Experimental Study On Seismic Performance Of Aeolian Sand Concrete Columns With Built-in Circular Steel Tubes

With the continuous development of urbanization,the number of construction projects continues to increase,and the demand for concrete also expands.The fine aggregate used in the preparation of concrete is generally natural river sand.Due to the scarcity of natural river sand resources,it has been unable to meet the current engineering needs.There is a large amount of aeolian sand in northwest my country.If aeolian sand is substituted for part of natural river sand to make concrete that can meet the performance requirements,on the one hand,it can avoid excessive mining of natural river sand and protect the natural environment and save resources.On the other hand,it is convenient to obtain local materials and save engineering costs.To promote the application of aeolian sand in practical engineering,this paper designed and produced 4 aeolian sand concrete columns with built-in circular steel pipes with different replacement rates of aeolian sand.The seismic performance of the specimens is studied through repeated low-cycle loading tests.The main research contents are as follows:(1)According to the experimental phenomenon,the failure form of each specimen is studied,the test data is sorted out to obtain the hysteresis curve and skeleton curve of each specimen,and the seismic performance indicators such as the bearing capacity,ductility,energy dissipation capacity,and stiffness degradation of the specimen are analyzed.The results show that when the replacement rate of aeolian sand is within 30%,with the increase of the replacement rate of aeolian sand,the bearing capacity,ductility,and energy consumption of the specimen are improved.When the replacement rate of aeolian sand is increased to 40%,the seismic performance of the specimen will decrease;The setting of the built-in round steel pipe core column can significantly improve the bearing capacity and ductility of the test piece,and delay the stiffness degradation rate of the test piece.(2)Two different damage models are used for seismic damage analysis of the specimens,one is the Ghobarah single-parameter damage model,and the other is the Park-Ang damage model modified in this paper.Substitute the test data into the model,and compare the calculation results with the damage index range.The results show that the revised dual-parameter seismic damage model considers more comprehensive factors than the single-parameter model,and is more in line with the damage evolution process of the specimen during the failure process.(3)On the basis of the test,perform regression analysis on characteristic point load and displacement,forward and reverse unloading stiffness and other data,the three-fold line restoring force model of the built-in circular steel tube aeolian sand concrete column is established,and the calculation formula of the built model curve is given.At the same time,the stiffness degradation law and hysteresis law of the specimen are described.Comparing the skeleton curve obtained by the test and calculation,it is confirmed that the two are in good agreement,which can provide a basis for the seismic performance analysis of the specimen.(4)Use the ABAQUS finite element analysis software to establish a finite element model of a concrete column with built-in circular steel tube aeolian sand,and compare the finite element output results with the test results to verify the rationality of the finite element model established in this paper.On the basis of this model,by changing the design parameters of the model,the influence of the axial compression ratio,the thickness of the built-in round steel pipe,and the strength of the built-in round steel pipe on the seismic performance of the test piece is analyzed,which provides a design basis for the application of the test piece in actual engineering.