DESIGNING SMART BRIDGES TO CONTROL EARTHQUAKE DAMAGE

The reduction of seismic forces and their favorable distribution among the bridge piers are possible by using dynamic isolation supports. Such supports resist transient working loads and force the occurrence of scismic forces of much smaller magnitude as compared with conventionally supported bridges.The force-deformation relationship of a dynamic isolation suppon is bi-linear. The initial stiffness provides resistance for wind, braking and centrifugal forces. The bi-linear part which goes into action during the earthquake elongates the natural period of the bridge as a result of which much smaller seismic forces are generated. Additionally, the small seismic force can be equally distributed among the bridge piers. The engineer is no longer forced to design a heavy pier because the seismic force is concentrated on this stiff pier. Necessary design equations and criteria are developed. A practical bridge example is presented that is equipped with dynamic isolation supports