Mechanical Properties Of C-FRCM Confined Concrete Short Columns Under ICCP

In a previous study,we found that energization of the ICCP system will cause changes in the interface properties of the carbon fiber mesh and the cementitious material in the C-FRCM composite material as the auxiliary anode,thus affecting the confinement effect of the C-FRCM composite material.This research is based on the above problems to study the axial compression performance of C-FRCM reinforced concrete short columns under the influence of ICCP electrification,and then to explore the confinement effect of C-FRCM on concrete short columns under ICCP electrified conditions.There are three main research topics in this thesis:The effects of different cementitious material types and mesh types on the uniaxial tensile properties of C-FRCM composite were explored by conducting uniaxial tensile tests on 8 types of C-FRCM composite materials.The results show that:(1)The incorporation of chopped carbon fibers significantly increases the cracking strength of C-FRCM.The optimal additive amount of chopped carbon fiber is 0.75%.(2)The node of the carbon fiber mesh was solidified treatment,which can effectively improve the interface property of the fiber and the cementitious material,thus improving the uniaxial tensile property of C-FRCM.(3)The multi-crack and high ductility of ECC has improved the mechanical properties of the composite material in a certain degree.(4)The C-FRCM tensile stress-strain curve was simplified and fitted basing on the current specifications.The fitted curve can better characterize the stress-strain characteristics of the C-FRCM composite material.Axial compression test of C-FRCM confined concrete column.The effects of different types of cementitious materials and fiber mesh treatment on the axial compression performance of confined concrete short columns were studied.The results show that:(1)The type of cementitious material will affect the confinement effect of carbon fiber on the concrete column.Therefore,the mechanical properties of the C-FRCM composite material should be studied and calculated in the subsequent investigation.(2)The confinement effect of one layer of fiber mesh is not enough,which is very limited for confinement effect of concrete columns.(3)When C-FRP was used as confinement material,the specimen is often brittle when it fails.When C-FRCM was used as the confinement material,the failure process of the specimen is more moderate.Specimen still has ductility after the ultimate strength.(4)Node treatment is only effective for the confinement of one layer of fiber mesh.There is not much difference in whether the node is cured for the confinement of 2,3,and 4 layers of fiber mesh.(5)According to the results,the axial compression constitutive model of the confined concrete column suitable for the C-FRCM composite material is proposed in this paper.The proposed model can better simulate the experimental stress-strain curve relationship.Axial compression test of C-FRCM confined concrete short column was conducted under the condition of ICCP electrification.The effects of different ICCP application time,current density and the type of cementitious material on the axial compression performance of confined concrete short column were explored.The results show that:(1)When the electricity charge density of ICCP is less than 6.22×10~5C/m~2,the axial compression strength of the specimen keeps increasing with the increase of the electricity charge density.When the electricity charge density is greater than 6.22×10~5C/m~2,the axial compression strength of the specimen decreases with the increase of electricity charge density.(2)The experimental data under ICCP electrification conditions were used to modify the ultimate strength calculation model obtained under normal conditions.Electric charge density was introduced into the ultimate strength enhancement coefficient,so that the ultimate strength of C-FRCM confined concrete short columns under different ICCP electrical charge densities can be predicted.