nees facilities used: university of nevada, reno university of illinois, champaign-urbana...
TRANSCRIPT
NEES Facilities Used:
University of Nevada, Reno
University of Illinois, Champaign-Urbana
INTRODUCTION
Bridge columns are subjected to combinations of
actions and deformations, caused by spatially-complex
earthquake ground motions, features of structural
configurations and the interaction between input and
response characteristics. Combined actions/loadings
can have significant effects on the force and
deformation capacity of reinforced concrete columns,
resulting in unexpected large deformations and
extensive damage that in turn influences the
performance of bridges as vital components of
transportation systems. Current analysis methods,
behavior theories and design practices do not take into
consideration the full range of interactions, due to the
scarcity of experimental data and a lack of behavioral
understanding.
OBJECTIVES
Therefore, the objectives of the project are to develop
a fundamental knowledge of the impact of combined
actions on column performance and system response
and to establish analysis and design procedures that
include the impact. The objectives will be realized by
integrating analytical and experimental research where
physical tests are driven by analyses and simulations
that examine the system response of various bridge
types under different loading conditions, and analytical
models are calibrated by experimental data.
ANALYSIS AND DESIGN PROGRAM
The analysis and design program has the following
outcomes.
Comprehensive analyses of bridge configurations
resulting in guidelines on configurations and input
conditions that increase the likelihood of significant
complex-combined column loading.
Analysis tools for use by researchers and designers
to represent combination loading behaviors. These
will include new rigorous frame elements that account
for the complex three-dimensional behavior of
reinforced concrete (RC) columns under combined
loading and new constitutive models for combined
axial/bending/torsional actions to be used in
conjunction with the new inelastic frame elements.
Behavioral models, simplified analysis and design
tools to be used by engineers. Model and design
methodologies will be developed that address
(i) when engineers must include combination
load effects and
(ii) when they can be neglected.
Tools will include methods for estimating strength and
deformation capacity.
Drive files for the pseudo-dynamic and dynamic
experimental programs at University of Nevada, Reno
(UNR) and University of Illinois at Urbana-Champaign
(UIUC). The analytical work will serve as the driving
tool for conducting and linking the experimental
components of the project.
The outcomes will be realized through the following:
Task 1: Preliminary Analysis of Bridges under
Combined Loadings (UCLA, UIUC)
A preliminary analysis of a series of bridge structures
subject to different levels of earthquake excitations
using existing finite element software packages will be
performed at the first stage of the project.
Figure 1: UMR Experimental Setup
Figure 2: UIUC Experimental Setup
Figure 3: UNR Experimental Setup
Figure 4: V-M-T Interaction Diagram
EDUCATION AND OUTREACH
An integrated education, training and outreach
program has been developed for the project that spans
from 4th graders to practicing engineers. The
education component is being guided by University of
Washington, St. Louis. Modules will be developed for
teachers and professors that can be inserted in their
courses. Modules will be used by the research team
in summer camps, visits to local elementary, middle
and high schools, undergraduate and graduate
courses and in continuing education courses. Specific
programs are targeted towards underrepresented
groups. Summer camps are planned for the summer
2006 at both UNR and UMR.
Seismic Simulation and Design of Bridge Columns under Combined Seismic Simulation and Design of Bridge Columns under Combined Actions, and Implications on System ResponseActions, and Implications on System ResponseInvestigators:
David H. Sanders, University of Nevada, Reno (Principal Investigator)
Abdeldjelil “DJ” Belarbi, University of Missouri, Rolla (co-PI)
Pedro Silva , University of Missouri, Rolla (Investigator)
Ashraf Ayoub , University of Missouri, Rolla (Investigator)
Shirley Dyke, Washington University St. Louis (co-PI)
Amr Elnashai, University of Illinois, Champaign-Urbana (co-PI)
Jian Zhang, University of California, Los Angeles (co-PI)
Sergio Alcocer, University of Mexico, Mexico City (Investigator)
The bridges analyzed in the study will be selected to
represent conditions resulting in high levels of
combined loadings on the piers. The goal of the
analytical study is to study the seismic response of
these bridge systems, including foundations and
surrounding soils, so that the appropriate multi-
directional loading and boundary conditions for
columns can be obtained. The study is therefore
essential for determining the appropriate input
loadings for the specimens tested in the subsequent
phases of the project.
Task 2: Development of Inelastic Models for RC
Sections under Combined Loading (UMR)
This task will focus on developing new constitutive
models for RC under combined axial/bending/torsional
loads in conjunction with available inelastic frame-type
elements. The NEES-supported finite element open
source software OpenSees will be used as the
computational platform and the newly developed
constitutive models will be added to its material library.
The newly developed models will be used for pseudo-
dynamic testing, predicting dynamic columns
performance and for conducting fragility studies
Task 3: Modeling of Specimens under Pseudo-
Dynamic and Dynamic Conditions (UCLA, UMR,
UIUC, UNR)
The newly developed frame elements with calibrated
constitutive models for RC sections will be used to
model and provide input to the pseudo-dynamic
system simulation conducted at UIUC and the dynamic
tests at UNR.
Task 4: Correlation with System Bridge Test (Sanders)
A ¼-scale two-span bridge test was conducted at UNR
as part of NEES Collaborative Research: A
Demonstration of the NEES System for Studying Soil-
Foundation-Structure Interaction will enable both
elastic and inelastic calibration of specific models
developed.
Task 5: Fragility Analysis of Bridge Structures &
Impact of Dynamic Loads (UIUC, UMR, UNR)
The newly developed and calibrated frame elements
will be used to conduct extensive statistical studies
with the purpose of deriving probabilistic fragility
relationships for RC bridges including axial-shear-
flexure-torsion interaction.
EXPERIMENTAL PROGRAM
The experimental program includes quasi-static testing
of twenty-four large columns providing fundamental
behavior including the impact of torsional moments at
University of Missouri, Rolla (UMR) (see Fig. 1),
pseudo-dynamic testing of three large and four small
scale columns with variable axial load, within a bridge
system simulation, at the University of Illinois at
Urbana-Champaign (UIUC) (see Fig. 2), real-time
dynamic testing of eight large scale columns with
bidirectional, torsional and variable axial load inputs at
University of Nevada, Reno (UNR) (see Fig. 3), plus
an integrated experiment with three columns linked
through simulation, conducted at UIUC by UMR. The
tests will work to define the failure surface as seen in
Figure 4. The experimental program is fully integrated
with the analytical program.
Loading Frames
Load Stub
(2) Vertical Actuators
Unit Tie Downs
(2) Horizontal Actuators
Test Unit
Unit Base
Strong Floor/Wall
Test Unit
Tie Downs for (1) Horizontal Actuator
(1) Horizontal Actuator
Loading Frames
Load Stub
(2) Vertical Actuators
Unit Tie Downs
(2) Horizontal Actuators
Test Unit
Unit Base
Strong Floor/Wall
Test Unit
Tie Downs for (1) Horizontal Actuator
(1) Horizontal Actuator