Research On Bond-slip Performance Between CFRP Bar And Seawater Sea-sand Concrete

Due to the excellent mechanical properties and durability of Carbon Fiber Reinforced Polymer(CFRP),CFRP bars and seawater sea-sand concrete structures are widely applied.The CFRP bars in the structure can perfectly solve the problem of steel corrosion caused by chloride ions in seawater and sea-sand.However,there is still a lack of comprehensive theoretical research on the bonding performance between CFRP bars and seawater sea-sand concrete.Therefore,pull-out experiments,numerical simulations,and theoretical calculation were used to study the bond behavior between CFRP and seawater sea-sand concrete.The failure mechanism,cohesive force distribution,constitutive relationship,and influencing factors in the performance have been systematically analyzed.Firstly,the pull-out test of short buried CFRP bars was carried out,and the test results were obtained.Data such as the ultimate bond strength and slip value during the process were recorded,and the bond-slip curve of CFRP seawater sea-sand concrete was concluded.At the same time,several failure modes of specimens in the test were observed and analyzed combined with SEM Scanning results.In addition,orthogonal design was used to in this test analyze the influencing factors of the bond strength between CFRP bars and concrete.Secondly,a numerical model of the pull-outtest was established through the finite element software,and the internal forces and parameters were further analyzed.After the model was established,it was verified through the failure mode and the bond-slip curve,and the stress state of each part in the bond-slip process and the bond force distribution were analyzed by the model;Parameter analysis was later used to studied the influence of concrete strength,thickness-to-diameter ratio,CFRP shape on the ultimate bond strength and peak displacement of CFRP bar concrete.Finally,through the calculation and fitting of the test and finite element results,the constitutive relationship and the change of influencing factors are quantitatively analyzed.The distribution function of the bond stress is obtained by calculation,and a method for roughly calculating the distribution of the bond force with the average stress is proposed;the bond-slip expression under different failure modes is obtained;finally,,through the relational expressions of influencing factors and the actual damage conditions obtained before,the reasonable value range of each factor that affects the CFRP bar concrete bond slip is judged,providing a reference for the practical application of CFRP bars seawater sea-sand concrete in engineering.