Axial Compressive Performance Of Seawater And Sea Sand Concrete Square Short Columns Reinforced With FRP Bars And Stainless Steel Bars

The excessive consumption of fresh water and river sand by traditional concrete structures has caused a series of resource and environmental problems.At the same time,the 21 st century will be a century of competition for marine resources,and islands,reefs and coastal construction in China are extremely urgent.If seawater and sea sand concrete can be applied to building construction,not only the shortage of resources can be solved,but also the cost of construction and transportation can be saved.As a lightweight,high strength,good corrosion resistance material,FRP bar can be applied to seawater and sea sand concrete,but the characteristic of low elastic modulus,brittle fracture during compression needs to be improved.As a material with good corrosion resistance,the use of stainless steel bars in engineering is also restricted by the cost issues at this stage.Based on the above considerations,this paper proposed a new component form of seawater sea sand concrete column reinforced with FRP bars and stainless steel bars,and studied its axial compression properties.The main research contents and conclusions are as follows:(1)75 seawater and sea sand concrete square short columns were tested under axial compression,and the influences of reinforcement type,reinforcement ratio,concrete strength grade and FRP bars type on the failure mode,deformation coordination,bearing capacity and ductility of seawater and sea sand concrete columns were studied in this experiment.The results indicated that the ductility of seawater sea sand concrete column reinforced with FRP bars and stainless steel bars was improved and it had a ductile failure mode.(2)Based on the constitutive relations of FRP bars and stainless steel bars,the calculation formulas of bearing capacity of concrete columns reinforced with GFRP bars,concrete columns reinforced with stainless steel bars and concrete columns reinforced with FRP bars and stainless steel bars were proposed in this paper.Compared with the experimental results,it showed that the above formulas have good applicability and accuracy which error are within 15%.(3)Based on R.Park model,the ductility coefficients of concrete columns reinforced with GFRP bars,concrete columns reinforced with stainless steel bars and concrete columns reinforced with FRP bars and stainless steel bars were calculated,and the influences of reinforcement type and concrete strength grade on the ductility of concrete columns were analyzed quantitatively.The ductility of concrete columns reinforced with stainless steel bars is the largest,followed by the ductility of concrete columns reinforced with GFRP bars and stainless steel bars,and the ductility of concrete columns reinforced with GFRP bars is the smallest.The increase of the concrete strength grade would significantly reduce the ductility of the columns.