Research On Anti-Overturning Stability Of Beam Bridges

As one of the oldest bridge structural systems, beam bridges, which have the characteristic of clear mechanical behavior and could be constructed with mature techniques, are widely applied in urban viaducts and highway bridges. The development of beam bridges shows that engineers and technicians usually focus more on the strength design for structural components, however, they are not sufficiently aware of the lateral stability especially when overloaded vehicles act on beam bridges eccentrically. The inadequacies are shown in inaccurate judging standard and insufficient safety margin about anti-overturning stability of beam bridges in current specifications of highway and urban bridges in our country, and it is also lack of systematical analysis and study for its checking method. In recent years, due to reasons of design and usage, there are many overturning accidents of newly-built and operational bridges, which caused huge economic losses and casualties, and has aroused great concern of the public. In view of the present disadvantages of researches on anti-overturning stability for beam bridges, the characteristics and mechanism of overturning failure, influence factors of anti-overturning stability and a checking method based on lateral anti-overturning stability of beam bridges are studied in this thesis. The main research contents are as follows:1.Summarize the loading characteristics, structural characteristics and failure forms from the overturning cases of beam bridges;2. Analyze the mechanism of overturning failure of beam bridges;3.Analyze the validity of judging standard for overturning failure and checking calculation method for anti-overturning stability of beam bridges and put forward corresponding suggestions for improvement;4. Finite element models for 5 X 23.084m prestressed concrete straight and curved box beam bridges with single column piers are eastablished in order to study the size of overturning risk when the structure is subjected to different loading models and analyze the effects of support spacing to beam width ratio, supporting patterns and curved radius on the anti-overturning stability of beam bridges;5.A checking method based on overturning stability of beam bridges is studied in order to ensure that the overturning failure doesn’t precede strength failure and then some reasonable measures are put forward to prevent the occurrence of overturning failure.