| In recent years,concrete-filled steel tube structure has been widely used in bridges,stations,commercial buildings and other engineering fields,and has achieved good results.Among them,the hollow concrete-filled steel tube column has attracted much attention due to the engineering needs of its cross-sectional form and unique mechanical properties.Local buckling failure of external steel tubes often occurs in concrete filled hollow steel tubes under axial compression.In order to improve the bearing capacity of the structure,a new type of composite structure is constructed by wrapping glass fiber composites around the hollow concrete-filled steel tube structure,which is expected to improve its mechanical properties.At present,there are few related experiments and numerical simulation results for such components.In this paper,based on the cohesion zone model（CZM）,the numerical analysis method of axial compression and hysteretic behavior of glass fiber reinforced polymer（GFRP）confined hollow concrete filled steel tubular columns is studied,and the validity of the numerical model is verified by comparing with the experimental results.Based on the numerical model,the effects of main design parameters（including concrete strength,geometric characteristics of hollow column section,number of externally confined GFRP layers,diameter-thickness ratio of steel pipe and yield strength of steel tube,etc.）on the mechanical properties of GFRP confined hollow concrete filled steel tubular composite columns are studied.The results show that CZM is suitable for the study of GFRP bond interface of GFRP confined hollow concrete filled steel tubular composite columns;Increasing the concrete strength grade,the number of GFRP layers,the thickness of the steel pipe or the strength of the steel can all improve the load-bearing performance of the component,but at the same time it may also increase the lateral deformation of the GFRP bonding layer,which may lead to the risk of local debonding or fracture of GFRP Increase;Compared with reducing the diameter-to-thickness ratio of steel pipes,increasing the yield strength of steel pipes has more obvious advantages in improving the restraint effect on concrete,restraining the interlayer displacement of the GFRP bonding section,and reducing the failure risk of the GFRP reinforced layer.This paper derives the formula for predicting the bearing capacity of GFRPconstrained hollow concrete filled steel tube columns under axial compression.Through the comparative analysis of the predicted results of this paper,the existing research results and the test results of this paper,it is shown that the prediction formula of bearing capacity proposed in this paper is in good agreement with the actual value. |
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