| Restraining concrete to improve the mechanical properties and deformation capacity of concrete structures,and to improve the seismic performance of structures has always been the goal pursued by academia and engineering.In this paper,the constrained layer of composite columns is made of hybrid fiber cement-based composite materials,and plain concrete is cast inside to form composite columns.The axial compression performance of hybrid fiber cement-based composite composite columns is studied.Considering the thickness of the restraint layer,the strength of the hybrid fiber cement-based composite material of the restraint layer,and the strength of the core concrete,18 composite column test pieces were designed and manufactured.Through the experimental analysis,the following results were obtained:1.The biggest factor that affects the crack morphology when the composite column is destroyed is the strength of the cement-based composite material in the constrained layer.The greater the strength,the more severe the specimen damage.2.When the thickness of the constrained layer is thicker,the corresponding curve falling section is more gentle.In general,the load-strain curves of specimens with constrained layer thicknesses of 62.5mm and 75 mm are similar;the higher the strength of the core concrete and the strength of the cement-based composite material of the constrained layer,the steeper the decline of the load-strain curve of the specimen.3.The influences of the thickness,strength of the constrained layer and the strength of the core concrete on the peak load,peak strain and ductility coefficient of the composite column are analyzed.Based on the principle of balance,local compression,and statistics,a formula for calculating the bearing capacity of a composite column was established,and the calculated value basically coincided with the test value.Based on the test data statistics,a calculation model for the peak strain of the composite column was established.Change of strain.4.It is verified that the stress-strain model of the composite column conforms to the Zhenhai model.Based on the test data,considering the thickness-diameter ratio,the strength of the internal and external materials,and the strength ratio,the system parameters of the Zhenhai model are revised to establish a composite column stress The modified strain curve has passed the Zhenhai model,and the model curve and thetest curve agree well. |
