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Newmark Structural Laboratory Report Series (NSEL Report Series ISSN 1940-9826) >
Please use this identifier to cite this item:
http://hdl.handle.net/2142/3628
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| Title: |
Multi-dimensional Mixed-mode Hybrid Simulation Control and Applications |
| Authors: |
Nakata, Narutoshi
Spencer, Jr., Billie F.
Elnashai, Amr S. |
| Keywords: |
hybrid simulation
Mixed Load/Displacement Control
Reinforced Concrete Bridge
Seismic Performance of Structures |
| Issue Date: |
2007-Dec |
| Publisher: |
Newmark Structural Engineering Laboratory. University of Illinois at Urbana-Champaign. |
| Series Name / Report no.: |
Newmark Structural Engineering Laboratory Report Series 005 |
| Abstract / Summary: |
Hybrid simulation is an effective method for the assessment of the seismic response
of structures, combining laboratory testing, computational simulation, and numerical
time-step integration of the equations of motion. While this approach has been used for
evaluation of the seismic performance of a variety of structures, applications to date have
been limited to planar loading and to relatively simple structural systems. In contrast,
actions during strong earthquakes are three-dimensional and continuously varying and
modern structures can be extremely complex. Further development is required to evaluate
the seismic performance of structures, in particular complex structural systems, under
realistic loading.
The objectives of this study are to develop a multi-dimensional hybrid simulation
framework using a six-actuator, self-reaction, loading system, referred to as the Load and
Boundary Condition Box (LBCB), for evaluation of the seismic performance of large and
complex structural systems and to demonstrate the framework through three-dimensional
hybrid simulation of a skew reinforced concrete (RC) bridge. This report contains results
for four major tasks that are intended to provide enhanced seismic performance
evaluation using advance experimental techniques.
The first task is the calibration of the LBCB in global Cartesian coordinates. Due to
imperfections in system geometry (e.g., the actuator configuration), errors in the
Cartesian measurements are generated from errors in the transformation from actuator to
Cartesian space. A sensitivity-based external calibration method is developed to improve
the precision by which the LBCB can be controlled in Cartesian space.
The second task is to develop, implement, and experimentally verify a mixed load
and displacement (mixed-mode) control strategy. A mixed-mode control capability is
required, for example, to simulate gravity loads in the axial direction and displacements
in the other directions on structural members such as RC piers in hybrid simulation.
However, because of the nonlinear nature of the coordinate transformation, mixed-mode
control for a multi-axial loading system is still a major theoretical and practical challenge.
The mixed-mode control strategy developed in this study accounts for the spatial
interaction of actuators both in displacement and load, and the stiffness variation of the
structure specimen.
The third task is to integrate the control system and its capabilities into a hybrid
simulation framework. The framework needs to also incorporate robust network
communication for hybrid simulation.
The fourth and final task is to validate the hybrid simulation framework through the
study of the three-dimensional behavior of a skew RC bridge. First, extensive analyses of
skew bridges are conducted to prepare for the hybrid simulation. Subsequently, a smallscale
RC pier is experimentally tested as a physical substructure, while the rest of the
piers and the bridge deck are analyzed using a finite element model. The mixed-mode
control capability is employed to impose on the RC pier simultaneous gravity loads in the
axial direction and earthquake-induced displacements in the other directions. The
experimental results show that the multi-dimensional hybrid simulation with versatile six
degrees-of-freedom loading capability is a promising approach that provides a reliable
means for evaluation of the seismic performance of large and complex structural systems. |
| URI: |
http://hdl.handle.net/2142/3628 |
| ISSN: |
1940-9826 |
| Type of Resource: |
text |
| Genre of Resource: |
technical report |
| Publication Status: |
published or submitted for publication |
| Appears in Collections: |
Newmark Structural Laboratory Report Series (NSEL Report Series ISSN 1940-9826)
|
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NSEL Report.005.pdf (16Mb)
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report 05 |
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