Extreme Bridge Loads
Full Session with Abstracts
340050-1 - Computational and Experimental Seismic Performance Evaluation of Hybrid Sliding-Rocking Bridges
Friday, April 20
1:30 PM - 5:00 PM
This presentation discusses the seismic performance of Hybrid Sliding-Rocking (HSR) bridges considering design variations with respect to major design parameters and under different loading conditions. To achieve these objectives, computational simulations on two-span bridges and experimental studies on large-scale columns are performed.
The HSR bridges consist of precast concrete segmental substructures and superstructures. The substructure (HSR) columns incorporate internal unbonded post-tensioning, end rocking joints and sliding joints at selected locations. The unbonded post-tensioning and rocking joints together with the sliding joints provide the HSR columns with self-centering and energy dissipation capabilities, making the HSR bridges a suitable choice in the context of Accelerated Bridge Construction (ABC) for highly seismic regions. The early proof-of-concept large-scale quasi-static and shake table tests conducted at the University at Buffalo on HSR columns and an HSR bridge demonstrated the effectiveness of the proposed concept in mitigating damage under severe seismic loads. However, these studies did not investigate the effects of major design parameters on the seismic performance of HSR bridges. Such investigations were further hindered by the lack of robust and computationally efficient simulation models capable of capturing the dynamic response of HSR columns. In order to tackle the above-mentioned challenges, the authors recently developed an innovative two-node force-based beam-column element formulation, which can capture rocking-sliding interactions between adjacent column segments and has been successfully adopted to reproduce the existing experimental data.
In this study, three-dimensional models of two-span HSR bridges created utilizing the proposed element formulation are used to examine the effects of various design parameters on the seismic performance of HSR bridges. The design parameters examined are: (i) number and location of sliding joints, (ii) sliding amplitude, (iii) joint friction properties, (iv) tendons post-tensioning force ratio, and (v) cross-section shape. In addition, both single- and three-column substructure bents are considered to examine the effects of column boundary conditions. The effect of vertical excitation is also explored. Based on these examinations, recommendations are made on optimal design of HSR columns.
These optimal design recommendations are subsequently assessed through testing of large-scale HSR columns subjected to lateral cyclic loading and dynamic loading based on the findings of the computational studies. Of particular interest is the design and response validation of the sliding joints, which will include various interface materials, such as Teflon-steel, Teflon-Teflon, etc. These tests will also assess column damage and residual strength at various displacement demands, and validate predictions from simulation models.
• Given the large number of structurally deficient and functionally obsolete bridges in the US and around the world, the topic of this presentation is of regional, national and international interest.
• This presentation is useful to structural, bridge, and earthquake engineers as wells as bridge design code developers and construction engineers from academia and practice.
• The audience will be introduced to novel bridge technologies in the framework of Seismic ABC, novel computational simulation capabilities for HSR bridges, performance advantages of HSR bridges and large-scale experimental validations. The presented concepts can be used to expand other research areas and in teaching curricula.