Task NA 3.6 Preparatory Course on Seismic Qualification - Introduction To... · Preparatory Course on Seismic Qualification ... Jan 11-12 2011 What is Seismic Qualification? ... Final

Task NA 3.6Preparatory Course on Seismic QualificationBristol, 11-12 January 2011

Introduction to seismic qualification

Prof Colin Taylor, University of Bristol

SEISMIC ENGINEERING RESEARCH INFRASTRUCTURES FOR EUROPEAN SYNERGIES

SERIES Training Course - Bristol, Jan 11-12 2011

The presentation

Why seismic qualification?Origins and characteristics of earthquakesStructural response to earthquakesThe seismic qualification process▫ Test specifications▫ Required Response Spectra (RRS) and Test Response Spectra

(TRS)▫ Project documents▫ Test equipment and instrumentation▫ Exploratory tests▫ Seismic tests▫ Functional test



Sichuan, China, 12 May 2008

AP Photo/Kyodo News/Takanori Sekine

AP Photo/Kyodo News/Takanori Sekine

AP Photo color/China Photo

70,000+ dead

3 million homeless



Interior of Apartment Building

From http://www.smate.wwu.edu/teched/geology/eq-CA-Northridge1.html


SERIES Training Course - Bristol, Jan 11-12 2011From http://www.smate.wwu.edu/

Interior Damage to Schools


SERIES Training Course - Bristol, Jan 11-12 2011From http://www.theberkeleygraduate.com/2009/10/preparing-for-an-earthquake/From http://www.cfht.hawaii.edu/EARTHQUAKE/PHOTOS/IMGP0723_library1.JPG

Damage to Shelving and Storage



Sichuan – 12 May 2008

Source: USGS



Sichuan – 12/05/08 event & aftershocks

Source: USGS



Sichuan – thrust fault

Source: USGS

Source: USGS

Source: USGS



Northridge, California, Earthquake, 1994 24 Hour Seismogram



UK strong ground motion

Synthetic UK hard rock ground acceleration scaled to 1g PGA

-10

-5

0

5

10

15

0 1 2 3 4 5 6 7 8

Time / s

Acce

l / m

s-2



Seismic response



Elastic structural dynamic response

Mode 1 Mode 2 Mode 3



MDOF simulation and secondary structure response

4-storey with quake and tmd v8 090910.ds



Dynamic models

• Natural frequency and period

• Mass - m• Stiffness - k• Damping – c• Displacement - x

• Equation of motiongxmtPkxxcxm &&&&& −==++ )(

sradmk /=ω

ωπ2

=T seconds

Internal inertia force

Internal damping

force

Internal ‘stiffness’

force

External (earthquake)

force

Mass (m)

Relativedisplacement x(t)

Ground displacement

xg(t)

Damping( c )

Stiffness(k)



Elastic response

single elastic and single plastic with elastic tmd 240310.ds



Elastic response

0 10 20 30 40 50 60-10

-5

0

5

10El Centro, USA (May 1940), 270deg

time (s)

Tota

l Acc

el. (

m/s

/s)

0 10 20 30 40 50 60-10

-5

0

5

10

time (s)

Tota

l Acc

el. (

m/s

/s)

0 10 20 30 40 50 60-10

-5

0

5

10

time (s)

Tota

l Acc

el. (

m/s

/s)

T=0.2s

T=0.5s

T=1.0s

peak = 6.51m/s/s

peak = 8.34m/s/s

peak = 5.07m/s/s



0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 13

4

5

6

7

8

9

Period T (s)

Pea

k To

tal A

ccel

.(m/s

/s)

Acceleration Response Spectrum

Elastic acceleration response spectrum

6.51

8.34

5.07



Design response spectrum

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Period T (s)

Pea

k To

tal A

ccel

.(m/s

/s) A Design Spectrum



What is Seismic Qualification? One of many types of tests used to verify that a specimen can function under a range of

environmental conditions▫ Shake the specimen with representative earthquake loads▫ Numerical analysis▫ Reference to previous test database

Other environmental tests include:▫ Air temperature – High, Low, Change▫ Air – Pressure, speed▫ Humidity Range: Dry to Wet – especially for outdoors equipment▫ Water – Rain, ice & frost▫ Radiation – Solar , heat▫ Mechanical substances – Dust, sand▫ Chemical substances – Sulphur, chlorine, nitrogen, hydrogen fluoride, ozone▫ Flora and Fauna – Micro organisms, rodents, insects▫ Shock Loading – High g tests (up to 400g) normally by drop test▫ Office vibration – 1-100Hz sine sweeps 30 mins / sweep▫ EMC tests – Radio, microwave interference



Who needs Seismic Qualification?

