The Influence Of The Input Direction Of Seismic Motion To The Irregular Viaduct' Dynamic Characteristic

The high development of the modernized city must depend on the unimpeded and development of the modernized traffic, and the viaduct of the highway at a high speed of the city and corresponding the grade separation multi-purpose project are the important component of the traffic network of city's modernization. The science of bridge building as one of urban lifeline projects, is destroyed seriously in the earthquake, the enormous difficulty of the disaster relief work, make the secondary disaster aggravate after causing and shaking. Especially to the modernized city, will influence the operation of its production, and cause the enormous economic losses.In recent years, the urban bridge often adopts reinforced concrete curve structure with box shape section, this kind of bridge has a complicated geometry shape, is a non-linear structure system. The domestic and international earthquake disaster indicates, the damage is quite serious to the irregular viaduct when it is in an earthquake, nearly all earthquakes of the past 20 years had caused serious destruction to the irregular viaduct. In view of the above situation, the dynamic characteristic of the urban irregular viaduct and the earthquake resistant design are being paid close attention to by the engineer. However, the earthquake resistant theory of the irregular viaduct and relevant technology are also unripe at present: Especially the mechanics model and analytical method of the urban viaduct under the earthquake action, and the influence of the input direction of seismic motion to the urban irregular viaduct' dynamic characteristic are still needed further investigation and research urgently.For this reason, this text has carried on some analysis and research in the following:Reference relevant documents, this text have studied the structure form, the characteristic of its form and the applicative situation about the domestic and international urban viaduct. Have carried on the discussion on the development and studied the current situation of the earthquake resistant design theory of urban viaduct, have set up the theoretic frame of the earthquake resistant structure system about the irregular viaduct. This article have set up the calculation sketch about the irregular viaduct structure by analyzing the modes of connection and load transfer among the girder, supports, abutments and the function, as well as the distribution characteristic about the rigidity, intensity and quality. It has built up a finite element analysis mode about the curve viaduct with box shape section, using the finite-element method which is the most extensive method being applied in project analysis nowadays. I have calculated the cycle, frequency and shaking modes of the structure, and have carried out the analysis about the dynamic characteristic.The function of the earthquake makes the irregular viaduct in the high coupling working state, the direction of the earthquake motion has important influence with this kind of bridge' nature of earthquake resistant. This article will select the typical seismic wave which is written down by the apparatus to study the input pattern and implementation method about the horizontal earthquake wave input to the structure with one-direction (the horizontal bridge approach, the vertical bridge approach) or two-direction at the same time; this article has studied the influence of the input direction of seismic motion to the urban irregular viaduct' dynamic characteristic using the method which is named by dynamic analysis with time history.According to the analysis and comparison above, I have get some regulation and conclusions, has put forward the design method and suggestion of the irregular viaduct. The achievement of the thesis can offer reference for design and development of the urban irregular viaduct.