| Steel structures are possibly subjected to extreme load excited by earthquake,explosion and collision, which can result in damages and defects with various degrees.Rehabilitation is in urgent need to ensure the safety of structure and to reduceunnecessary waste of resources. As a new reinforcement material, carbon fiberreinforced polymers(CFRP) composites have been widely used in the civilengineering in recent years, which obtains good economic benefits in practicalengineering. Strengthening with CFRP composites has several advantages, however,interfacial failure between CFRP and steel is one of the most remarkabledisadvantages. CFRP cannot play its excellent material properties due to prematuredebonding, resulting in that the strengthened structure will not work well. Themechanical behavior of interface between CFRP and steel is the most critical issue forCFRP reinforced steel structure. This study focused on interfacial bond behaviorbetween CFRP and steel under static and dynamic loads with bending test. FE modelswere built using general nonlinear FEA software ABAQUS, and simulation resultsshowed good agreement with experimental ones. Specific contents of this study aresummarized as follows:(1) Five specimens with bonded CFRP sheets were tested under static load toinvestigate the influence of thickness and width of CFRP on the interfacial bondbehavior. The failure process and failure modes, characteristics of the straindistribution of CFRP and interfacial stress distribution were studied. Calculationmethod of relative slip considering bending effect was derived. The bond-slip ofinterface between CFRP and steel were simulated using bilinear model, Popovicsmodel and Dimande model.(2) Nineteen specimens with bonded CFRP sheets were tested under impact loadto investigate the influence of impact velocity, thickness, width and bond length ofCFRP on the interfacial bond behavior. The characteristics of strain time history ofCFRP and load-slip were summarized. The strain distribution of CFRP as well asinterfacial stress distribution under impact load was compared with that of static load.Variations of the ultimate load and the mean bond strength under impact load werediscussed.(3) Based on the finite element numerical models verified by experimental results, parameter analysis of influencing factors on load-slip, CFRP straindistribution, interfacial bond stress distribution and effective bond length wasperformed. |
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