Seismic Damage Behavior Of Aeolian Sand Reinforced Concrete Columns With I-shaped Structural Steel

In recent years,the global "desertification" has become more and more serious,and the human living environment is deteriorating.Meanwhile,with the acceleration of China’s urbanization process,the construction of various domestic infrastructures continues to increase.As one of the main building materials for preparing concrete,the demand for river sand is also increasing.This situation has caused the natural sand resources with serious uneven distribution to be depleted day by day,and the extensive use of natural sand will seriously pollute the environment and increase the project cost.In this situation,if aeolian sand is used to mix concrete in arid and semi-arid areas of China,it can not only reduce the dependence on natural sand,but also alleviate the harm of aeolian sand,which is of great significance to promote the harmonious development of human and environment.Based on the features of high bearing capacity,high stiffness and good seismic behaviors of steel reinforced concrete columns,the paper proposes to form steel reinforced concrete columns with aeolian sand to delay the emergence of plastic hinges at the end of the columns and improve the aseismic performance of the columns.In this paper,the seismic performance of steel reinforced aeolian sand concrete columns are studied by low cycle cyclic loading test,and the seismic damage analysis and finite element analysis are carried out.The main work and conclusions are as follows:1.Experimental study on low cyclic loadingIn this paper,a total of 4 steel-aeolian sand concrete column specimens with different replacement rates of aeolian sand were designed and produced.The failure mode,bearing capacity,hysteretic behavior,skeleton curve,energy dissipation capacity,ductility coefficient,stiffness degradation law and deformation characteristics of the specimens were studied by applying low cycle repeated load.The results show that:(1)Compared with the ordinary aeolian sand concrete column specimens under the same aeolian sand replacement rate,the peak load,ductility and cumulative energy consumption of the steel-aeolian sand concrete column specimens are significantly improved;(2)With the increase of the replacement rate of aeolian sand,the peak load and ductility of the specimens first increase and then decrease,and 30 % aeolian sand replacement rate has the best effect.Under this replacement rate,the hysteretic curve of the steel reinforced aeolian sand concrete column specimens present a very full shuttle shape,with larger ultimate deformation and better ductility;(3)Compared with the ordinary aeolian sand concrete column specimens under the same aeolian sand replacement rate,the stiffness degradation curve of the steel aeolian sand concrete column specimens is more gentle,and the stiffness degradation rate is smaller;(4)With the increase of horizontal displacement,the equivalent viscous damping coefficient and cumulative energy consumption of each specimen increase continuously.Under the same replacement rate of aeolian sand,the equivalent viscous damping coefficient and cumulative energy consumption of steel aeolian sand concrete column are significantly higher than that of ordinary aeolian sand concrete column.2.Seismic damage analysisBased on the above experimental research,the seismic damage performance of the steel-reinforced aeolian sand concrete column is studied,and the Park-Ang damage model is further modified.The modified model can better reflect the evolution law of seismic damage of steel-aeolian sand concrete columns,and provide basis for the analysis of seismic damage.The seismic damage analysis shows that under the same displacement,with the increase of aeolian sand replacement rate,the damage index of the specimen decreases gradually.The damage index of the steel reinforced concrete column with the replacement rate of 30% of the aeolian sand is the lowest,and the seismic performance is relatively optimal.3.Finite element analysisThe hysteretic behavior of steel-aeolian sand concrete column under low cyclic load was analyzed by using ABAQUS software,and the skeleton curve of the column members was obtained.The test results and the finite element analysis results were compared and analyzed,and the rationality of the finite element analysis results was verified.Then,by adjusting the other parameters in the model,studied the concrete intensity,axial compression ratio,ratio of longitudinal reinforcement and depth of wind-blown sand,I-steel model of steel-concrete column the influence law of seismic performance.