Study On Seismic Design Of Composite Foundation Of Span Continuous Rigid Frame Bridge

In recent years, with the accelerated process of urbanization and rapiddevelopment of transportation construction business, a large number of bridges inchina is built. Bridges are not only as an important social infrastructure, but also thelifeline project. When the earthquake happened, once the buildings were destroyed,not only will give the people a huge loss of life and property, and interrupt the arteriesof the transport of materials, bringing enormous difficulties to earthquake relief. In2008,8.0grade earthquakes occurred at Wenchuan in China, Tens of thousands ofpeople lost their lives, a large number of buildings were severely damaged, causinghuge losses to the country.Therefore, the engineering staff and experts and scholars pay more and moreattention to the seismic design of bridges. Vibration isolated measures to be taken toreduce the bridge suffered damage in the earthquake became the focus of attention.Continuous Rigid Frame bridges is widely used because of its shape and lightappearance, structure stiffness and small deformation, material savings and lowercost.Preliminary Experiment on basic damping was studied in this article. A typicalContinuous Rigid Frame bridge was used as an example. According to the latest issuedesign guideline of highway bridges seismic, structural characteristics of the bridgeand the bridge seismic response were analyzed by response spectrum method and timehistory analysis method. Primarily work and achievements of this paper is as follows:①It was the first time a loop isolation belt around the bridge pile foundationwas proposed to achieve the effect of isolated energy consumption. The silt, butterand earth, tung oil and soil and rice and lime soil, gypsum powder and soil wereselected for replacement materials. Replacement filling materials around the pilefoundation and their relevant characteristics are described also.②Produced piers and pile foundation model, replaced the soil around the pilefoundation, and did the dynamic test of the model using related equipment andfacilities, obtained the dynamic response on the top of the pile and the bottom of thepile with different backfilling materials, including displacement time histories andstress-strain of pile foundation. Finally, combining glutinous rice and lime soil asfilling material achieved the best damping effect. ③Take an real rigid frame bridge as an example. Build up the whole bridgecalculating model by the large finite analysis software MIDAS. Natural vibrationcharacteristics of the bridge were analyzed.④The response spectrum were analyzed under different working conditionsprovided by the seismic detailed rules. The seismic waves of MIDAS/CIVILsoftware were adapted to analysis response spectrum.⑤The seismic characteristics of original structure and of the new structure werestudied by dynamic time history analysis method using waves of MIDAS/CIVIL. Itreveals that better effect of damping will obtained when pile foundation stiffness ofnew type structure was taken as0.75-0.9times of the original stiffness.