| Carbon fiber-reinforced polymer composites(CFRP)have good application prospects in the fields of strengthening and repairing bridge and building structure due to its light weight,high strength,fatigue resistance and design ability,etc.Externally bonding CFRP to reinforce such structure is an effective method to improve its bearing capacity and fatigue life.It mainly transfers part of the stress of the damaged structure to the CFRP material through the bonding interface formed by the adhesive and CFRP and the damaged structure.The bonding system composed of the two share the corresponding load to achieve the effect of reinforcement and repair.However,the adhesive is usually composed of high molecular polymer,and its performance is greatly affected by temperature.Therefore,it is of great significance to study the influence of temperature and adhesive types on the mechanical properties of CFRP-reinforced steel structure.To this end,this paper carries out the static tensile test of the CFRP plate-steel plate double lap joint under temperature to explore the effect of temperature on the mechanical properties of the bonding interface.Then carry out the static tensile test of the CFRP plate fully covered by the adhesive reinforcement of the notched steel plate under temperature,explore the mechanical properties of the CFRP plate to strengthen the defective steel plate,and provide a scientific basis for the use of CFRP to strengthen the damaged steel structure.The specific work is as follows:(1)The tensile work of 24 CFRP plate-steel plate double lap specimens were carried out with 2 specimens in each group under the combination of 3 adhesives and 4 temperatures.Taking into account the discreteness of the test,some specimens with large differences in results were supplemented and replaced.Adopt a bonding interface of sufficient length(200mm)to explore the failure characteristics and load-displacement relationship of the adhesive bonding interface under temperature.A third-order polynomial was used to fit the strain,and the influence of temperature on the interfacial stress transfer law and the bond-slip constitutive relationship was analyzed.It provides interface performance guarantee for the use of CFRP plates to strengthen and repair damaged steel structures under high temperatures in natural environments.(2)Under the combination of 2 steel plates with different notch sizes and 3 adhesives at normal temperature,each group of 2 specimens,a total of 12 CFRP plates were fully covered by the adhesive reinforced notched steel plate specimens were stretched.And set up the comparison specimens of unbonded CFRP plate reinforcement,explore the notch size and type of adhesives affect the mechanical properties and stress transfer law of CFRP plate reinforced notched steel plate,etc.(3)Compared with the specimens of CFRP plate fully covered by the adhesive reinforcement notch steel plate at normal temperature,3 kinds of adhesives and 2 types of notch sizes at 55℃,70℃ and 90℃ were carried out.There were 2 specimens in each group,and a total of 36 specimens were statically tested.The study of the influence of temperature on the mechanical properties of CFRP-reinforced notched steel plates provides data support and design basis for the comparison and selection of adhesives in CFRP-reinforced steel structures at high ambient temperature. |
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