Analysis On Seismic Response Characteristics Of Skewed Box-Girder Bridge

As a type of a commonly used simple and special bridge, the skewed box-girder bridge is always used as overcrossings in highway intersections and interchanges. The previous seismic damages have revealed that the skewed box-girder bridges are more susceptible than straight box-girder bridges with regular geometry to seismic damage, and the mechanism of fracture is more complex than straight box-girder bridges. The rotation of the bridge panels and collision effect are the main factors to influence the seismic characteristics of the skewed box-girder bridge. Therefore, it is necessary to realize the dynamic properties of the skewed box-girder bridge that under the effects of the earthquake. The main contents of this thesis are as follows:1. It has discussed the present research achievements of home and abroad. Observing that the shear force and displacement of the simply-supported skewed box-girder bridge will change with the input direction of the ground motion, it introduced the theoretical calculation method to identify the most unfavorable earthquake input direction, and applied this method to the two span skewed box-girder bridges. Through the comparative analysis, it reveals that the influence extent to the reaction of this bridge affected by the input direction of the ground motion. When skewness changes, the influence extent changes.2. Combining the damage phenomenon of the skewed box-girder bridge, it has modeled the finite element models of the two span skewed box-girder bridges which considered the collision effect between the girders and the abutments, analyzed the parameters that influence the longitudinal collision effects and then analyzed the response of the piers contrastively. It reveals that longitudinal collision effect can't be neglected in seismic design, because the longitudinal collision may greatly increase the largest bending moment of the piers.3. It has modeled the finite element models of the two span skewed box-girder bridges that considered the impact effect between the girders and the seismic blocks, analyzed the parameters that influence the transverse impact effect, and then analyzed the response of the piers contrastively. It reveals that the choosing of the distance between the girders and the blocks will influence the results of the transverse impact greatly.4. It has compared the interrelation between the transverse impact and the longitudinal impact, revealing that the transverse impact will reduce the longitudinal impact. Similarly, the longitudinal impact will reduce the transverse impact and the influence extent changes with the skewness.