| Textile reinforced concrete(Textile reinforced concrete,TRC)has excellent ability of bearing capacity,delaying crack and corrosion resistance,suitable for the repair and reinforcement of concrete structure in harsh marine environments.Due to these advantages of TRC,it will have wide application prospect in building structure.At present,there are already many researches on the mechanical properties of concrete structures strengthened with TRC under conventional conditions,however,there are few studies on the mechanical properties and durability under corrosion environment,especially in the sustained load condition,which has not been reported publicly.This will limit the application of TRC in the future.In this paper,under the environment of chloride dry-wet cycles,the flexural behavior of reinforced concrete beams(reinforced concrete,RC),having no load-bearing or load-brearing when they were strengthened with TRC,was studied.For beams which there were no load-bearing when they were strengthened with TRC,the effects of the chloride wet-dry cycles and the coupling effect of chloride wet-dry cycles and sustained bending stress on the flexural properties of RC beams were considered.For beams which there were load-bearing when they were strengthened with TRC,the effects of the load-bearing stress at enhancement,the reinforcement way,the type of textile,the addition amount of short fibers,salt concentration,the chloride wet-dry cycles and the coupling effect of chloride wet-dry cycles and sustained bending stress on the flexural properties of RC beams were considered.Finally,based on the experimental results,the theoretical calculation formula for the analysis and calculation of RC beams strengthened with TRC under chloride condition were given.For beams which there were no load-bearing when they were strengthened with TRC,the results show that the maximum crack width and mid-span deflection of beams increase,and the cracking load,yield load and ultimate load decrease with the increase of the dry-wet cycles;the maximum crack width increases,and the yield load and ultimate load decrease with the increase of the sustained bending stress under chloride corrosion.When the sustained bending stress is 0.5,the maximum crack width and ultimate load declines significantly.Due to the influence of initial deflection under sustained stress corrison,the deflection of these beams is smaller at the same load.For beams which there were load-bearing when they were strengthened with TRC,the results show that TRC’s reinforcement can play a good role,the crack width and deflection of beams are improved,the bearing capacity is enhanced when the load-bearing stress is 0.2 and 0.4 at reinforcement;howere,the change of the failure mode of the beam causes the overall performance of the beam to be greatly reduced when the load-bearing stress is 0.6.For the beams strengthened with the precast TRC plate,their faiure modes are slightly different with those of the beams strengthened with cast-in-place TRC,but this is almost the same at improving bearing capacity and controlling the deflection,and thus precast TRC can also be applied to practical engineering.The TRC made of carbon textile is superior to the TRC made of the basalt textile in improving the bearing capacity of TRC-strengthened beams.Reinforcement effect of the beam has been improved due to adding short fibers into fine-grained concrete.The crack width and deflection of the beams increase,and the bearing capacity of the beam decrease with the increase of the salt concentration and the number of wet-dry cycles;the ultimate bearing capacity of the beam decreases and maximum crack width increases with the increase of the sustained bending stress,but the crack width and deflection of the beam are better controlled before steel bars yield.Based on the limit analysis theory and experimental results,the formula of ultimate bearing capacity of concrete beams strengthened with TRC is presented,and the calculated results are in good agreement with the experimental results. |
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