The Analysis Of Unseating Prevention Devices Considering The Excitation Of Strong Earthquake Sequence

Unseating prevention devices are the ultimate security installment in the collapse-proof system when the highway bridges encounter rare earthquake or unexpected earthquake. Based on the relational design standards at home and abroad, the paper has design the cable-unseating prevention devices for the structure, and then time-history analysis has been carried on under rare earthquake and strong earthquake sequence.Through analysis and calculation, the variation law that pressure of unseating prevention devices and effect of collapse-proof changed with cable length and design moving value has obtained, which guide the design of the corresponding optimal unseating prevention devices. As the 1.5 times of constant force design method cannot gratify the seismic requirements when bridge under the rare earthquake excitation, the paper proposes the 3 times of constant force design method to replace. Under the rare earthquake excitation, unseating prevention devices can not only preventing the beam from falling down the substructure but also increasing the integrity and anti-pushing rigidity of the structure. The rational unseating played the very good role under strong earthquake sequence, improved the Seismic Performance of structure and provided the ultimate security to the damaging structure.The results of research in this paper will have some referential value to the design and application of the unseating prevention devices.