Taking the through-type tied arch bridge with a span of 144m as the research object, the working principle of the friction pendulum bearing is introduced; through the finite element simulation analysis, the seismic performance of the Yunnan Nujiang Dukou Bridge is studied, and the seismic safety evaluation is used to give. The three seismic wave time-acceleration time-history curves are respectively analyzed for the seismic performance of the through-type tied arch bridge when the friction pendulum vibration isolation support and the ordinary steel spherical hinge support are used. The research results show that the use of friction pendulum damping and isolation bearings can delay the vibration response of the superstructure from the seismic excitation, thereby achieving the effect of prolonging the vibration period of the structure and reducing the possibility of resonance of the structure under the action of an earthquake. At the same time, when the friction pendulum support swings back and forth, part of the seismic energy can be consumed by the friction between the wear plates. Compared with ordinary steel spherical hinge bearings, the use of friction pendulum vibration isolation bearings can make the piers of the arch bridge participate in the earthquake resistance together, and the internal force distribution of the piers is also more uniform. However, the horizontal displacement of the pier beams increases significantly, and corresponding protection needs to be taken.
Jun Xu, born 1978, received his MS degree from South West Jiaotong University. He has been involved in bridge design and inspection for 12 years.
SummarySince 1980s China has forged more than one hundred cable-stayed bridges. With the passage of time, the stay cables of many bridges have been gravely corroded and some of them were broken causing collapses. In the grim situation, apprehensions about the safety of these cable-stayed bridges arise. This paper advances a series of pragmatic methods to attack inspection and evaluation of parallel wire cables. First of all,a grading contrast standard for corrosive wires is established for the convenience of visual inspection. Inspections are then carried out on cables dismantled from cable-stayed bridges to find out the distributing rule of internal corrosion. Furthermore, a single wire modelling is built based on wire deterioration mechanism. It is required that the modelling should consider the dual influences of corrosion (including homogenous corrosion and rust pit etc.) and fatigue, which can be adjusted through testing. On the basis of the single wire modelling, a parallel cable model can be applied to figuring out remaining bearing capacity and forecasting remaining service lives of the cables. Finally, the experimental values of the discarded cables are compared with theoretical ones to verify the precision of the theoretical analysis. The method proposed in the paper was once applied to the inspection and evaluation of Shimen Bridge to determine the first replacement of stay cables. In the evaluation, the remaining service lives of the remaining cables were successfully estimated.
The environmental factors have complex effects on the bearing properties of group pile foundation. Based on the "growth" process of the Sutong Bridge and the combination characteristics of environment factors, the relationships between the measured values of the group pile foundation and environmental factors were established. Then, the correlation decision determinations between the measured values and environmental factors were obtained by using the Bayes estimation fusion algorithm. Finally, the impacts of different environment factors on the bearing properties of group pile foundation had been got. The results showed that the impact of seasonal temperatures on the mechanical performances of the group pile foundation is very large.
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