innovative anti -seismic systems: lnec experimental … · 2009. 2. 4. · anti-seismic systems...

Maria João Falcão SilvaMaria João Falcão SilvaPhDPhD grantgrant holderholder FCT/LNECFCT/LNEC

INNOVATIVE ANTIINNOVATIVE ANTI --SEISMIC SYSTEMS: SEISMIC SYSTEMS: LNEC experimental research and futureLNEC experimental research and future

developmentsdevelopments

11 INTRODUCTIONINTRODUCTION

22 ANTIANTI--SEISMIC SYSTEMS: General SEISMIC SYSTEMS: General AspectsAspects

33 LNEC EXPERIENCE IN ANTILNEC EXPERIENCE IN ANTI--SEISMIC SEISMIC

SYSTEMSSYSTEMS

44 LNEC FUTURE DEVELOPMENTS IN ANTILNEC FUTURE DEVELOPMENTS IN ANTI--

SEISMIC SYSTEMSSEISMIC SYSTEMS

55 CONCLUSIONSCONCLUSIONS

CONTENTS

INNOVATIVE ANTI-SEISMIC SYSTEMS: LNEC experimental research and future developments

11 INTRODUCTIONINTRODUCTION

222 ANTIANTIANTI---SEISMIC SYSTEMS: General SEISMIC SYSTEMS: General SEISMIC SYSTEMS: General AspectsAspectsAspects

333 LNEC EXPERIENCE IN ANTILNEC EXPERIENCE IN ANTILNEC EXPERIENCE IN ANTI---SEISMIC SEISMIC SEISMIC

SYSTEMSSYSTEMSSYSTEMS

444 LNEC FUTURE DEVELOPMENTS IN ANTILNEC FUTURE DEVELOPMENTS IN ANTILNEC FUTURE DEVELOPMENTS IN ANTI---

SEISMIC SYSTEMSSEISMIC SYSTEMSSEISMIC SYSTEMS

555 CONCLUSIONSCONCLUSIONSCONCLUSIONS

CONTENTS


> Increasing in the research of innovative anti-seismicsystems

> Increasing concern with the achievement of solutions thatminimize the effect of the dynamic actions (wind andearthquakes)

> Increasing concern of the responsibles (constructioncompanies, civil protection, government and final users) for questions related with the reduction/mitigation of dinamicactions

> Search for a good relation cost-benefit and easy applicationdevices

INTRODUCTION


111 INTRODUCTIONINTRODUCTIONINTRODUCTION

22 ANTIANTI--SEISMIC SYSTEMS: General SEISMIC SYSTEMS: General AspectsAspects






CONTENTS


ANTI-SEISMIC SYSTEMS


Anti-seismic systems

Passive Active Hybrid Semi-Active

Seismic Isolation Energy Dissipators

Metallic Dampers

Friction Dampers

Viscoelastic Dampers

Viscous Fluid Dampers

Tuned Mass Dampers

Tuned Liquid Dampers

Smart Materials





Seismic Isolation

Based on the possibility of supressing theconnections in the horizontal plan, between the structure and the foundationsoil (horizontal movement of the structureindependent of the soil’s horizontal movement)





Energy Dissipators

Specially designed for dissipating energy, while thestructures in which are included present deformation

Excitation Structure Response

ED





Energy Dissipators

Metallic Dampers

Friction Dampers

Viscoelastic Dampers

Viscous Fluid Dampers

Tuned Mass Dampers

Tuned Liquid Dampers

Shape Memory Alloys





These devices, based on the data obtained through the constant monitoringof the structure, are able to react against the movements imposed by theseismic action


Sensors Control Computer Sensors

Control Actuator





Combination of active and passive devices. It is observed theminimization of the restraints and limits related with each oneof the devices working alone.



Control Actuator

PD





Belong to a certain class of active devices inwhich the external energy requests are verylow. Present the great adaptability of theactive devices and the great fiability of thepassive devices.



