Seismic Performance of Multisimple-Span Bridges Retrofitted with Link Slabs

During earthquakes multisimple-span bridges are vulnerable to span separation at their expansion joints. A common way of preventing unseating of spans is to have cable or rod restrainers that provide connections between adjacent spans. Alternatively, dislocation of the girders can be controlled with a link slab that is the continuous portion of the bridge deck between simple spans. Seismic retrofit with link slab should be more cost-effective than the existing methods when it is performed during redecking or removal of expansion joints. Maintenance cost associated with expansion joints could also be reduced. This paper discusses the use of link slabs for retrofit of seismically deficient multisimple-span bridges with precast, prestressed concrete girders. The concept is equally applicable to bridges with steel girders. Analytical studies for typical overpasses were performed to investigate the effectiveness of the proposed link slab application. A simple preliminary design procedure was also developed.