Experimental Research On Axial Compression Performance Of GFRP Tube Restrained Seawater And Sea Sand Recycled Concrete Short Columns

In recent years,with the rapid development of the construction industry,the demand for concrete has increased year by year,which has led to an increase in the consumption of natural aggregates,river sands and fresh water.Our country is facing a shortage of various construction material resources.At the same time,the generation of large amounts of construction waste also caused severe environmental damage.In order to cope with the problem of resource shortage and environmental damage,recycled aggregates are used instead of natural aggregates,and seawater and sea sands are used instead of freshwater and river sands,seawater and sea sand recycled concrete is produced,combined with the related excellent characteristics of GFRP tube,such as corrosion resistance,a GFRP tube restrained seawater and sea sand recycled concrete composite column is proposed.In this paper,the GFRP tube restrained seawater and sea sand recycled concrete short column is taken as the research object,and its mechanical properties under axial compression load are discussed.A total of 16 specimens are designed in this paper,each set includes the same 2 specimens,a total of 32 specimens.Through the axial compression test of GFRP tube restrained seawater and sea sand recycled concrete short columns,the axial compression process test phenomenon of composite columns and its failure mode are described in detail.Based on the test data,draw and analyze the load-displacement curve and stress-strain curve of each specimens.At the same time,the influence of seawater and sea sand on the axial compressive performance of composite columns was discussed through the comparison between GFRP tube restrained seawater and sea sand recycled concrete short columns and GFRP tube restrained recycled concrete short columns.In addition,this study set a total of 4 research parameters,namely the replacement rate of recycled aggregate,the strength grade of recycled concrete in seawater and sea sand,the wall thickness of GFRP tubes,and the size of the test specimens.By comparing the characteristic values of axial compression test,load-displacement curve and stress-strain curve,the influence of different parameters on the axial compression performance of GFRP tube restrained seawater and sea sand recycled concrete short column was discussed and analyzed.Finally,the stress mechanism of GFRP tube restrained seawater and sea sand recycled concrete short columns under axial load is described.On this basis,through regression analysis of experimental data,the existing FRP confined concrete ultimate strength model is revised,and put forward the formula for calculating the ultimate bearing capacity of the combined column under the action of seawater and sea sand.The results show that the theoretical value and the experimental value have a high degree of agreement.In addition,a modified combined column stress-strain relationship model is also given,and the comparison shows that the theoretical curve is in good agreement with the experimental curve.