Seismic Performance of Reinf. Conc. Bridges Allowed to Uplift during Multi-Direction

[asim99]

Seismic Performance of Reinforced Concrete Bridges Allowed to Uplift during Multi-Directional Excitation

Author: Andres Oscar Espinoza, Stephen A. Mahin | Size: 24 MB | Format: PDF | Quality: Unspecified | Publisher: PEER | Year: 2012 | pages: 338

The behavior of bridges subjected to recent moderate and large earthquakes has led to bridge
design detailed for better seismic performance, particularly through wider bridge foundations to
handle larger expected design forces. Foundation uplift, which is not employed in conventional
bridge design, has been identified as an important mechanism, in conjunction with structural
yielding and soil-structure interaction that may dissipate energy during earthquakes. Preventing
uplift through wider foundations looks past the technical and economic feasibility of allowing
foundation uplift during seismic events. The research presented in this study is part of a larger
experimental and analytical investigation to develop and validate design methods for bridge piers
on shallow foundations allowed to uplift during seismic events.
Several analytical and some experimental studies have been performed to assess rocking
and or uplift of shallow foundation systems, however they have evaluated systems with a limited
range of footing dimensions and seismic excitations. As such, there is an uncertainty in the
information needed to base a performance evaluation and develop design methods. The purpose
of this study is to investigate through experimental and analytical studies the seismic
performance of uplifting bridge piers on shallow foundations when considering different ground
motions and footing dimensions, as well as identifying key differences in performance
evaluation criteria for conventional and uplifting bridge pier systems.
The experimental study dynamically tested a single reinforced concrete bridge column
specimen with three adjustable footing configurations grouped by footing dimension, and tested
for various combinations of one, two, and three components of seismic excitation. Groups one
and two evaluated uplifting systems where the column was limited to elastic loading levels while
group three considered inelastic column loading levels. All test groups remained stable and
exhibited some rocking and or uplift during testing. Analytical models were developed and
validated using the experimental testing results to predict local and global footing and column
response. Reliable estimates of forces and displacements during elastic and inelastic response
were achieved. To assess the seismic performance of a range of bridge pier systems allowed to
uplift a parametric investigation using the validated analytical models was performed in which
the column was modeled per conventional design criteria to ensure adequate strength and
flexural ductility. The parameters varied include footing width, ground motion excitation, and
elastic or inelastic column response. Response of the uplifting bridge pier systems was found to
be sensitive to the structural periods, magnitude of excitation, and footing width.

Code:

***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:

http://forum.civilea.com/thread-27464.html
***************************************

This post has been made by CivilEA Post-Generator ver 2.1.6