Nuclear Industry▫ Power stations▫ Submarine bases

Telecoms Industry▫ Equipment (cabinets and contents)

for installation in Europe / USA / Japan / Taiwan etc.

Engineering Consultancies ▫ Validation of FE analysis

e.g. non-linear dynamic contact elements

Engineering Contractors▫ Testing of new materials / construction techniques



Test Specifications BELLCORE – NEBS

NEBSTM Requirements: Physical ProtectionTelcordia Technologies Generic RequirementsGR-63-CORE Issue 2, April 2002

IEC 60068-2-57 International Test StandardEnvironmental testing –Part 2-57: Tests – Test Ff: Vibration – Time-history method

ETSI EN 300 019-2-3 V2.2.2 (2003-04)European Standard (Telecommunications series)Environmental Engineering (EE); Environmental conditions and

environmental tests for telecommunications equipment; Part 2-3: Specification of environmental tests; Stationary use at weather protected locations

IEEE-87

Custom – British Energy



Telcordia Earthquake Zone Map

From GR-63-CORE Issue 2, April 2002


SERIES Training Course - Bristol, Jan 11-12 2011From GR-63-CORE Issue 2, April 2002

GR-63-CORE Response Spectra


SERIES Training Course - Bristol, Jan 11-12 2011From GR-63-CORE Issue 2, April 2002

GR-63-CORE Response Spectra



Develop specific secondary response spectra

Typically from dynamic FE analysis of building system

Calculate floor time history response and response spectra

Rules for idealising shape of spectra

▫ Peak broadening▫ Enveloping▫ etc



Typical Test SequencePreliminary meetings to agree test specification including:

Equipment requirementsMain test spectraNumber and amplitude of shakes Exploratory test requirementsDetails of functions testing

Preparation of test documentation – QP, TMSGenerate shakes ready for testingArrival of specimen, examination for transport damageMount specimen on shaking tableInstall instrumentationFunctional testsExploratory testsFunctional testsMain seismic tests including basic data processingFunctional testsRemove specimen from shaking table and return to clientFinal data processing and produce test report



Requirements of Test House

Necessary testing equipment – shaking tableAdditional equipment – power (3 phase), air line, water etc.Calibrated InstrumentsA fully operating QA systemSkilled operators

Within the University of Bristol BEELAB performs this role



Test Equipment – Shaking table



Project Documentation



Calibration Certificates



Typical Test Specimens• Electronics



Mounting Arrangements • Mounted as will be installed on site• Both location and style of connection



Instrumentation Acceleration:

Shaking table: 3 axisSpecimen Top: 3 axisSpecimen mid height : 3 axis

Displacement:Specimen Top: 2 axis



Exploratory Tests To ascertain main frequencies of test itemUse random excitation or sine sweeps. Excitation levels predefinedResults may be used to modify main test sequence

Results for a telecoms cabinet ( X and Y axes)

Main Natural Frequency: 9.8 Hz Damping: 2.4 %

Main Natural Frequency: 8.5 Hz Damping: 2.6 %



Exploratory Tests• Sine sweep test data• In-house processing of results



Functional TestsTo confirm test item operates after (and during) a seismic event



Typical Shake Sequences Triaxial Shakes:25%, 50%, 75%, 100%, 140% (and back down)5 at 25%, 1 at 100%, 1 at 140%5 at OBE, 1 DBE, 1 SSEOther combinations are possibleShakes more than 100% are used to check for “cliff edge” effects

Single Axis Shakes:BELLCORE100% each axis

-2.00

-1.50

-1.00

-0.50

0.00

0.50

1.00

1.50

2.00

0 5 10 15 20 25 30 35

Time (s)

Zone 4 accel (g)Zone 2 accel (g)



Signal shaping

Prescribed time history▫ E.g. Bellcore▫ Adjust table control to fit table motion to prescribed history within allowed

tolerances

Generate synthetic table time history that envelopes Required Response Spectrum▫ At key frequencies (e.g. 1/3rd octave) ▫ Iterative approach▫ Statistical independence of motions



Typical Test Specimens • Telecoms, Mechanical Equipment



Typical Test Specimens• Subsea unit for oil well Xmas tree - Operation and Transportation tests



Typical Test DataX axis - Run 1 Failed to envelope X axis - Run 2 Enveloped



Horizontal BELLCORE shakeExample Test



Documents

Task NA 3.6 Preparatory Course on Seismic Qualification - Introduction To... · Preparatory Course on Seismic Qualification ... Jan 11-12 2011 What is Seismic Qualification? ... Final