Damage Control And Numerical Simulation Of Continuous Beam Bridge Under Seismic Excitation

Bridges serve as transportation hubs, and are important parts of the lifelineengineering. They are of high construction cost and significant engineering meaning.The seismic damage of long span bridges causes great economic loses and greatrehabilitation difficulty. As an important bridge type，continuous beam bridge hasbeen widely adopted worldwide due to its mechanical and economic superiorities. Theresearch in this dissertation focuses on the intelligent control, seismic response anddamage of continuous beam bridge, in which the following aspects are included:(1) A full introduction of the structure, performance, operating modes and outputmodel of magnetorheological (MR) damper based on the control device and controlalgorithm is given at first for better research on the semi-active control and numericalsimulation of continuous beam bridge under the strong earthquake. Then, differencesbetween different control algorithms are compared based on the the equation of state,active control force and the gain relationship between them are summarized.Accordingly, several common semi-active control algorithms based themagnetorheological damper and their physical significance is detailedly expounded,which lays a theoretical foundation for the research on the semi-active control methodand numerical simulation of continuous beam bridge.(2) As for the intelligent control of the continuous beam bridge, most of thecurrent study is aimed at controlling the beam acceleration and the relativedisplacement between pier top and beam with the pier damage is ignored. Animproved semi-active control strategy is proposed against this problem. In thisstrategy, the piers damage parameter is introduced into algorithm of limiting Hrovatoptimal semi-active control, so as to control the seismic response of bridges and thepier’s damage at the same time. Several scenarios of a two-span continuous beambridge equipped with MR dampers is numerically simulated with MATLAB tovalidate the proposed semi-active control strategy. The results indicate that thismethod is well capable of controlling the seismic response and reducing the damageindex of the pier simultaneously.(3) A multi-pier joint semi-active control algorithm is proposed. On the basis ofactive optimal control and with the considerartion of the damage state of the continuous beam bridge pier, this control algorithm adjusts the target output ofdampers, in order to control the acceleration of the beam and the relative displacementbetween the top of each pier and the beam making the damage index of each pieraverage at the same time. A three-span continuous beam bridge equipped with MRdampers is numerically studied with MATLAB and several scenarios are simulated tovalidate the proposed semi-active control algorithm. The results indicate that it is wellcapable of controlling the seismic response and effectively reducing the damage indexof the pier which damage is most serious at the mean time, and achieving the effectthat the damage of each pier is evenly distributed to use this multi-pier jointsemi-active control algorithm.(4) A numerical method of the realization of semi-active control in commercialfinite element software ABAQUS is proposed. The traditional method of numericalsimulation on control theories are realized by programming using MATLAB, which isbased on some assumptions and simplification. However, it is difficult to ensure thatthe seismic response of the structure is always in linear elastic state during the processof hazard evolution under strong earthquake so that certain error during suchsimulation is inevitable. One of the main advantages of the method in this dissertationis that the structural plastic response can be taken into better consideration. Theseismic response of a bridge with three-span continuous girder is numerically studiedand the numerical simulation of semi-active control is successfully realized inABAQUS. The proposed method can be used to carry out the refined simulation ofthe seismic response of the structures with semi-active control set, which provides aneffective approach for the research of intelligent control.