Seismic Response Analysis Of Long-Span Deep-Water Cable-Stayed Bridge In Meizoseismal Area

With the coming of the new era of China’s infrastructure construction, the traffic construction will face special terrain conditions. Particularly, bridges take up a great proportion and it is inevitable that bridges across rivers, oceans or reservoirs will be bulit.The bridges built in these areas will share a common characteristic, the construction of bridge pier in deep water. The impact of accidental seismic load on the bridge should be taken into account in bridge operation stage. When earthquake exerts a force on deep-water bridge, its piers will experience rigid body motion and elastic vibration, thereby affecting the movement of surrounding water. Meanwhile, the water will react on bridge piers in the form of hydro-dynamic pressure. Such kind of mutual influence represents the complex matter of pier-water coupling. Exactly affected by pier-water coupling, dynamic characteristics and seismic response different from those of bridges in the air will be generated, which may exert a negative impact on bridge structure. Therefore, this thesis mainly focuses on simplified methods of observing hydrodynamic pressure and its response to the bridge.This thesis analyzed its hydrodynamic pressure by taking the engineering project of a long-span highway and railway cable-stayed bridge as an example, Specific aspects go as follows:(1) Introduce features of earthquake disaster of bridge structure and further explain earthquake resistance of deep-water pier bridge as well as its research status based on plentiful document literatures at home and aboard.(2) Expound calculating methods of hydrodynamic pressure commonly used in engineering and its basic theories, including Morison equation, radiation wave method and fluid unit method.(3) The calculating method which can consider hydrodynamic pressure of both exterior and interior waters of rectangular hollow bridge pier is introduced in details:Morison equation based on European seismic design codes while considering the expansion of interior and exterior waters; simplified formula based on radiation wave method; hybrid methods based on radiation wave method and fluid unit method. Discuss the distribution characteristics of added mass of hydrodynamic pressure of interior and exterior waters relative to the pier body with the combination of a long-span highway and railway cable-stayed bridge and compare different methods.(4) Analyze the impact of hydrodynamic pressure on dynamic characteristics of bridge structure.(5) Consider the synthesis of seismic waves of spatial variability effects of earthquake ground motions (site effect, traveling wave effect and coherence effect), conduct uniform excitation to deep-water pier long-span cable-stayed bridge and consider the seismic response analyses of multi-support excitation of spatial effect as well as use the hydrodynamic pressure influence coefficient to judge the influence extent of earthquake hydrodynamic pressure on bridges.