Analysis Of Seismic Performance Of Y-shaped Bridge Piers Under Freeze-thaw Environment Based On ANSYS Workbench

With the continuous improvement of efficient transportation system in contemporary society,the construction of transportation infrastructure is gradually increasing.Reinforced concrete Y-shaped piers are widely used in urban viaduct and overpass because of their lightweight appearance and good stress characteristics.China has a vast territory and obvious regional characteristics,the freeze-thaw damage of concrete easily occurs in cold and severe cold regions such as Northwest,North China and Northeast China.This paper used a combination of theoretical analysis and numerical simulation to focused on the mechanical properties of concrete materials after freeze-thaw damage.The mechanical performance under monotonic loading and seismic performance under low-cycle repeated loading of Y-shaped piers of urban viaducts under freeze-thaw conditions.The specific research work is as follows:1.Based on the constitutive relationship of unfreezing thawing concrete,the relationship between the number of freeze-thawing cycles and the parameters of freeze-thawing damage concrete constitutive model was obtained by regression analysis of the existing parameters of freeze-thawing cycle test.the stress-strain full curve equation and damage evolution parameters of C30 and C40 concrete after freeze-thawing cycle were obtained by fitting,which could be used for nonlinear analysis of Y-shaped bridge piers in freeze-thaw environments.2.According to the constitutive model obtained by fitting,focus on the Y-shaped piers of urban viaducts that had suffered long-term freeze-thaw damage in severe cold environments,a finite element numerical model was established based on ANSYS Workbench software.The mechanical performance analysis under monotonic loading was carried out,and the influence of the number of freeze-thaw cycles,axial compression ratio,concrete strength,and loading direction on the bearing capacity index of Y-shaped bridge piers were obtained.3.Through the establishment of 32 sets of different finite element models,the pseudo-static seismic performance analysis under low-cycle repeated loads was carried out,and the effects of the number of freeze-thaw cycles,axial compression ratio,concrete strength,and loading direction on the hysteresis curve,skeleton curve,ductility,energy dissipation capacity,and stiffness of Y-shaped bridge piers after freeze-thaw damage are studied.Indicated that freeze-thaw damage has an adverse effect on the ultimate bearing capacity and seismic performance of Y-shaped bridge piers either CIS bridge or Cross bridge directions,the peak load and displacement ductility coefficient of the pier decrease with the increase of freeze-thaw cycles,which provided a theoretical reference for improving the seismic performance of Y-shaped piers of urban viaducts under freezing and thawing environments.