What Is Seismic Analysis?

With the development of urban transportation in China, many large and complex interchanges and viaducts have been built in many cities. Among them, most urban interchanges and viaducts are located in areas with an earthquake intensity of more than 7 degrees and must be designed for earthquake resistance. However, China's current seismic design specifications for railway engineering and highway engineering seismic design have many shortcomings due to their long history. Moreover, it is mainly applicable only to standard bridges, such as for the design of complex interchanges and viaducts, and it is difficult to ensure the seismic safety of the structure. Most foreign bridge engineering seismic codes are also only applicable to standard bridges with medium spans, but most seismic design codes have pointed out that for complex bridges, dynamic time-history analysis is required for special seismic design.

Seismic response analysis

Right!

With the development of urban transportation in China, many large-scale complex interchanges and

Since 1943 Biot proposes

Calculation model of orbital structure system for seismic response analysis

When the lower layer of a light rail viaduct or double-layer viaduct is rail transit, the influence of rails and rail fasteners should be considered. On the one hand, due to the restraining effect of the rail on the bridge, the vibration frequency of the bridge is increased; on the other hand, under the action of longitudinal earthquakes, relative sliding between the bridge and the rail will occur, and the relative sliding between the beam and the rail is hysteretic Can dissipate some seismic energy.

Basic assumptions for seismic response analysis

The seamless long steel rail is regarded as a space beam unit;

Does not consider beam-rail interaction caused by temperature changes, vertical loads when there is a car, and braking force;

The integral track bed, sleeper (or bearing platform) is cast into the main beam as a whole, and it is considered as a whole with the main beam. The beam and rail are connected by a fastener unit, which can be regarded as a two-node composite spring unit.