Testing of interface components

Armelle ANTHOINE and Pierre PEGON

European Laboratory for Structural Assessment (ELSA)

Joint Research Centre (JRC)

Ispra, ITALY

SAFECONSTRUCT (European Standards) for Buildings and other Civil Engineering constructions under Earthquake, and other environmental and live loading

PVACS (European Guidelines) for Physical Vulnerability Assessment of Critical Structures under Impact and Blast loading

STEC (Performance standards for innovative technologies ) in the area of tamper-proof intermodal containers Supply Chain Security, Competitivness

ELSA Unit:

Actions and Activity fields

“Quasi-static” tests

Real size scale

Close loop

Dynamic tests

Reduced scale

Open loop

Earthquake simulation in the Lab

Shaking table

Reaction wall

3

The Pseudo-dynamic methods

4

Servo-Hydraulic

Actuators

Displacement

Transducers

Reference

Frame

Measured

Restoring Force )(tR

ga

dt...

Accelerogram

Force

Transducers

( ) ( ) ( ) gMa t Cv t R t MIa

Numerical Model

Imposed

Displacement ( )d t

Reaction wall at ELSA

22 actuators from 50t a 100t

2 testing platforms

Unique installation in Europe

Partner of infrastructure network

5

Bending moment

200 MNm

Bending moment

240 MNm

16m

4.2m

25m 4m 5m

20m

13m

20m

Anchor holes

1m spacing

Base Shear

20 MN

SERIES/SERFIN project (end 2011)

“Special tests”: TESSH project in IRIS

7

• Cyclic tests

• Cracking damage regime

• Ultimate state

• Control of the rotation

3m 1.2m

Thickness=40cm

Pipe crossing a seismic gap

8

Pipe characteristics

9

• DN300: Re = 157.5 mm, Ri = 142.5 mm, t = 25. mm

• p = 200. bar

• Gas (steam) or fluid (water)

• Temperature between 335oC and 500oC

• Geometry of the pipe: Z shape 6.25 m x 2 m

• Position and type of joints: 2 gimbals + 1 single hinge

• Boundary conditions: pipe clamped at both ends

Involved phenomena

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• Seismic loading Horizontal displacements imposed at one end

+ vertical displacement imposed at both ends

• Large displacement and rotations Geometric nonlinearity

• Internal pressure p Thrust in curved parts: T=2pR2cos(/2)

– Elbows

– Activated joints

• Fluid velocity vf Additional thrust: T=2fvf2R2cos(/2)

• Mass of the fluid f Higher weight and inertia (lower frequency)

Objective: Identify a representative test

Chosen numerical model

11

• Pipe:

Elastic Navier Bernoulli beam with hollow circular section. Steel

material (Es, s, s).

• Joint:

Elastic Navier Bernoulli beam with hollow circular section. Soft

material (Es/10000, s, s).

+

Timoshenko beam with hollow circular section but zero inertia in

the rotation axes (y and z or z only). Stiff material (100Es, s, s).

• Fluid/gas:

Internal pressure (+ possible mass flow) in the Navier Bernoulli

beams (p or p+fvf2).

+

Increased volumetric mass of the Navier Bernoulli beams.

Loading

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• Gravity :

Configuration independent load applied statically at the beginning

and maintained constant during the seismic loading.

• Pressure (and/or flow):

Configuration dependent load applied statically at the beginning

and actualised during the seismic loading.

• Seismic loading:

Imposed displacement history at the extremities of the pipe.

uz(t) at both extremities, ux(t) and uy(t) at one extremity only.

Seismic input

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Acceleration and displacement time histories

Response spectra for 2% damping

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Preliminary modal analysis

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• Configuration 1:

Displacements and rotations blocked at both ends

• Configuration 2:

ux and uy free at one end.

• With/without fluid mass

Results:

• Frequency

• modal mass

• participation factors in x, y and z

• mode shape

Modal analysis results without fluid

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Fre1 Fre2 Mas1 Mas2 PFx1 PFx2 PFy1 PFy2 PFz1 PFz2

- .406 - 666. - -.679 - .675 - 0

- 1.15 - 546. - .747 - .442 - 0

19.1 220. 0 0 1.48

46.3 - 471. - -.0323 - 1.26 - 0 -

- 51.1 - 392 - -.301 - -1.06 - 0

52.5 159 0 0 0.918

Modal analysis results with fluid

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Fre1 Fre2 Mas1 Mas2 PFx1 PFx2 PFy1 PFy2 PFz1 PFz2

- .327 - 1025. - -.679 - .675 - 0

- 0.927 - 842. - .747 - .442 - 0

15.4 337. 0 0 1.48

37.4 - 753 - -.0323 - 1.26 - 0 -

- 41,3 - 605 - -.301 - -1.06 - 0

42.8 240 0 0 0.912

Preliminary conclusions

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• Vertical seismic loading: the first mode with a participation in z

has a frequency > 15 Hz very low displacement amplitude

• Horizontal seismic loading: apart from the two mechanisms, the

first mode with a participation in x or y has a frequency > 37 Hz

very low displacement amplitude (?)

• Only the two mechanisms should be substantially activated.

BUT

• Effects of the geometric non-linearity and of the pressure thrust

have not been taken into account.

Loading

19

• Gravity :

Configuration independent load applied statically at the beginning

and maintained constant during the seismic loading.

• Pressure (and/or flow):

Configuration dependent load applied statically at the beginning

and actualised during the seismic loading.

• Seismic loading:

Imposed displacement history at the extremities of the pipe.

uz(t) at both extremities, ux(t) and uy(t) at one extremity only.

Non-linear calculations

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• Static/dynamic analysis (2% damping on the first mode > 15Hz)

Small differences on u and

• With/without vertical component Small differences on u and

• With/without internal pressure Small differences on u but large

differences on owing to the pressure.

• With/without fluid mass Small differences on u and , except

when the system reaches its limit.

Representative testing

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• The horizontal differential displacements can be imposed either

statically or dynamically.

• The vertical seismic displacements can be neglected

• The pipe should be pressurized (safety measures cost?)

• The fluid is not obligatory

Solution 1: 2-DoF shaking table on pressurized pipe

• Large stokes are required for full-scale specimens.

• Test velocity can be reduced

Solution 2: Bi-directional static loading on pressurized pipe

• Large strokes are available Full-scale specimens are allowed

• Test velocity can be increased

Possible setup

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ELSA setup: one actuator imposing ux at one end, another

actuator imposing uy at the other end.

Shake table setup: one end still, ux and uy imposed at the

other end.

Further analyses

23

High temperature (500oC) creep ?

More accurate behaviour of the joint (friction, angular spring

constant, return moment, etc.)

Possible movements of the isolated part: tests/calculations output

more realistic differential displacement histories