Typical earthquake damage and seismic isolation technology for bridges subjected to near-fault ground motions

Near-fault ground motions generally contain long-period velocity pulses and release huge energy. Severe earthquake damage has been observed in bridges subjected to near-fault ground motions. Moreover, some commonly-used seismic isolation devices cannot balance the relationship between forces and displacements in the structural system. This paper analyzes the typical earthquake damage for bridges subjected to near-fault ground motions by collecting the seismic investigation reports and concludes that deck shifting and unseating are the most typical seismic damage for bridges in the near-fault regions. Constitutive relationship design is the pivotal issue for the seismic isolator design of bridges. Combined with the design method for constitutive relationship of seismic isolation devices, a series of seismic isolation devices for bridges in the near-fault regions are proposed including Buffer cable-sliding friction aseismic bearings (BCSFABs), Steel mesh-reinforced isolation rubber bearings (SMIRBs) and cable-sliding modular expansion joints (CMEJs). Their working principles are introduced, respectively. Easy-repairability, wide-applicability and designability are one of the main developing trends for seismic isolation devices of bridges.