Thesis or Dissertation Seismic performance of curved highway bridges with steel bearings under serious earthquakes

田, 欽

As urban areas have become more congested and highway interchanges have become more complex, horizontally curved composite steel I girder bridges have become an essential component in highway infrastructure. These types of bridges are key to providing smooth transitions from one highway to the next, allowing for a seamless flow of traffic. Unfortunately, bridges with curved configurations may sustain severe damage owing to rotation of the superstructure or displacement towards the outside of the curve due to the complex vibrations that occur during serious earthquakes. So how to improve the seismic behavior of curved viaduct becomes important during strong earthquakes. Stopper installed at both sides of roller bearing in tangential direction, cable restrainer equipped between adjacent superstructures, viscous damper installed at expansion joint and shock absorber device set between roller bearing and stopper are all evaluated respectively in this thesis. Traditional steel bearings are very common, but they are easy to be broken in earthquakes. Recently roller bearings equipped with stopper are installed on top of piers. Because stopper can be easily installed and the price is not expensive, so it has wide application prospect in future. Therefore, the effect of stopper together with cable restrainer on mitigating curved viaduct damage during serious earthquake is carried out. The relationship between different stopper values and the different types of damages is obtained. The advice for the seismic design of viaduct based on the appropriate stopper values has been put forward. Recently, cable restrainer installed at curved viaduct can significantly reduce the possibility of deck unseating damage. In this thesis, the effect of stiffness and slack value of cable restrainer on curved viaduct damage is presented. According to the evaluation results, the seismic design of curved viaduct based on the cable restrainer with appropriate stiffness and slack value can be put forward. In addition, a comparison between restrained and unrestrained curved viaduct is also presented. Finally, the use of cable restrainer reducing curved viaduct damage is proved in this thesis. In addition, application of viscous dampers to viaducts has gained significant attention in recent years. Due to its large resistance force and energy dissipation capacity, viscous dampers have wide application prospect. The most advantage of viscous dampers is that it shows no resistance forces under slow relative movements of segments results from thermal changes, creep and shrinkage effects. It is only activated when earthquake happens. Therefore, this thesis analyzes the overall performance of highway viaducts with different kinds of viscous dampers and different stopper values. Different kinds of viscous dampers have different stiffness and different resistance forces. So the relationships between different kinds of viscous dampers, different stopper values, and curved viaduct damage have been found respectively. A comparison between curved viaducts equipped with viscous dampers and without viscous dampers is also carried out. The calculation results demonstrated that stopper value plays a more important role in piers damage than viscous damper. In recent years, the effects of shock absorber devices installed between adjacent viaduct segments on reducing pounding forces, have been studied by many researchers. But the effectiveness of shock absorber devices installed between roller bearing and stopper on reducing pounding damage, is lack. In this thesis, calculation results clearly show that the curved viaduct with shock absorber devices between roller bearing and stopper present less damage. In addition, the effect of stiffness and thickness of shock absorber devices on mitigating curved viaduct damage is evaluated respectively. Besides, strain hardening, strain softening and elastic shock absorber devices are also analyzed in this thesis. Conclusively, shock absorber devices with large stiffness and large thickness present less viaduct damage. Curved viaduct with strain softening shock absorber devices exhibits less viaduct damage.
viii, 114
Hokkaido University(北海道大学). 博士(工学)

Number of accesses :  

Other information