Failure Mechanism Of FRP Reinforced Concrete Column With Initial Defects

Carbon Fiber Reinforced Plastics reinforcement technique is regarded as a kind of the high applicability and value-added reinforcement method. It has been started to get a large number of applications in the civil engineering. It has a great deal of extension studying value and the benefits of socio-economic. At present, the performance of circular cross section concrete column by constraints of the fibers have been more researched, however, most of them are under the conditions of the assumption that perfectly bonded between FRP and the reinforced concrete columns. scientific research of fiber reinforced concrete columns with defects are relatively few.Initial defects is due to the concrete surface layer peeling, damaged or even a little structure layer in the process of FRP reinforcement between concrete and FRP stripping or gap in the external natural environment for a long time or under the action of external force. although national regulation is always claiming to preprocessing before reinforcement, but in practice, due to the factors that the external environment condition of reinforcement is poor and the position of the strengthening component is not easy to operate, this kind of defect is inevitable because of the initial conditions. To research the influence that initial defect act on mechanical properties and failure of reinforcement column, which is a great significance to improve the design standard and the life cycle of structure after predictive ability!This text analyzes the influence of initial defects on the mechanical behavior of reinforced concrete column From macro and micro Angle qualitatively, and uses the test data of fiber reinforced concrete columns from the tests that published at home and abroad of fiber reinforced concrete columns. Compare the strength of the existing models to get a better optimal model, and adopt the test data of this text, it is based on the existing strength model, this text has been used EVIEWS, MATLAB software to consider the effects of initial defects, and the correction strength model is obtained by curve fitting where considering the initial defects.Select 40 roots for loading on displacement control by liquid pressure testing machine, study on the change rules of critical value under the influence of the factors include the parcel layer, cross section size: critical defect value increased with the increase of the layer number of packages, but rises in reducing; Critical defect value decreases with the increase of section size, but the reduction in decreasing. And through observing the failure pattern of reinforced column in the process of loading, it is concluded that the reinforcement column destruction form the critical defect value has a great change before and after. And the failure form of reinforced column has taken place by axial compression failure to oblique-shear failure, it demonstrates the influence of the initial defects on damage form.Mechanical properties of CFRP reinforced concrete column was studied preliminarily by using ABAQUS under the action of axis pressure, the Change regularity of critical defect with the parcel layer number and section size can be gained by analyzing. By studying the concrete damage model, establishing CFRP reinforced column model with initial defects, through simulation found that as the initial defect value increasing, there must be critical defect value, compared with the results of test, it has been demonstrated the change trend of critical defect from perspective of the simulation and experiment on reinforcement layer and section size. Study on the mechanical behavior of CFRP reinforced concrete columns under the action of the eccentric pressure briefly, found that reinforced column had a greater influence on the bearing strength with the increase of eccentricity, and mechanical performance under the same eccentricity is improved with the increase of the parcel layer. Study on changing rule of critical defects with the parcel layer under the condition of small eccentric, it is known that critical defect values under the action of the eccentric pressure are smaller than under the axial compression.