the fatigue life prediction model of RC beams was established.The model can predict the fatigue life and failure mode of RC beams strengthened by CFRP.The reliability of the model is verified according to the existing experimental data,the maximum difference under static load between the finite element results and the experimental results is 12.1%,and the average difference under fatigue load is less than 20%,the comparison results show that the experimental results are in good agreement with the theoretical results.(2)The fatigue behavior of RC beams strengthened by non-prestressed CFRP in hotseawater environment was studied by using the model established in this paper.The results show that: 1)the environment has a significant effect on the fatigue deformation of RC beams.With the increase of temperature and Na Cl solution concentration,the mid-span deflection of RC beams increases faster;2)The hot-seawater environment will increase the stress of the main bar and CFRP in the mid-span,which will accelerate the damage evolution of the interface and the damage accumulation of the bar,and leading to the reduction of the reinforced beam life;3)Different hot-seawater environments and loads will lead to different fatigue failure modes of RC beams strengthened by CFRP.With the increase of temperature,Na Cl solution concentration and load,the failure modes of RC beams strengthened by CFRP gradually change from the failure of main bar to the failure of CFRP-concrete interface debonding.(3)Using the model established in this paper,the fatigue performance of prestressed CFRP reinforced RC beams under hot-seawater environment is studied.,the results show that: 1)the increase of fatigue load has limited influence on the growth rate of the deflection of the reinforced beam but has a significant impact on the damage of main bar and interface.With the increase of the load,the damage growth rate of the main bar and interface becomes faster;2)The fatigue life of prestressed beams decreases with the increase of load,temperature and Na Cl solution concentration.When the failure mode is the main bar rupture,the fatigue life of the strengthened beams can be improved by applying prestress to CFRP,but the improvement will be weakened under large loads.When the failure mode of the structure is changed to interface debonding,the fatigue life of the strengthened beams will decrease with the increase of prestress degree.3)The effect of hot-seawater environment on the interface damage of prestressed beams is more significant than that of non-prestressed beams. |
PDF Full Text Request