Durability Of Overload Damaged RC T-Beams Subject To Hygrothermal Environment

With the rapid development of transportation in China, the number and proportion of a variety of heavy-duty trucks, large flatbed truck, container trucks, etc. increases every year, and some transport units and unauthorized modification of vehicles, so that the overload is a common phenomenon, and the damage of roads and bridges is very serious, in some extreme cases, it can cause a catastrophic accident. The cracks and large deformation damage that can’t be recovered caused by the overloaded vehicles, not only reduces the load carrying capacity and stiffness of the main beams, but also makes the main beams to be corroded easier by environment. In this paper, the effects of overloading and humid environment on the durability of reinforced concrete T-beam was studied for overloaded highway reinforced concrete bridges in hot and humid environment in southern China. The main research work and conclusions are as follows:1、In this paper, combined with the overload vehicles data collected by the sensor called "weighing system" on the Guangzhou Beltway, statistics the traffic and load in each lane on the typical beltway of Guangzhou in recent years, combined carrying capacity of small and medium-span bridge, to get a random vehicle overloading spectrum in southern China. Combined the classic S-N curve and the "Miner linear cumulative damage theory" calculate the random vehicle overloading spectrum. And then we can get a amplitude overloading vehicle spectrum.2、In the paper the beams after overloading damage were tested to study the bending capacity of RC T-beams after overloading damage. The specimen deflection, cracks and flexural capacity of overload damage were analyzed. The amplitude overload vehicles spectrum was loaded into reinforced concrete beams. Simulated overload damage to the bridge. The results show that the RC T-beams after overloading damage have lmm length residual deformation and0.04mm length cracks, the damage concrete can’t decreased the bending capacity of RC T-beam, but as a result of the steel bar in test beam after repeated stress will produce a certain effect of cold-drawing, the strength of RC T-beams after overloading damage increased slightly with an average increase of7.6%. But the ductility significantly decreased with the average decline of33.5%.3、In this article, Overloading damaged beams after wet and dry cycle test are tested to study the effects of wet and dry cycles on overloading damaged reinforced concrete T-beams and analyzed the flexural strength and ductility of the test beams. Because of cracks, the chloride ion in the solution is easier to enter into the concrete, there is a certain corrosive effect on the reinforced. The results show that the wet and dry cycle makes the carrying capacity of the bearing of the structural lower than the overloading damaged structure with a decline of3.6%, but still higher than the carrying capacity of undamaged concrete beams with the increase rate of3.7%. However, the ductility continues to decrease with the rate of47.1%.