Connections for Integral Jointless Bridges in Seismic Regions Suitable for Accelerated Bridge Construction

Abstract

Prefabricated jointless bridges consisting of pretensioned girders, posttensioned spliced girders, trapezoidal open box girders, and other types of superstructure members are often used for accelerated bridge construction. Connections in precast concrete substructures are typically made at the beam–column and column–foundation interfaces to facilitate fabrication and transportation. However, for structures in seismic regions, those interfaces represent locations of high moments and shears and large inelastic cyclic strain reversals. Jointless bridge superstructures are constructed to work integrally with the abutments. Movements due to creep, shrinkage, and temperature changes are accommodated by using flexible bearings or foundation and through incorporating relief joints at the ends of the approach slabs. In addition to reduced maintenance costs, other advantages of jointless bridges include improved structural integrity, reliability and redundancy, improved long-term serviceability, improved riding surface, reduced initial cost, and improved aesthetics. In recent times, jointless bridges have been built in seismically sensitive areas. Developing connections that can accommodate inelastic cyclic deformations and are readily constructible is the primary challenge for accelerated bridge construction in seismic regions. The AASHTO load and resistance factor design specifications do not explicitly address jointless precast, pretensioned, or posttensioned elements. The seismic design and detailing, accomplished research, and construction practices of jointless bridges, and implementation of a precast concrete bridge bent system that is intended to meet all those challenges, are presented. This paper attempts to capture the state of practice of jointless continuous bridges in seismic regions.