The Sensitivity Analysis Of The Deflection To Bridge Damage Of PC Continuous Beam Bridge

PC continuous beam bridge is widely applied in bridge construction due to its advantages of large structural stiffness,good dynamic stability,smooth and comfortable driving,strong bearing capacity and outstanding crossover capacity.However,due to the construction quality problems,the impact of the field environment,long-term overload and other reasons,many bridges in China have appeared the problems of structure cracking and the aging of concrete,etc,which not only affects the appearance of the bridge structure,but also affects the mechanical properties of the bridge structure,or even endangers the operation of the bridge.In order to study the deflection change rules after the aging of concrete and cracking,explore the sensitivity of deflection to beam damage,and master the health condition of bridge,the main bridge of Guanting lake super-large bridge was taken as the research object,the finite element model of the superstructure of PC continuous beam bridge was established by Midas Civil,and the necessary corrections were conducted according to the completion data of the bridge.The main research contents were as follows:Firstly,the influence of gravity load,moving load and temperature load on the deflection of continuous beam under good condition was studied respectively.Then the influence of gravity load,temperature load and moving load under the nondestructive status on the deflection of continuous beam was researched.The sensitivity of deflection to different damage factors was analyzed from three aspects of bending stiffness,shear stiffness and torsion stiffness.Finally,in view of the local damage caused by cracking,the damage conditions of single section and multiple sections were simulated,and the change rules of the deflection of continuous beams were analyzed,and the sensitivity of the deflection to the damage of different beams was investigated.The results showed that,when the PC continuous beam bridge has integral damage,due to the aging of concrete and other reasons,the deflection was more sensitive to the reduction of bending stiffness and the damage degree was greater,and the more obvious the deflection changed,it is less sensitive to decrease of shear stiffness and torsional stiffness.When the PC continuous girder bridge has local damage,due to the box girder cracking,under gravity load,the position of the damaged section would show obvious sharp peak in the deflection distribution curve.Moreover,the damage would have a greater influence on the deflection of adjacent two spans deflection and less effect on other distant spans.Under the vehicle moving load,the sharp peak was also obvious at the damaged position,especially when the mid-span position was damaged;the sharp peak was more conspicuous.It can be seen that the damage status of the beams can be indirectly understood and reference is provided for the bridge inspection,maintenance and reinforcement and operation status evaluation by analyzing the deflection distribution and change rules of PC continuous beam bridge.