Anti-overturning Analysis Of Continuous Beam Bridge With High Single Pier

With the rapid development of China’s urban transportation,urban viaducts and flyovers become more and more common in daily life.Among which,continuous beam bridge with single pier is widely used in urban flyovers and ramp bridges for its lovely appearance,lesser covered area,reasonable spatial arrangement,etc.However,controlled by the small diameter of the pier,single pier continuous beam bridge has a much more lesser anti-overturn ability,comparing with other forms of continuous beam bridge.Meanwhile,the large population of people and automobile won’t decrease to a lower standard in China in a short term,which makes it more universal that bridges are fully covered by heavy cars or even overweighted cars.Based on the above situation,referring to the relevant information,this paper summarizes the possible failure forms of the superstructure overturning,and extracts the overturning effect vector reflecting the superstructure overturning mode,including the quantitative expression of the overall overturning,the local stress state of the support,the sliding condition of the superstructure and the inclination angle of the superstructure.Based on this vector,the expressions of overturning effect and anti-overturning effect of each overturning mode item are derived mathematically,and a relatively complete anti overturning calculation system is formed.Taking the south approach of Hechuan Qujiang bridge as a reference,combined with the finite element numerical simulation data obtained by using MIDAS/Civil software to model the main beam and ANSYS software to model the support details,this paper calculates the single column pier continuous beam bridge under different curvature radius and support spacing.According to the relationship between each overturning mode item and eccentric load and the critical failure load of each item,the correlation of each factor in the overturning effect vector is discussed.The influence of curvature radius,support spacing,pier height and support strength on the anti-overturning stability of the structure is obtained,and the overturning form of the superstructure under the influence of multiple factors is described,It is pointed out that the overall overturning and bearing extrusion are the controlling factors of superstructure overturning.When the bearing strength is insufficient,the critical load of failure will be greatly reduced.This paper puts forward some suggestions on the design of superstructure and support arrangement,and demonstrates the rationality of using point hinge support in the middle span of curved girder bridge from the angle of overturning effect vector.This paper also makes a comparative analysis of the anti-overturning bearing capacity of single column pier continuous beam bridge based on overturning effect vector and the current code mode,which shows that the current code requirements that the bearing cannot appear void waste the anti-overturning capacity of superstructure.At the same time,it is pointed out that the stability coefficient method based on the rigid body rotation theory is only a partial calculation of the overturning effect vector in the current code method,and it is unreasonable and dangerous to use this method without considering other.overturning modes.