EXPERIMENT AND CALCULATION METHOD OF THE DYNAMIC RESPONSE OF DEEP WATER BRIDGE IN EARTHQUAKE

Abstract

AS DEEP-WATER LONG SPAN BRIDGES UNDER EARTHQUAKES, THE INTERACTION BETWEEN FLUID AND STRUCTURE WILL INEVITABLY LEADS TO THE HYDRODY-NAMIC FORCE APPLIED TO THE STRUCTURES. BASED ON THE MORISON POTEN-TIAL FLUID THEORY, A SIMPLIFIED CALCULATION METHOD OF HYDRODYNAMIC FORCE WAS PROPOSED. TAKEN THE NANJING YANGTZE 3RD RIVER BRIDGE IN CHINA AS THE PROTOTYPE, A SHAKING TABLE TEST FOR THE ELEVATED PILE CAPS WAS PERFORMED. AFTER COMPARING THE RESULTS OF THE EXPERIMENT AND THE PROPOSED METHOD, THE ACCURACY AND RELIABILITY OF THE SIMPLIFIED HYDRODYNAMIC FORCE CALCULATION METHOD WERE CONFORMED. THE MAIN CONCLUSIONS INCLUDE: THE NATURAL VIBRATION FREQUENCY OF THE BRIDGE IN DEEP WATER IS DECREASED, AND THE PREDOMINANT FREQUENCY IS REDUCED BY 8.24% DUE TO THE FLUID STRUCTURE INTERACTION. IN EARTHQUAKE, THE EFFECT OF HYDRODYNAMIC FORCE ON THE DYNAMIC RESPONSE OF THE DEEP WATER BRIDGE IS SIGNIFICANT THAT THE BENDING MOMENT OF THE MAIN GIRDER IS INCREASED 7.73% AND THE BOTTOM BENDING MOMENT OF THE MOST ADVERSE PILE IS INCREASED 14.22%. IN THE SEISMIC DESIGN OF DEEP-WATER BRIDGES, THE EFFECT OF FLUID STRUCTURE INTERACTION SHOULD NOT BE IGNORED.