Axial Compression Behaviour Of FRP Confined Concrete Filled Steel Tube Containing Recycled Concrete Lumps

The concrete filled steel tubular structure has been widely applied in practical engineering.However,due to some factors such as corrosion,earthquake and improper construction,the bearing capacity of some concrete filled steel tube structures is.insufficient,which needs reinforcement.In recent years,some scholars have proposed a new type of FRP confined concrete filled steel tube,which can solve the problem of concrete-filled steel tube.The structure can also be used in the new structure.Its advantages include superior seismic capacity,good corrosion resistance and increase the axial bearing capacity of the component.Combined with the problem of building a large number of construction waste in China,a new type of composite structure is studied in this paper:FRP restrained steel tube regenerative mixed concrete.The composite structure consists of FRP outsourced cloth,steel tube and regenerated mixed concrete(mixed waste concrete in fresh concrete).This structure can be used effectively to make use of construction waste and turn waste into treasure,but its mechanical properties are not yet clear.In this paper,the axial compression test of 3 batches of 36 specimens of CFRP(carbon fiber reinforced composite)steel tube regenerated mixed concrete composite columns was carried out.The main work and conclusions are as follows:Taking the number of CFRP wrapped layer,the thickness of the steel pipe,the strength of new and old concrete,and the amount of waste concrete as the research parameters,the axial compression test of FRP confined recycled concrete is carried out,and the load displacement curve and the stress-strain curve of the core concrete are obtained.The test results showed that:(1)when the other parameters are same,have little impact without waste concrete on concrete filled steel tubular short column CFRP constraints of axial bearing capacity of mixing 30%;(2)when the other parameters are same,the core concrete stress-strain curve increases with the thickness of steel tube,but the enhancement effect is not obvious;(3)when the other parameters are same,affect the strength of the core concrete pressure on the bearing capacity of CFRP confined concrete filled steel tubular short column shaft big.And played a major role in the fresh concrete core in concrete strength;(4)when the other parameters are same,the CFRP layer CFRP constraint on the effect of mixed steel tube recycled concrete short columns under axial compression performance,a bearing capacity of steel CFRP constrained mixed recycled concrete short columns than steel without CFRP package mixed recycled concrete short columns,and with the outsourcing CFRP layer increased,the axial compressive strength of specimens increased and the ductility increases.(5)the stress strain model of FRP confined concrete filled steel tubular columns proposed by Teng et al can simulate the.stress-strain curves of recycled aggregate concrete columns in FRP confined steel tube recycled concrete columns.