| The melting ice flood is peculiar hydrological phenomena in the river in the winter freeze area. The Inner Mongolia reach of the Yellow River is one reach of the most serious the Yellow River melting ice flood reach, the Yellow River melting ice flood strike on the long-span bridges, which produced the responses of the bridge and the influence on the safety of the bridges, all of that must be considered in bridge engineering design, construction and operation process.Combining with parts of the Inner Mongolia autonomous region transportation science and technology project "the research on Baoshu Yellow River super major bridge frozen and melting ice flood action and the processing measures", related research is developed in this paper. started from the basic characteristics of the Inner Mongolia autonomous region reach melting ice flood, combined with the practical engineering, the Inner Mongolia reach bridge design ice pressure calculation formula and method is discussed, the finite element model of the whole bridge is built, the static and dynamic safety analysis and research of Baoshu Yellow River super major bridge during the melting ice flood is carried out, which can provide the basis for the melting ice flood defense design of Yellow River bridges.Firstly, make Baoshu Yellow River super major bridge as the research object, the impact force caused by the big quality melting ice strike on the long-span bridges is practical measured in the engineering field. Pressure sensor installed on the melting ice strike on ice apron position, collected the ice pressure signal while melting ice flood strike on the bridge piers or cushioncap, collection and analysis of the impact force signal while melting ice flood strike on the bridge piers or cushioncap using the collection and analysis instrument, put the analyze results into the computer, then the impact force practical measurement of the ice load on bridge piers or cushioncap during the melting ice flood period is obtained.Secondly, through the collection and research on relevant data of meteorological, hydrology, melting ice flood on domestic and foreign and Yellow River bridge area, observant the melting ice flood morphology (including volume, velocity, etc.) during the melting ice flood period, then analyzes the effects on the melting ice flood by the sun radiate heat, water temperature, wind, annual rainfall, the humidity in the air, water level, the change of flow velocity, the channel, etc. considering the main factors of the melting ice flood size, the ice pressure calculation formulas suitable for the Yellow River Inner Mongolia autonomous region ice condition is put forward make use of kinetic energy and kinetic energy principle, and comprehensively considered influence coefficients of the melting ice strength, ice temperature, local extrusion, contact points conditions, ice thickness, pile column shape, pile column meet ice plane area, etc. Compared with the calculated results using each ice pressure calculation formulas at home and abroad separately, especially compared with results using the 2004 highway bridge design standard calculation formulas, thus validated the accuracy and applicability of the calculation formulas in this paper.Thirdly, using the finite element software "MIDAS" for the whole bridge structure simulation, Baoshu Yellow River super major bridge the whole bridge three-dimension finite element model is established, including simulation of continuous girder bridge bearings, pile-soil interaction, the common reinforced concrete and phase ii constant load. Bridge structure static characteristics are studied under melting ice flood period the most unfavorable load combination action. Through analysis of Baoshu Yellow River super major bridge main bridge the whole bridge finite element model in operation stage, static calculation and analysis under melting ice flood period the most unfavorable load combination action, to check the whole bridge structure strength and rigidity.Finally, using established Baoshu Yellow River super major bridge the whole bridge three-dimension finite element model, vibration characteristics of the bridge structure in a horizontal load is studied. At the same time, through calculation and analysis of the whole bridge structure finite element model, the dynamic response analysis of the main bridge in melting ice flood period in the big quality ice and mass flow melting ice respectively is carried out. The bridges temporary dynamic security evaluated using the calculation results. At the same time, ice load simulation using melting ice load reaction spectrum theory put forward in this paper is verified, and proved that ice load simulation using this theory is accurate and reasonable. |
