| Due to the influence of freeze-thaw erosion,some structural load-bearing components will withdraw from work in advance,and most of them are strengthened and repaired to achieve the purpose of the continuing the functionality and economic applicability.because CFRP sheet has good material properties,it's application prospects in engineering is bright,so it is worthful to do research about the dynamical characteristics of CFRP reinforced members.In this paper,theoretical analysis and simulation of ABAQUS are used to analyze the axial compression behavior,load-displacement curves and ductility etc of ordinary concrete columns,unstrengthened freeze-thaw damaged concrete columns and strengthened freeze-thaw damaged concrete columns by CFRP sheets.Particularly include:The test model is divided into 16 different specimens because of two different factors,including the number of freeze-thaw cycles and whether to use CFRP sheet outside to make a full envelope reinforcement,for the freeze-thaw damaged plain concrete specimen,on the basis of existing experimental materials,the cross-section area and axial compression capacity of concrete are reduced and modified by establishing a quantitative relationship between freezing and thawing cycles,and the calculation method of axial compression capacity of plain concrete columns was deduced,which is suitable for different times of freeze-thaw cycles.As for reinforced concrete columns after freeze-thaw damage,the cross-sectional area of damaged model,ultimate tensile load and adhesion between steel and concrete were analyzed,and took the effect of freeze-thaw into account.The axial resistance of reinforced concrete members after freeze-thaw damage is obtained theoretically by calculation.When the damaged concrete specimen is strengthened with CFRP sheet,the tensile load of CFRP sheet is modified by analyzing the influence of some factors,such as the reinforcement method and material properties on the strengthening effect.The bearing capacity of the CFRP sheet and concrete which is effectively restrained by CFRP sheet is regarded as a whole,and the compression capacity of the composite partwas analyzed.On the basis of the theory of superposition of forces,the calculation method of axial compression capacity of freeze-thaw damaged concrete columns strengthened with CFRP sheet was deduced.100 cycles of freezing and thawing is a critical value,when the number of freeze-thaw cycles is less than 100 times,the each theoretical value of axial compression capacity of the specimens is smaller than the experimental values,and the average error is less than 20%,it shows that the theoretical analysis method is reasonable.Using ABAQUS to analyze the effect of temperature field and concentrated node displacement in two steps,the simulation results of different models subjected to freeze-thaw cycles and axial compression were obtained in order,It shows that the axial compressive capacity of each freeze-thaw damage model is decreasing,when freeze-thaw damaged specimens of plain concrete strengthened with the combination of CFRP,the failure form of the specimens are brittleness and it is more effective to improve amplitude of increase in load capacity of the damaged specimens than the reinforced concrete columns strengthened with CFRP sheets.Considering the effect of the ductility of the member on the durability,the ductility of strengthened members is discussed by analyzing the load-displacement curve,and the ductility coefficient of the model is calculated.The axial compression behavior of models under different freeze-thaw cycles were analyzed,the simulated value is compared with the experimental value and the calculated value.The rationality of the theoretical formula has been indicated by calculating the average error between the three,which provides a reference for further research. |
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