Mechanical Properties Study On Cfrp-confined Recycled Aggregate-seasand Concrete Columns

In recent years,people gradually realized that the ecological environment problems such as the sand-free excavation in the river,construction waste,and fresh water resources have seriously affected the normal human life and development.At the same time,the construction industry's original resources were continuously mined and wasted.People have a deeper understanding of such concepts as "building a resource-saving society" and "building a sustainable society." The main problem at present is to reduce the consumption and waste of the original building resources,and to meet the growing demand for resources in the construction market.Therefore,this paper proposed recycled aggregate sea-sand concrete(RASC),an effective combination of recycled green aggregate,sea sand,and seawater,to replace ordinary concrete and introduce lightweight,high-strength,corrosion-resistant steel.The structural reinforcement of FRP materials not only realizes the recycling of resources,but also significantly increases the strength and ductility of the structure,laying a solid foundation for the application of FRP in combination with RASC.In this regard,the main content of this article includes:(1)The RASC was developed: The performance parameters of the aggregates were tested and studied.The compressive strength and workability of the cubes were used as the main criteria for evaluation.The effect of RASC concrete strength under seven operating conditions was studied.The effects of water-cement ratio,age,treatment of coarse aggregates,replacement ratio of coarse aggregates,etc.on the strength of concrete were discussed in detail.The optimal mix ratio was obtained through experiments,which laid the foundation for the follow-up work.(2)The CFRP test and the axial compression test of 42 CFRP confined RASC short columns were performed:The effects of FRP layer number,chamfer ratio and replacement ratio on ultimate strength and ultimate strain were analyzed.The differences between CFRP confined plain concrete square column and CFRP confined RASC square column were compared and analyzed.At the same time,the ultimate strength and ultimate strain model for CFRP confined RASC are established.Finally,Zhou and Wu's stress-strain model is used to predict the test in this paper.The prediction results of the three mechanical models are consistent with the experimental results(3)Axial compressive test of 12 corrosion-resistant tubes,27 CFRP confined RASC-corrosion-resistant tubes(stainless steel tubes and aluminum alloy tubes)composite short column,and tensile test of 24 corrosion-resistant dog bone specimens,and were performed.Reference to the previous 6 CFRP confined RASC results,from the perspective of the contribution of the bearing capacity and the perspective of the individual variables(hollow ratio,replacement ratio,and pipe type),the influence of the mechanical properties of the composite component was analyzed.The ultimate strength model and ultimate strain model of the previous chapter were used,and the ultimate strength model was revised.Finally,the stress-strain model of Zhou and Wu was used to predict the stress-strain curve of the core concrete.The predicted values are consistent with the experimental results.