Past Work on Hybrid Sliding Rocking Bridges

Intro

This concept of hybrid sliding-rocking (HSR) bridges was introduced by Dr. Sideris and his Ph.D. advisors, Dr. A. Aref and Dr. A. Filiatrault, for accelerated construction in high seismicity areas. HSR bridges included HSR columns and rocking superstructure girders. HSR columns are precast concrete segmental columns incorporating internal unbonded post-tensioning, sliding joints distributed over the column height, and rocking joints at the column ends. The rocking superstructure girders included internal unbonded post-tensioning and rocking-only joints. Minor joint sliding was possible for the superstructure girders, but it was not a primary response mechanism.

As part of this study, Dr. Sideris investigated HSR bridges through shake table testing on a large-scale bridge specimen and quasi-static testing on large-scale HSR columns.

Large-scale Shake Table Testing

Large scale testing was conducted on a large-scale (~1:2.39) single-span HSR bridge specimen to validate the concept of HSR members. The bridge specimen consisted of a single-cell box-girder rocking superstructure and two single-column HSR piers. The specimen was subjected to nearly 150 shake table tests executed in the Structural Engineering and Earthquake Simulation Laboratory (SEESL) of the University at Buffalo.

Tests considered:

Variations of specimen configurations with respect to the seismic mass and the superstructure-to-substructure connectivity.
Source-to-site distance effects (i.e., far-field and near-fault ground motion ensembles.
Several seismic hazard levels, including the design earthquake (DE), the maximum considered earthquake (MCE), and hazards exceeding the MCE.
Excitation directionality (i.e., bi-axial versus tri-axial base excitation)
Multiple-support excitation, associated with the wave propagation effects

Large-scale Quasi-Static Testing

The performance of HSR columns against high deformation demands (~ 15% drift ratio) was evaluated. The aspects of energy dissipation capacity, self-centering capabilities and induced damage were assessed. The influence of low and design-level post-tensioning was identified.

3D Finite Element Modeling

Models were generated using ABAQUS and focused on reproducing the response measured during large-scale quasi-static testing Contact interactions between adjacent segments and between the PT tendons and the segments were explicitly modeled.

Google Sites

Report abuse