Experimental Study On Mechanicsbehaviors Of Reinforced Concrete Beams Under Sustained Load And Corrosion

In the actual engineering,Chloride ion erosion occurs during the loading process of concrete structures. Therefore,consideringthe influence of loading and corrosion on the performance of structure is an important direction of the research of concrete durability. In addition, concrete beams were immersed in chloride solution and by the accelerated corrosion method- "galvanostatic method",corrosion of steel along the circumferential direction is relatively uniform. Because the reinforcement is surrounded by chloride solution, and the resistor of chloride solution is very small, the corrosion reaction of steel surfaceis very uniform, so that along the circumferential direction of the surface of the steel bar corrosion near full corrosion, there are great differences with the actual. The mechanical behavior of reinforced concrete beams in the normal use phase of corroded environment was studied.Experimentalresultsshow that:1. Accelerated corrosion experimental way was conducted on reinforced concrete beams by the constant current-wet and dry cycle. Result shows that the corrosion of steel bar show serious inhomogeneities, Degree of corrosion close to the side of protective layer of concrete is serious than the other, a number of rust pits appear along the longitudinal surface of the steel surface, and the greater the load level, the more serious the corrosion.2. During the period of electric corrosion, by recording the change of mid span deflection of concrete beams under sustained load,the development of deflection of concrete beams under the effect of load and chloride attacks was studied, records showed that: under sustained load of corroded beam Deflection development can be divided into two phases,the initial phase of the beam deflections rapid growth, after the development of deflection tends to be gentle. Third phases will appear in the sustained load of concrete beams BP-60%,the deflection of the beam began to grow rapidly.3. After the corrosion experiment, to measure the crack of the beam bottom. 4 corroded beams were compared, the width of the longitudinal cracks in the bottom of the beam is random, but the general trend is: the greater the continuous load, the greater the width of the crack.. Different load level, the bearing capacity and stiffness of the beam are different.4. After bearing capacity experiment,sampling of beam crack and non-crack area,determination of free chloride ion content in concrete, the data show that: chloride ion content decreases with depth. because of the electric corrosion, the chloride ion accumulated around in the concrete at 25-30 mm. In the same crack depth of chloride ion is higher than non-crack, crack width larger, more obvious increasing trend.