Experimental Study On Axial Compressive Behavior Of Stainless Steel-Sea-sand Concrete-GFRP Composite Columns

The promotion of sea sand concrete is benefit to alleviate the shortage of river sand,however,it is easy to cause steel corrosion.By using the advantages of fiber-reinforced polymer/plastic(FRP)and stainless steel in corrosion resistance and the principle of confined concrete,this paper put forwards a new type of composite column,which called Stainless Steel-Sea-sand Concrete-GFRP Confined Sea-sand Concrete Column(or SSCFSC column in short).The composite column is composed of external stainless steel tube,built-in GFRP tube,which is filled with sea sand concrete between the two tubes and the GFRP tube.On the basis of promoting the utilization of marine resources,the performance of structural members is optimized.In order to analyze the anti-stress performance of this new column,this paper tests the monotone axial pressure of 8 SSCFSC short columns,2 concrete filled steel tubular columns(CFST column in short)and 12 GFRP confined sea-sand concrete columns(FSSC column).These tests aim to analyze the axial load-displacement curve of the composite column,load-strain of the stainless steel tube in the middle of the column,and load-strain relationship of the GFRP tube.Furthermore,this paper also discusses the influence of the shape of stainless steel tube,whether there are built-in GFRP tube,and the thickness and diameter of the GFRP tube.And through the ABAQUS finite element software,the whole process of axial compression simulation calculation of the above specimens was carried out,and the influence parameters of the diameter,thickness,thickness of stainless steel pipe,core concrete grade and annular concrete grade of GFRP tube were expanded and analyzed.The test and finite element calculation have reached the following conclusions:(1)The development of the load-displacement curve of a circular SSCFSC column can be divided into four stages,that are,elastic rising,elastoplastic rising,falling and rising development.Compared with the circular section specimen,square SSCFSC column has no obvious elastoplastic ascending section.Elastic and elastoplastic sections are two typical characteristics of FSSC column load displacement.(2)The bearing capacity and deformation of SSCFSC columns are better than that of traditional CFST columns.GFRP content can slow down the buckling of steel,increase the bearing capacity as well as limit the expansion deformation of the specimen.In the similar cases of GFRP content,increasing the diameter of the GFRP tube can better improve the axial compression performance of the SSCFSC column.When the internal concrete cross-section is approximate,the circular steel tube is much better than square steel tube of binding.(3)ABAQUS finite element calculation is in good agreement with the trend of the loaddisplacement curve obtained from the test results,which well explains that the falling part of the curve is affected by the failure of FRP tube.The results of parameter analysis show that increasing the diameter of the GFRP tube can improve the bearing capacity of the SSCFSC column;the grade of core concrete has more obvious effects on the bearing capacity of specimens than that of outer ring concrete;the thickness of the stainless steel tube has a great influence on the ductility of the test piece.