Almost all of the suspension bridges in the central and eastern U.S. (CEUS) were built long before seismic design concepts were understood and widely practiced. These bridges carry extremely high volumes of traffic, often in densely populated urban areas. Seismic demands on these bridges often exceed the capacities of the nonductile members. There is a need to retrofit these brides to ensure survival during and after seismic events.
The objective of this research is to evaluate the use of distributed supplemental damping in the retrofit of suspension bridges in the central and eastern portions of the United States. Supplemental damping is a type of passive control in which damping devices are incorporated into the structural system. Distributed damping refers to the placement of these devices evenly throughout the structure. Preliminary investigations of the system suggest that large reductions in response are possible.
The program of research shall consist of numerous activities intended to fulfill the above mentioned research objective:
O Collection and evaluation of strong motion records typical of sites in the CEUS. O Re-processing of collected records to recover long period content. O Extensive analytical modeling of typical suspension bridges. O Determination of most effective distribution of damping elements. O Evaluation of different damper types and characteristics. O Investigation into the reduction or elimination of stiffness from the stiffening truss system and its side effects. O Constructability and cost investigations of the proposed retrofit method.
Impacts of the research could include reduction of loss of life and economic losses following a major seismic event, improved design of isolation systems, longer and lighter future suspension bridges, and greater awareness of the seismic risks in the CEUS.
