Study On The Behavior Of CFRP Confined Steel Reinforced Recycled Concrete Column Under Axial Compression

Recycled concrete is a kind of building material with low carbon and energy saving.Section steel has good ductility.CFRP(carbon fiber reinforced polymer)has the advantages of high strength,high ductility and corrosion resistance.It can not only make use of the high-strength restraint ability of CFRP,but also effectively enhance the ductility of recycled concrete structure,which has a green application prospect.In order to study the mechanical properties of recycled concrete columns confined by CFRP under axial compression,the following work is carried out:11 specimens were designed and manufactured,and the failure process and failure mode of CSRRC specimens under axial compression were analyzed in detail.Considering the replacement rate of recycled coarse aggregate,the number of layers wrapped by CFRP,the strength grade of recycled concrete,the steel ratio and the slenderness ratio,the influence of the axial compression performance of the specimen is considered.Through the comparison of test data,the paper analyzes the differences of stress-strain curve,load displacement curve,axial compression performance index and axial compression bearing capacity under different parameters.The test results show that CFRP confined Steel reinforced Recycled Concrete Columns have good axial compression performance,and CFRP has fully developed its high-strength restraint performance,effectively improving the axial bearing capacity of the specimens,with the maximum increase of the axial bearing capacity of 55%.The ductility of the specimen can be effectively improved by the built-in profile steel,and the maximum yield displacement can be increased by 14.3%.The replacement rate of recycled concrete has little effect on the bearing capacity of axial compression,and the maximum reduction of peak bearing capacity is 6.4%.The strength of recycled concrete can significantly improve the axial bearing capacity of the specimen,but the ductility is reduced,and the maximum yield displacement is reduced by 9.9%.The influence of slenderness ratio on the axial bearing capacity of the specimen is not significant,and the maximum reduction of the axial bearing capacity is 4.5%.Based on the test results,the stress-strain relationship of recycled concrete confined by CFRP and stirrup is analyzed.The compressive strength model of FRP confined concrete is put forward by Teng,J.G,and the calculation formula of the ultimate bearing capacity of recycled concrete columns confined by CFRP is established by referring to relevant codes.It is found that the error is less than 10%by comparing the test value with the calculated value,which can provide reference for related projects.