Experience with OpenFresco: Reinforced Concrete Bridge

Department of Civil and Environmental Engineering

University of California, Berkeley

Experience with OpenFresco: Reinforced Concrete Bridge

Vesna Terzic

[email protected]

Objective Can a damaged bridge carry a heavy truck after

an earthquake?

It is very difficult to physically model the

bridge with the (moving) truck on it

hybrid simulation is

the way to go

2

Components of a Hybrid Simulation

3

Schellenberg, 2008

Five span, single column bent overpass bridge

Prototype Bridge

4

Ketchum et. al., 2004

Hybrid Model of the Bridge

5

Analytical model (full scale)

Physical model (SF=4.6875)

Geometry of the Specimen

6

Diameter

Longitudinal reinforcement

Transverse reinforcement

Concrete

16’’ (40 cm)

12#4 Gr60 ( l=1.2%)

[email protected] in ( t=0.75%)

fc=5 ksi (34.5 MPa)

Calibration of the Analytical Model Bridge columns – nonlinear elements

Damage is concentrated at plastic hinges

To calibrate analytical model (used in HS)

bi-lateral quasi-static test was performed

Identical specimens

7

Quasi-Static Test

8

Experimental Setup

Load Pattern

Material Calibration

Lateral Hystereses

X direction Y direction

Analytical Portion of the Hybrid Model

Modeled in OpenSees (3D model)

Deck: linear elastic elements

Columns: force based nonlinear beam-

column elements (calibrated based on quasi-static test)

Abutments: rollers in both directions

Integration scheme: Alpha-OS ( =0.9)

9

Physical Portion of the Hybrid Model

Scaled model (SF=4.6875)

OpenFresco was used for hybrid simulation

10

Experimental beam-

column element

Loads Applied on the Bridge Gravity load

Earthquake load in X and Y direction

11

Truck load

What are we going to control?

12

There are 6 DOFs that could be controlled at the

top node of the column:

ux , uy , uz , x , y , z

We are controlling 4 DOFs:

ux , uy , x , y

Assuming that rotation ( z ) and displacement (uz ) are small enough that they can be neglected.

ExpSetup: Lateral Displacements To control the 4 chosen DOFs we will use 4 actuators:

13

Rigid Body

ExpSetup: Axial Load

14

Geometric Transformations: Displacements

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d1 d2

d3 d4

x

y

Nonlinear Transformation in

ESFourActuators3d

ux

uy

x y

X direction Y direction

Geometric Transformations: Forces

16

Px Py Note: Axial force will

also create moments at CP

Deformed configuration

Initial configuration

f1 f2

f3 f4

Nonlinear Transformation in

ESFourActuators3d

qx

qy

mx my

f6 f5

x

y

OpenFresco Interaction with OpenSees

In FE model (OpenSees framework):

loadPackage OpenFresco

Define experimental control

Define experimental setup

Define experimental site

Define experimental element

17

OpenFresco Interaction with OpenSees

In FE model (OpenSees framework):

loadPackage OpenFresco

Define experimental control

Define experimental setup

Define experimental site

Define experimental element

18

OpenFresco Experimental Setup ESElementName.h

ESElementName.cpp

TclExpSetupCommand.cpp

19

OpenFresco: ESFourActuators3D.h

20

21

OpenFresco: ESFourActuators3D.h

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OpenFresco: ESFourActuators3D.cpp

OpenFresco: ESFourActuators3D.cpp

23

OpenFresco: ESFourActuators3D.cpp

24

25

OpenFresco: ESFourActuators3D.cpp

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OpenFresco: ESFourActuators3D.cpp

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OpenFresco: ESFourActuators3D.cpp

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OpenFresco: ESFourActuators3D.cpp

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OpenFresco: ESFourActuators3D.cpp

Definition of ExpSetup in TCL Script

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Units in analytical model: kN, m Units in experimental setup: kips, in

Scaling factors: Sd=4.6875 Sf=1/Sd

2

Sm=1/Sd3

Results: Displacements

31

Results: Forces

32

Four truck positions on a bridge

Department of Civil and Environmental Engineering

University of California, Berkeley

Questions? Thank you!

http://openfresco.neesforge.nees.org

The development of OpenFresco has been sponsored in parts by the

National Science Foundation through grants from the NEES Consortium, Inc.