Research On Seismic Control Of Long-span Reinforced Concrete Arch Bridges

Earthquake is one kind of natural disasters with abruptness and severe damage, of which high intensity earthquake can cause a great loss of life and property. In China, areas of seismic intensity 6 or higher spread over every province, where destructive earthquakes happen frequently. During earthquake resistance and disaster relief as well as reconstruction of the disaster area, bridge engineering, as lifeline engineering of traffic engineering, plays a very important role.Long span upper bearing reinforced concrete arch bridge, is one common kind of structure types in western China(especially in southwestern China). However, due to high value of axial compression ratio, it has poor seismic behavior and is unqualified for tradition ductility design. As a result, uneconomical elastic design method is always applied to the design. In this paper, energy dissipation brace device commonly used in building engineering is added to arch bridge, in order to find out one reasonable and economical seismic design method of bridge. In allusion to the installation method of energy dissipation damping brace, earthquake-reduction plan for arch bridge and its effect, this paper conducts some relative research. The finished work as follows:(1) Choice of assessment of seismic behavior. This paper systematically analyses the basical principle of static force method, response spectrum method and time-history analysis method as well as their implement procedures and scope of application. At last, time-history analysis method is selected.(2) Research on the characters of seismic response of arch bridge. Taking the Wei-he-gou arch bridge on Lanzhou-Chongqing Railway as example, this paper creats F.E.M model based on MIDAS to conduct modal analysis and dynamic time-history analysis.(3) Choice of seismic reduction and isolation device. This paper analyses the calculating models and common methods of disposal of viscous energy dissipater, viscoelastic energy dissipater, metal yielding energy dissipater and friction energy dissipation damper. At last, friction energy dissipation damper is selected.(4) Research and exploration on seismic reduction technology of upper bearing arch bridge. Considering the structure characters of arch bridge, this paper provides seismic reduction plan with damper installed on arch bridge. As to upper bearing arch bridge, damper can be used as diagonal brace because of its restrained arch feet. And considering poor seismic behavior of arch bridge, diagonal damper brace can be installed between arch ribs. Engineering example illustrates that these measures above are effective.