Parameter optimization design of isolated bridge based on improved genetic algorithm

Abstract

It is not uncommon for bridges to be damaged by earthquakes. As an important throat in the transportation network, earthquakes not only cause the loss of bridges themselves, but also cause a series of losses of the transportation network. In the design of bridge seismic isolation, the seismic isolation device is used to isolate the structure from the frequency band where the seismic energy is concentrated and reduce the seismic response of the structure by prolonging the period and increasing the damping. Compared with advanced countries in seismic research, there is a big gap in the research of mechanical model and parameters of seismic isolation devices in China's bridge seismic code. Based on the analysis of the advantages and disadvantages of the finite element sensitivity method and its application limitations, a sequential recurrence method for support optimization is proposed. The results of an example show that the sequential recurrence method has the advantages of strong adaptability and unconditional convergence. On the basis of the sequence recurrence method, the modified sequence recurrence method is further proposed. This method can take into account the influence of the pier inertia force and is applicable to a variety of support forms. After the genetic algorithm optimization calculation, the difference of the bending moment at the bottom of each pier can be controlled within, which solves the problem of large difference of the bending moment at the bottom of the pier under the longitudinal earthquake of irregular bridges.