Experimental Study On Fatigue Performance Of Concrete Beams With Stainless Steel Bars In Bridge

In recent years, there are many applications of stainless steel reinforcement in foreign countries especially on bridge engineering due to its superior corrosion resistance and mechanical properties in reinforced concrete. So far the research of stainless steel reinforced concrete is almost concentrated in the material properties of stainless steel, concrete, corrosion resistance and mechanical properties.But the research for fatigue properties of concrete structural element reinforced with stainless steel is still few. The text researches stressed fatigue properties of concrete beam reinforced with stainless steel.Based on the tests of seven concrete beams reinforced with stainless steel and two ordinary reinforced concrete beams, the text researches the crack width、the relationship between stress-strain of concrete and reinforced. The text is discusses the influence with crack、deflection and fatigue life by the different types of reinforced、different stress levels and reinforcement ratio. The concrete beams reinforced with stainless steel can be met the limit of the fatigue properties in code for design of concrete structures.Based on comparison of the results of the experiment, this paper analyze the impact of the different materials, stress level and reinforcement ratio, the fatigue properties of the beams.Fitting the S-N curve as the the analysis is based on the fatigue life.Testing main conclusions are as follows:1. Under the same stress level and reinforcement ratio condition, with the comparison of reinforced concrete beam specimen, the accumulation of residual strain of the stainless steel reinforced concrete beam concrete are decreased by76.1～83.8%, the strain of concrete reduced by12.5～42.5%, the tensile longitudinal reinforcement of residual strain reduces9～20.4%, across the largest deflection decreases6～9%. Compared with ordinary reinforced concrete beam specimen, stainless steel reinforced concrete beam and reinforced concrete specimen of cumulative damage are less.2. Under the effect of different stress level, the stainless steel reinforced concrete beam specimen with the increase of0.05Mu, the residual deflection of beam is increased by% ～18.5%, and load-deflection increased7～22%, the stiffness reduction coefficient reduced by5～9.9%, the deflection and the crack development are more rapidly, crack expansion is more apparent, the beam stiffness degradation is faster.3.With stainless steel reinforced concrete beam reinforcement ratio of the specimen decreased to0.82%from1.07%, the stiffness reduction coefficient of stainless steel reinforced concrete beam specimen decreases4.5～6.2%; With the decreasing of stainless steel reinforcement ratio from0.82%to0.6%, the stiffness reduction coefficient reduced by2.4-4.4%. Lower beam reinforcement ratio, With the increase of the reinforcement ratio, the load deflection and residual deflection of stainless steel reinforced concrete beam are decreased, the development of crack is slow, the gap width is smaller, the stiffness degradation is slow.4. Though the test by stainless steel reinforced concrete beam under different stress level, the fatigue life of S-N curve is draw, and obtain the formula expression for1gN=25.1365-4.45121g△σ. With the comparison of reinforced concrete beam specimen, the corresponding cycle number of stainless steel reinforced concrete beam specimen increased from21.1%to27.3%under the same stress level and reinforcement ratio and the same stress amplitude corresponding.