Control Actuator

PD



33 LNEC EXPERIENCE IN ANTILNEC EXPERIENCE IN ANTI--SEISMIC SEISMIC

SYSTEMSSYSTEMS




CONTENTS


>> ECOEST II (U. ECOEST II (U. BasilicataBasilicata, , ItalyItaly))

��TITLE:TITLE: RC frames reinforced with energy dissipation devices

ooOBJECTIVES:OBJECTIVES: Study the effectiveness of certain passive control techniques applied to the rehabilitation of existing reinforced concrete structures�DESCRIPTION OF THE EXPERIMENTAL PROGRAM:

� Two models of a 4 floor spatial span built at scale (1:4) and designed without specific seismic resistance (vertical loads) according to the Italian regulation prior to 1970

� Seismic tests of reinforced concrete structures, strengthened with bracing systems (energy dissipation devices included)

LNEC EXPERIENCE IN ANTI-SEISMIC SYSTEMS




ooBRACING SYSTEMSBRACING SYSTEMS

�Metallic braced elements with energy dissipation devices (metallic dampers and shape memory alloys) placed in the initial RC structure in different levels and directions

�According to the larger dimension (x direction) the bracing elements were diagonally disposed one by floor in alternate spans. In y direction too





ooBRACING SYSTEMSBRACING SYSTEMS



Direzione X Direzione Y



ooBRACING SYSTEMS BRACING SYSTEMS –– MetallicMetallic DampersDampers



��Metallic elements Metallic elements

with steel dissipative with steel dissipative

units (device units (device

composed of four composed of four

double mild steel double mild steel

layers with a certain layers with a certain

shape and variable shape and variable

dimensions) in the dimensions) in the

different floors and different floors and

directions, fixed to directions, fixed to

the brace elementthe brace element

��Energy dissipation Energy dissipation



ooRESULTS RESULTS –– MetallicMetallic DampersDampers



�� High capacity of energy High capacity of energy

dissipation by plastic dissipation by plastic

deformation of steel deformation of steel

without loss of rigidity without loss of rigidity

or strength of the or strength of the

bracing elementbracing element

�� Dissipation mechanism Dissipation mechanism

is a result of the is a result of the

inelastic deformation of inelastic deformation of

the metalthe metal Asymmetrical masses

Symmetrical masses



ooBRACING SYSTEMS BRACING SYSTEMS –– ShapeShape MemoryMemory AlloysAlloys



��Use of metallic Use of metallic

leagues with form leagues with form

memory (energy memory (energy

dissipation dissipation

characteristics and characteristics and

capacity of recovery capacity of recovery

the elastic rigidity)the elastic rigidity)

��Metallic elements Metallic elements

associated to the associated to the

wire device in nickelwire device in nickel--

titanium (good titanium (good

durability, high durability, high



ooRESULTS RESULTS –– ShapeShape MemoryMemory AlloysAlloys



�� Considerable dissipating ability, Considerable dissipating ability,

being notable the recovery of being notable the recovery of

elastic characteristics of the elastic characteristics of the

materials usedmaterials used

�� After a high number of cycles with After a high number of cycles with

significant dissipation, the bracing significant dissipation, the bracing

elements practically do not show elements practically do not show

permanent displacements permanent displacements

(recovering in the beginning of (recovering in the beginning of

each new cycle the rigidity and each new cycle the rigidity and

the initial elastic resistance)the initial elastic resistance)

Symmetrical masses

Asymmetrical masses

>> NEFOREEE2 NEFOREEE2

��TITLE:TITLE: Controlled Testing in the Non-Linear Range

ooOBJECTIVESOBJECTIVES

�� StudyStudy ofof thethe behaviourbehaviour ofof twotwo differentdifferent typestypes ofof

energyenergy dissipationdissipation devicesdevices ((viscoelasticviscoelastic dampersdampers andand

viscousviscous fluidfluid dampersdampers))

ooGeometryGeometry ofof thethe modelsmodels

�� BracingBracing systemssystems (K (K andand X X shapeshape) ) allowingallowing thethe

placementplacement ofof passivepassive dissipationdissipation devicesdevices andand a a

natural natural frequencyfrequency range range inin accordanceaccordance withwith thethe ST ST

