1. CABER Project Update February 22, 2008
Feb 2 and 3, 2004
Seismic Simulation and Design of Bridge Columns
under Combined Actions, and Implications on System Response
CABER Project Update February 22, 2008
Amr S. Elnashai
Sung Jig Kim
Curtis Holub
NEES MUST-SIM Site Visit

2. Outline Simulation Overview Data Acquisition
Feb 2 and 3, 2004
Simulation Overview
Data Acquisition
Control (Elastic Deformations)
Test Results and Comparisons
Future Tests
NEES MUST-SIM Site Visit

3. Simulation Overview Configuration
Feb 2 and 3, 2004
Configuration
Prototype: FHWA design example 4 (1996)
Single ½ scale experimental pier
Zeus-NL model of remaining 3 piers and bridge deck
NEES MUST-SIM Site Visit

4. Analytical Model FE software: Zeus-NL with shear spring
Feb 2 and 3, 2004
FE software: Zeus-NL with shear spring
Parameters for shear spring are calculated from R2K
Ang et al (1985), S-17
Shear Spring
Force or Displ.
Beam Element
NEES MUST-SIM Site Visit

5. Experimental Model Material and Section Properties Concrete: 5900 psi
Feb 2 and 3, 2004
Material and Section Properties
Concrete: 5900 psi
Longitudinal bar: 16-#8 (2.8%), Fy = 62 ksi
Spiral: #3, Fy = 75 ksi
Plastic hinge zone: s = 2.5 in (0.85%)
Center region: s= 4.25 in (0.50%)
NEES MUST-SIM Site Visit

6. Data Acquisition Traditional Data Acquisition (91 total channels)
Feb 2 and 3, 2004
Traditional Data Acquisition (91 total channels)
51 strain gages
24 curvature measurements (linear pots)
10 translation measurements (string pots)
6 slip/uplift measurements (LVDTs)
Krypton Measurements (25 LEDS)
5 high resolution still cameras (Stepwise and handheld)
Video
1 high resolution video camera
1 telepresence camera
Control
6 actuator displacements and 6 forces
6 Cartesian displacements and 6 forces
5 external feedback sensors
NEES MUST-SIM Site Visit

7. Elastic Deformations Problem Definition Solution
Feb 2 and 3, 2004
Problem Definition
Displacement controlled test
0.001 inch = 20 kip
LBCB platen movement controlled internally
LBCB frame, pier caps, reaction wall/floor have finite stiffness
Internal actuator displacements are contain both specimen and external deformations
Solution
A external measurement and feedback system was developed
NEES MUST-SIM Site Visit

8. Measurement and Feedback
Feb 2 and 3, 2004
4 DOF (x,z,ry,rx) measurement system
System of 5 high tension string pots with low friction connections
Exactly monitors movement between the two end caps
Geometric nonlinearities are completed handled in transformation
System is completely reconfigurable and can handle any combinations of DOFs
Feedback
Internal actuator commands are adjusted to achieve desired displ. target
String pot
Extension wire
NEES MUST-SIM Site Visit

9. Ground Motion Northridge Earthquake (Mw 6.7) V/H ratio: 1.2
Feb 2 and 3, 2004
Northridge Earthquake (Mw 6.7)
Sylmar Converter Station
PGA: HGM – 0.583g, VGM – 0.548g
V/H ratio: 1.2
PGA of VGM was
scaled up to 0.734g
NEES MUST-SIM Site Visit

10. Feb 2 and 3, 2004
Test Result
PIER 1: HGM
NEES MUST-SIM Site Visit

11. Test Result PIER 2: HGM + VGM Feb 2 and 3, 2004
NEES MUST-SIM Site Visit

12. Comparison between Pier 1 and 2
Feb 2 and 3, 2004
NEES MUST-SIM Site Visit

13. Strains of Longitudinal bar
Feb 2 and 3, 2004
NEES MUST-SIM Site Visit

14. Strains of Spiral
Feb 2 and 3, 2004
NEES MUST-SIM Site Visit

15. Feb 2 and 3, 2004
Comparison
PIER 1
PIER 2
NEES MUST-SIM Site Visit

16. Piers 3 and 4

17. Specimen Modification
18 inch bottom cap extension
Aspect ratio
Piers 1 & 2 = 2.5
Piers 3 & 4 = 2.1

18. Plans for Piers 3 and 4 Pushover test with different axial load levels
Feb 2 and 3, 2004
Pushover test with different axial load levels
PIER 3: Axial load = 50 k, Shear Failure
PIER 4: Axial load = -300k, Flexural Dominant Failure
NEES MUST-SIM Site Visit

19. Questions?