Evaluation Method Aseismic Capacity Of Cable-Stayed Bridge With Steel Box Girder

The development trend of modern long-span cable-stayed bridge is cable-stayed bridge with steel box girder. Therefore, to carry out the research of aseismic capability assessment method and earthquake damage evaluation, is of great significance for the structure of this kind of bridge seismic design and post-disaster damage evaluation and reinforcement.Based on the concept of the structural yield strength and ductility of the seismic assessment, according to the failure mode of different structures, this paper conducts research on the calculation of the failure strength and ductility of the small earthquake response. Surrounding structure aseismic ability of calculation and seismic damage of the earthquake damage evaluation, the aseismic capability assessment for cable-stayed bridge with steel box girder, the seismic capability assessment method of cable-stayed bridge with steel box girder is proposed. The content of the paper is as follows:1. The yield strength calculation of the structure primarily is on the basis of the current specification, and the ductility calculation of the structure is on the basis of the mechanics performance index. In the calculation, the strength calculation formula of reinforced concrete box section and the ductility calculation formula of steel box girder, pile group foundation and bearing have been deduced reasonably. In the process of solving the problem of structural ductility, the ductility of steel box girder parts is the ratio of ultimate bending moment and yield moment under the action of pure bending. As for the basic parts, the ductility of the most adverse single pile is the ductility of the whole basic parts.The ductility of the bearing parts is the ratio of ultimate displacement and yield displacement for shear deformation of rubber.2. The cable-stayed bridge with steel box girder aseismic capacity evaluation method is:first, calculated the internal force of structure using finite element software under the short-term effects S and small earthquakes (0.05g) of destroying the acceleration coefficient a, then according to the component of ductility capacity calculating allowable ductility capacity Ra, and earthquake force reduction factor Fu which is based on the natural vibration period, site type of the structure system. Finally, by the destruction of acceleration coefficient factor a, earthquake force reduction factor Fu and under the action of small ground motion acceleration ag, the maximum acceleration of ground motion Ac is obtained which each component can resist. The smallest Ac that is weighted calculated and integrated in each component is as aseismic capacity of cable-stayed bridge with steel box girder.3. Using variable weight comprehensive analytic hierarchy process (AHP) to calculate weight of the cable-stayed bridge with steel box girder’ components and the whole bridge seismic damage index and referring to the failure criterion of aseismic structure and the characteristics of the aseismic capability assessment method in this paper, the damage model of cable-stayed bridge with steel box girder is put forward. According to "China’s seismic intensity table"(GB/T17742-2008), evaluation criteria of cable-stayed bridge with steel box girder earthquake damage is put forward. The structure’s seismic weak point and extent of damage can effectively be found by the assessment of seismic capacity and earthquake damage.4. To evaluate the aseismic capacity of a cable-stayed bridge with steel box girder. The results showed that:the evaluation method in this paper is simple but feasible. It can quantitatively evaluate the aseismatic capacity of the bridge and qualitatively analyze the seismic damage of bridge.