Design, Modeling, and Experimental Response of Seismic Resistant Bridge Piers with Posttensioned Dissipating Connections

An increasing interest in the development of high-performance seismic resisting systems based on posttensioned, jointed ductile connections has been observed in the last decade. The extensive experimental and numerical studies carried out under the PRESSS program developed efficient alternative solutions for seismic resisting frame or wall systems in precast concrete building construction, typically referred to as jointed ductile connections. Low structural damage and self-centering behavior, leading to negligible residual displacements after an earthquake event, were recognized to be the main features of such systems. Recently, the extension and application of similar technology and seismic design methodologies to bridge piers and systems have been proposed in the literature as a viable and promising alternative to traditional cast-in situ or precast construction. However, a broad acceptance of these solutions in the bridge design and construction industry has yet to be observed. Valid justifications can be found in the lack of official guidelines for design and construction detailing as well as in the general apparent complexity of the design procedure and analytical models presented by the scientific community. In this contribution, confirmations of the unique design flexibility, the ease of construction, and the high seismic performance of jointed ductile hybrid systems, combining recentering and dissipation capabilities, are presented. After a presentation of simple design methodologies and modeling aspects herein adopted to fully control the seismic response of these systems, the experimental results of quasistatic cyclic tests on five 1:3 scaled, bridge pier specimens are reported and discussed. Four alternative hybrid configurations are implemented by varying the ratio between the posttensioning steel and the internal mild steel as well as the initial posttensioning load. Lower levels of damage and negligible residual/permanent deformations are observed in the hybrid solutions when compared to the experimental response of the benchmark specimen, representing a typical monolithic (cast-in situ) ductile solution. In addition, the efficiency of the simple analytical procedure adopted for design and modeling is further validated.