Dynamics and Seismic Performance of Bridges with Rocking Piers of Nonconventional Configuration

Abstract

The present study focuses on the seismic response of bridges with rocking piers of nonconventional shape, combining the inherent benefits of rocking isolation and accelerated bridge construction. The governing equations of motion of bridge structures with different configurations of piers are derived, including the basic kinematics of the rocking motion, the equation of motion during rocking, as well as the intrinsic energy dissipation mechanisms of impact at the rocking interfaces and on the abutment backwalls. This analytical framework is based on dimensionless parameters that are related to the shape of the piers, and it is shown that the reduction of mass that is achieved with the nonconventional pier configurations leads to: (1) lower restoring effects compared to conventional piers that are rectangular in elevation; and (2) higher rocking stability based on rocking principles. The efficiency of the proposed pier configurations in a bridge with rocking pier isolation is examined for different levels of seismic action, also including earthquakes much stronger than the design earthquake in the area. It is demonstrated that the proposed nonconventional pier configurations can improve the seismic performance of rocking bridges, and at the same time bring benefits related to economic and sustainability aspects associated with a reduction in the use of construction materials.