andand RWRW

�� 3D 3D FrameFrame: 3m longitudinal, : 3m longitudinal, 2.45m 2.45m transversetransverse, 4.5m , 4.5m

de de columncolumn heightheight andand 3.0m 3.0m betweenbetween slabsslabs





ooGeometryGeometry ofof thethe modelsmodels



315

0

Ø13

250

250250

140

75

110

125 125

125

635

250 250

3400

2900

250250

Ø13

125

125

250 250

125140

125

50

75

90

180

125

125

351

252

50

250

166

0

293

0

635

250

110

110

510

2900

2160

3180

35

257

0

250

250

250

125

250

250

125

125

510

110

25 35

2542

25

3060

75390

5535

125125125

125

27,

5

75

27,

5

125125 125

3000

3400

2900

125125

125125

125 125125 125

125 125125125

125125 125

12575

Ø13

262

12

300

12

50

65

2570

1693

76 180 141

25

125

201

262

338

490

1693

262

3545

100

35

160

400

35

25 1000

25

100

12

300

01

500

125125

125

27,

52

7,5 35

125125

125125 125

3150

2750

2570

125125

125125

125 125125 125

12535

125125

125125

Ø13

2.2

50

4.5

90

4.5

76

125

125

125

250

125



ooDorkaDorka DissipationDissipation DevicesDevices



��DevelopedDeveloped byby SchmidtSchmidt

andand DorkaDorka

��Innovative device with Innovative device with

a steel squared tubular a steel squared tubular

section with the section with the

dissipation mechanism dissipation mechanism

based in the based in the elastoelasto--

plastic plastic behaviourbehaviour of of

steelsteel

��EasyEasy replacementreplacement ofof

thethe devicedevice andand

reproductionreproduction ofof thethe

A8



ooJarrettJarrett DissipationDissipation DevicesDevices



��CurrentCurrent industrial industrial

devicedevice

��EnergyEnergy dissipationdissipation

basedbased inin thethe

compressioncompression ofof a a

viscovisco--elasticelastic silicone silicone

fluidfluid

��AllowAllow thethe dissipationdissipation

ofof a a partpart ofof thethe kinetickinetic

energyenergy generatedgenerated

duringduring a a seismicseismic actionaction

��ApplicationsApplications ofof thesethese

DRW n°022575

A8

A6

DRW n°022575

A7 DRW n°022575



ooRESULTS: Modal RESULTS: Modal AnalysisAnalysis

�� 1.5% 1.5% withoutwithout dissipationdissipation devicesdevices

�� 3.0% 3.0% withwith DorkaDorka DissipationDissipation devicesdevices

�� 7.5% 7.5% withwith JarrettJarrett DissipationDissipation devicesdevices



��Modal Modal frequenciesfrequencies

obtainedobtained usingusing FRF FRF

andand PeakPeak PickingPicking

��OneOne singlesingle modemode

��DampingDamping estimatedestimated

for for allall modelsmodels::

0

2

4

6

8

10

12

cat00 cat01 cat02 cat03 cat04 cat05 cat06 cat07 cat08 cat09 cat10Test

Freq [Hz]

Evolution of the experimental frequencies



ooRESULTS: RESULTS: DorkaDorka DissipationDissipation DevicesDevices



ElCentro 0.2g EC8 0.2g EC8 0.6g EC8 0.8g EC8 1g NW top accel trans [g] 0.26 0.32 1.02 1.16 1.39 SW top accel trans [g] 0.27 0.37 1.11 1.25 1.51 Vert mass accel (CM) [g] 0.014 0.020 0.47 1.18 1.26 NW top column displ [mm] 63.34 26.23 78.92 104.40 110.20 SW top column displ [mm] 63.45 26.49 80.57 106.69 133.85 FNorth [kN] 10.49 14.47 42.87 49.43 56.98 FSouth [kN] 12.59 17.47 47.41 58.22 60.12 Displ North [mm] 0.27 0.40 1.03 1.75 4.02 Displ South [mm] 0.38 0.36 1.26 2.51 5.49

