compared effects of earthquakes, tsunamis & aircraft crashes on … · 2016. 1. 22. · french...

Compared effects of earthquakes, tsunamis & aircraft crashes on base- isolated massive structures

P. Labbé

International Innovation Workshopon Tsunami, Snow Avalanche & Flash Flood Energy Dissipation

January 21-22, 2016Maison Villemanzy, Lyon, France

Tsunami Workshop, Lyon, Jan 2016 2

� Introduction: French experience in seismically isolated nuclear structures

� Respective features of earthquake, tsunami & aircraft crash in terms of structural dynamics

� Response of a typical seismicallyisolated massive structure to such inputs


French exp. in seismically isolated nuclear structu res

Cruas NPPCruas NPP



A common raft for 2 units 401 pedestals, 1812 padsimplemented by Freyssinet (now Nuvia)

Operation: 1984, 1985PGA: 0.3 gFrequency: 1 HzPad size: 500x500x60 mmG modulus: 1.1 MPa



First application of antiseismic friction bearingsImplemented by FreyssinetEDF Spie-Batignolles patent

2 x 900 MW units, 1976-1985,built by French companies:- Spie Batignolles (civil work)- Framatome (now Areva)- Alsthom

Operation: 1984, 1985PGA: 0.3 gFrequency: 0.75 HzPad size: 700x700x130 mmG modulus: 1.4 MPa

KoebergKoeberg NPPNPP



Operation: 1985PGA: 0.2 gFrequency: 0.85 HzPad size: 700x700x147 mmG modulus: 1.1 MPa

La Hague La Hague spentspent fuel poolsfuel pools



Georges Besse II Georges Besse II enrichmentenrichment facilityfacility

Pavia Testing facility

Operation: 2010PGA: 0.3 gPad size: Ø500x400 mmG modulus: 0.7 MPa



Jules Horowitz Jules Horowitz ResearchResearch ReactorReactor

Under constructionPGA: 0.32 gFrequency: 0.60 HzPad size: 900x900x181 mmG modulus: 1.1 MPa

100 MW100 MW



Under constructionPGA: 0.32 gFrequency: 0.55 HzPad size: 900x900x181 mmG modulus: 1.1 MPa

ITERITERITERITERITERITERITERITERInternational Thermonuclear Experimental ReactorInternational Thermonuclear Experimental ReactorInternational Thermonuclear Experimental ReactorInternational Thermonuclear Experimental Reactor

2012



A synthesis of the French practice and experience on seismic isolation of nuclear facilities is available by AFCEN (*) :

French Experience and Practice of Seismically Isolated Nuclear Facilities

(*) FRENCH ASSOCIATION FOR DESIGN, CONSTRUCTION AND IN-SERVICE INSPECTION RULES FOR NUCLEAR ISLAND COMP ONENTS


Features of base-isolated nuclear facilities

A rigid body mode at a natural period of 1s or more


�Introduction

�Respective features of earthquake, tsunami & aircraft crash in terms of structural dynamics

�Response of a typical seismically isolated massive structure to such inputs


Features of inputs

� Seismic input

Onagawa NPP


� Seismic input

Same spectral amplification

Same PGA: 0.67g

Low frequency content

High frequency content

Input motions considered in this presentation

Features of inputs


Features of inputs

The sign of the seismic input motion (accelerogram) changes in a 0.1s typical time lag, which is short compared to stuctural eigenperiods.

0.1 s

� Seismic input

Onagawa NPP

Features of inputs

The seismic input is an imposed motion at the base of the structure.

For practical reasons it is also regarded by engineers as an ‘inertia force’. However the concept of inertia force is misleading. 1g

ΓΓΓΓ=0.67g

� Seismic input

Onagawa NPP


Fukushima NPP March 11 th 2011 h

� Tsunami input

V0 = Fr (gh)1/2

Fr : Froude number

According to Robertson et al. (2011) :1.5 < Fr < 2.5

Typically Fr =2 leads to : V0=20 m/s for h=10m,

which values are selected in this presentation

Features of inputs


� Tsunami input

The tsunami load is an imposedforce on the structure, appliedon a rather long period of time.

V0 h

∆∆∆∆h

F(t)

pressure

F(t)

s1 5

FB

FB is calculated by the momentum (impulse) equation :(Cross 1967)

FB = FS (1+ 2Fr ²) , with FS = ½ ρ g h² b

Features of inputs


� Aircraft Crash m V0

F(t) is calculated by the momentum (impulse) equation(Riera 1968)

Mass density Static buckling for ce

Features of inputs


� Aircraft Crash

∫ F dt = mV 0

The crash load is acting for a short period of time.A significant part of the kinetic energy is dissipated.

0.1 s

m=500 t and V0 = 150 m/s are chosen in this presentation.

Features of inputs


� Introduction

� Respective features of earthquake, tsunami & aircraft crash in terms of structural dynamics

� Response of a typical seismicallyisolated massive structure to such inputs


10 m

30 m100 m- 200 000 t- 8 MPa on bearings pads- f0=0.5 Hz , T0 = 2s- G = 1.4 MPa

�� 16 cm thick pads

Response of an isolated NPP structure

Typical seismically isolated NPP structure

16 x 1.2 = 19 cm

5% natural damping


3,5 cm

50 cm

An additional damping system is necessary for a 40% total damping.

A (natural) 5% damping of the isolation system is sufficient.


� Seismic input


�Tsunami input

20m/s h=10m

∆∆∆∆h=20 m

11 cm static

F(t)

s1 5 An additional damping system is also necessary

225 MN

x(t)

s1 5

11 cm

Max = 19 cm under 17%damping


FB



�Aircraft crash, symetrical impact

500 t 150 m/s

11 cm (5% damping)

200 000 t v0 = 0.37 m/s Momentum equation

T crash =0.1s << T0=2s



�Aircraft crash, torsion effects

100 m

50 m

10 m

35 c

m


Conclusion

Base isolation of massive structures is generally designed at long natural period (1s or more).

The respective effects of earthquake, tsunami and aircraft crash on the isolation system can be easily estimated. They are basically comparable. Regarding aircraft crash, the load excentricity should not be neglected.

A consequence of the long natural period is that, for base-isolated structures,

- the seismic input motion acts as a displacement-controlled load,

- the tsunami wave as a force-controlled load,- the aircraft crash as a momentum-controlled load.

Thank you for your kind attention

compared effects of earthquakes, tsunamis & aircraft crashes on … · 2016. 1. 22. · french...

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