Experimental Study On Fatigue Properties Of Concrete Beams Reinforced The Damaged Section Increases

Nowadays, with the development of civil engineering construction.Bridges in China is in a steady state.A growing number of scientific workers turning to the management and maintenance has become a bridge. Due to the natural environment and structure their own aging factors, such as reinforced concrete in service period, often appear all sorts of damage, can not meet the design requirement for life.In this paper, based on practical engineering, the enlarged cross section method is adopted in aspects of design of experiment, systematic study and analysis of simplysupported reinforced concrete bridge, the fatigue performance of the reinforced design the related experimental study on the scheme. To damage of reinforced concrete beam and steel bar stress level under different load as the research object, adopt the method of increasing the cross section of reinforced concrete beams reinforcement, and the fatigue test, cyclic loading is analyzed under the action of reinforcement beam fatigue performance. Mainly studied the following aspects:① Studied the use of reinforced concrete beam section enlargement of the mechanical properties and failure modes. Three sets of experiments were designed to carry out comparative analysis of the specimen, the first set of specimens Total two beams, one has not been directly reinforced static load test to get the original beams to guide the test ultimate bearing capacity of the damaged beam load(approximately ultimate load of 0.85 times), in addition to a reinforcement after the static load test to reinforce rear beam measured ultimate bearing capacity,fatigue test guide beams loaded at the same time get the static performance of reinforced concrete beams after.②The effect of load level fatigue cycle fatigue properties of reinforced concrete beams. The second set of specimens Total 3 beams, not damaged before strengthening treatment for fatigue testing. Lower limit of fatigue loading unity 0.1, the upper limit were taken 0.5, 0.7 and 0.9. Research under different stress conditions, strengthening the fatigue properties of the beam.③ Study the impact on pre-damaged section enlargement fatigue behavior of reinforced concrete beams. The third set of experiments altogether two beams. Two beams according to 0.85 before strengthening damage done deal, then the fatigue test, fatigue test load level and after the second set of two identical beams in comparison to study the effects of fatigue on performance reinforcement beams early pre-injury behavior.④Combined with experimental data obtained by linear fitting cyclic loading under section curve increases reinforced concrete beams, as predicted by increased life expectancy reinforced section of the bridge structure was provided.⑤The mechanism of fatigue damage accumulation is discussed. On the basis of the use of the residual stiffness test data and theoretical analysis method for increasing the beam cross-section of damaged concrete test Reinforcing analyzed validated structural fatigue damage has been the law of development of the whole process in three stages.