•0.6g

•1.0g



ooRESULTS: RESULTS: JarrettJarrett DissipationDissipation DevicesDevices



•0.6g

•1.0g

ElCentro 0.2g EC8 0.2g EC8 0.6g EC8 0.8g EC8 1g NW top accel trans [g] 0.37 0.27 0.89 1.50 1.70 SW top accel trans [g] 0.33 0.30 0.87 1.58 1.74 Vert mass accel (CM) [g] 0.007 0.009 0.05 0.09 0.13 NW top column displ [mm] 63.04 28.27 85.57 107.12 102.23 SW top column displ [mm] 63.35 28.65 86.30 114.06 133.63 FNorth [kN] 6.30 8.21 20.89 35.63 50.54 FSouth [kN] 6.76 8.63 21.63 39.48 54.81 Displ North [mm] 1.96 1.99 10.61 11.71 12.55 Displ South [mm] 1.95 1.89 10.33 12.00 12.48





44 LNEC FUTURE DEVELOPMENTS IN ANTILNEC FUTURE DEVELOPMENTS IN ANTI--

SEISMIC SYSTEMSSEISMIC SYSTEMS


CONTENTS


> Tuned Liquid Dampers (TLDs) have been receiving particular attention from the international scientific comunity since the90s as a simple but effective way of reducing the buildingsresponse when subjected to dinamic actions

> A considerable number of these devices has been instaled inareas with higher seismic risk and low frequency constructions(towers, bridges …)

> Increasing interest in the use of these devices for currentbuildings

> Portuguese constructions are increasing in height andbecoming more flexible (with the reducion of the fundamental frequency)

LNEC FUTURE DEVELOPMENTS IN ANTI-SEISMIC SYSTEMS


> Study of less expensive and easy to mantain solutions (goodrelation cost-benefit)

> Increasing in the area of research activities (mainlyexperimental) in order to better understand the maincharacteristcs and benefits of new energy dissipation devicessolutions



Study on the effectiveness of Tuned Liquid Dampers(TLDs) for reducing dynamic vibrations in buildings

- LNEC Research Project and PhD thesis -



> Study on the effectiveness of Tuned Liquid Dampers (TLDs) for reducing dynamic vibrations in buildings

�Historical evolution and state of the art in the area ofseismic protection devices

�General characterization of the existing Seismic Protection Devices (with particular interest in the Energy Dissipation Devices) and basic principles of functioning

�Practical applications of Energy Dissipation Devices inexisting structures




�Analytical simulations (preview and validate theexperimental results)

o Use of the free acess software CLAWPACK (Conservation LAWsPACKage) developed by the Washington University

o Solving of 1D, 2D and 3D linear and non-linear problems




�Experimental program

o General characterization of the Tuned Liquid Dampers to beexperimentally tested

o Testing set-up

� TLD – 1GDL

� SDOF structure + TLD – 2 GDL

o Parametric study (water height, excitation, TLD shape, liquid, presenceof suspension particles, mass ratio, …)

o Results analysis




�Experimental program




�Comparison between the results obtained for the differentexperimental programs previously developed in LNEC andthe results obtained for TLDs

o Metallic Dampers (ECOEST2)

o Shape Memory Alloys (ECOEST2)

o Viscoelastic Dampers (NEFOREEE)

o Viscous Fluid Dampers (NEFOREEE)

�Definition of recomendations related with the use of EnergyDissipation Devices in new or existing structures







55 CONCLUSIONSCONCLUSIONS

CONTENTS


> The implementation of seismic protection devices to Portugal (as a country of moderated seismic risk) ischallenging because it allows the reduction of the direct andindirect consequences related with the seismic actions

> In many cases (TLDs) it may be achieved a profitable cost-benefit relation

> Despite the progresses in the research is important theawareness of all the entities involved in the process(government, construction companies and final users)

> The generalization in the use of innovative seismicprotection devices will allow the reduction of the seismicrisk related with the existing constructions

CONCLUSIONS


innovative anti -seismic systems: lnec experimental … · 2009. 2. 4. · anti-seismic systems...

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