| Nowadays, bridges cannot meet the served safety requirement because of corrosion of steel bar which restricted the operation of bridges, therefore, they should be taken measures to repair and reinforce.In order to study corrosion reinforced concrete beam by bolting and affixing steel plate at the bottom, 12 reinforced concrete beams are designed to analysis the bearing performance of these beams after strengthening in different thickness of steel plate and different thickness of concrete cover.(1) 12 beams are corroded by using accelerated electrochemical corrosion method.The pre-compression expertments are performed for all RC beams before strengthening and the maximum crack width is controlled as 0.2 mm. According to the thickness of concrete cover, the beams are divided into 3 groups.Each group is composed of one comparative beam and three tested beams strengthened by steel plates bolted with stud according to the thickness of steel plates which are 3mm, 4mm and 5mm.(2) Strengthened corrosion RC beams are tested by using the single-point load method, and the experimental data is recorded at the same time. Through the analysis of these data, it is said that the strain distributions along the height of the strengthened beams at middle-span are in good agreement with the plain section assumption basically. The serviceability performances of corroded RC beams are significantly improved and thses ultimate bearing capacities increase obviously. The steel plate bolted with stud effectievely reduces the crack width and the extension height of reinforced concrete beams. It is indicated that an increase of steel plates with 3~5mm resulted in a decrease of deflection when beams have the same thickness of concrete cover and corrosion ratio. Influence of the thickness of concrete cover on the ultimate bearing capacity is not obvious.(3) Based on the experimental results and the bearing capacity calculation theory of RC beams, the formula of flexural strengthening RC beams by bolting and affixing steel plates is given in this paper and the comparation between tested results and the theoretical results indicates that the formula provides a good reliability.(4) Based on the tested results, this paper analyzes and calculates the time-dependent reliability of reinforced concrete structure combined with an example, and simulates the degradation of RC beams' reliability index before strengthening and after strengthening. It is shown that the calculation results and the experimental conclusions fit well through analyzing the effect of different factors on the reliability. According to these results, it verifies the reliability of the method of strengthening by steel plate anchored with stud and the correctness of the experiment. |
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