Study On Mechanical Properties Of Concrete Structures Reinforced By Paste Method At High Temperature

Structure reinforcement is a measure to implement the national energy-saving andemission-reduction policies. Reinforcement technology of modern paste methodrepresented by the sticking steel and CFRP is widely used, because its applicability isstrong and it is relatively simple to apply. But its fire resistance is poor, reinforcementmaterials have a good fire resistance, the main reason is the structural adhesive. Thestructural adhesive will lose adhesion due to high temperature, and then thereinforcement materials will be out of work.In this experiment, the bond strength degradation of the structural adhesives forbonding CFRP and structural adhesives for bonding steel was systematically analyzedby pull-out tests at room temperature and high temperature cooling. The different heattime and the different heat temperature were considered to test these two structuraladhesives. Finally, we get the two temperature-dependent strength degradation curveand time-dependent strength degradation curve of the two structural adhesives.Base on the pull-out test, the temperature field of12groups concrete specimensreinforced by paste method and coated with different thickness of fire-resistantcoating was analyzed by experiment and finite element analysis software ANSYS inthe fire. The influences of reinforcement materials and fire-retardant coating thicknesson the concrete specimens with thick-layered fire coating for steel structure werestudied. The test and ANSYS proved that the impact of reinforcement material on thetemperature field of the specimens can be ignored, they identified that the best valuesof the fire-retardant coating thickness is40mm, and at this point the specimen fireresistance can reach to2h.It shows that when the temperature is lower than150℃, the structural adhesivescan effectively reduce the deformation of the beam. But when the temperatureexceeds150℃, the deflection is93.2%of unreinforced concrete beam’s deflection, itshows that the role of strengthening has been basically ineffective.