Experimental Study On Fatigue Behavior Of Prestressed Concrete Bridge Under Heavy Load Traffic

Nowadays the volume of load traffic is increasing in our country, transportation vehicles are becoming increasingly both heavy and large. Due to the economic benefits, the overload phenomenon in highway transportation is very serious. In recent years, The accident of bridge collapse in our country are mostly caused by overloading of vehicles. Therefore, the fatigue problems of bridges caused by heavy-load or overload have been widely concerned. This paper take 16 m prestressed concrete slab beam as the prototype. Based on the similarity theory and produced 7 pre tensioned prestressed concrete model beam by the 1/4 scale. Through the indoor fatigue experiment, the fatigue performance of prestressed concrete beams under heavy load is studied. The main research works are as follows:1) The cracking load and the ultimate load values are obtained by static load experiment of 2 beams.2) Based on the constant amplitude fatigue experiment of 5 model beams under different fatigue upper limit load and same fatigue lower limit load, Get their fatigue life values and analysis on the fatigue failure mode and the changing rule of strain of concrete, the strain of steel bar and prestressing tendon bar, crack width, deflection and stiffness with the increasing of fatigue loading times under the action of heavy load.3) According to the dynamic strain data from the fatigue experiment of each model beams, calculate the reinforced stress amplitude Δσ and obtain the fatigue life N that when the residual crack width reached 0.2mm by the experiment data. Then, fitting out the S-N curve equation of beam model: lg N =15.071- 4.612 lg Δσ...