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2016 Mw7.8 Ecuador Earthquake: Relevance to NYC & US Critical InfrastructureEERI-NYNE and ASCE Met Section Infrastructure Group Mini-Symposium

Unreinforced Masonry BuildingsSeismic Risk andMitigation Technologies

Prof. A. Whittaker, U. BuffaloGSMT, New York City

May 30, 2017Seismic Performance of the SeismicallyIsolated Los Caras Bridge

Dr. Enrique MoralesProfessor and Chair of the Department of Civil Engineering at ESPE

UniversityMarcelo Romo M.S.

Professor of ESPE Universityand Consultant of Ecuador Army Corps of Engineers

INTRODUCTION AND SEISMIC HAZARDEcuador Location · Seismic Hazard · Site-Specific Ground Motions

LOS CARAS BRIDGE DESCRIPTION AND SEISMIC DESIGNCRITERIA

Seismically Isolated Bridges · Project Description · Structural Systems Selected · Seismically IsolatedStructure Design Criteria

SEISMIC PERFORMANCE OF ISOLATED SYSTEMRelevant Recorded Ground Motions · Seismic Performance of the Isolation System

SEISMIC PERFORMANCE OF NON-ISOLATED SYSTEMSeismic Protection System Components · Displacement Control Devices · Seismic Performance of

Displacement Control Components

MONITORING AND MAINTENANCEIsolation System · Non-Isolation System

SEISMIC PERFORMANCE IN OTHER BRIDGES

ACKNOWLEDGEMNT AND CONCLUSIONS

OUTLINE

Ecuador

(ESPE 2016)

(Source ephotopix)

Seismic Hazard of Ecuador

(Yepes 2016)

(Egred 2009)

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Geodynamic Setting of Ecuador, theGalapagos Islands and the Carnegie

Ridge

(Toulkeridis 2013)

Response Spectrum and Code-Based Design Spectra NEC-2015

QUITO

Pedernales

MantaPortoviejo

Chone

Esmeraldas

GuayaquilGround motions provided by the Seismology Department, Instituto Geofísico, Escuela Politecnica Nacional, Ecuador with details intheir report Singaucho, J., Laurendeau, A., Viracucha, C., Ruiz, M. (2016). “Observaciones del Sismo del 16 de Abril de 2016 deMagnitud Mw 7.8”

The Ecuador 2016 Muisne Earthquake

Seismically Isolated Bridges in Ecuador

North Bridge 1 Esmeraldas (GPS: 0°58'4.31"N;79°38'42.34"W)

The Los Caras Bridge(GPS: 0°36'33.6"S, 80°24'58.7"W)

152 Triple Friction Pendulum BearingsThere are three seismically isolated bridges

(Total 36 Triple Friction Pendulum Bearings)

Source Ecuador Army Corps of Engineers (EACE) Source Aguiar R

Seismically Isolated Bridges in Ecuador

San Pedro Bridge(GPS: 0°13'10.90"S, 78°25'29.56"W)

El Chiche Bridge(GPS: 0°12'40.88"S, 78°22'9.16"W)

4 Simple Friction Pendulum Bearings 8 Simple Friction Pendulum Bearings

Source El Universo Source Google Earth

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Seismic Protection Industry

Japan Society of Seismic Isolation

Location of the Seismically IsolatedLos Caras Bridge

Source (EACE)

BAHIA DECARAQUEZ

SAN VICENTE

Chone RiverEstuary

BahíaAccess

CentralSection

San VicenteAccess

Project Description

Source (EACE)

BAHIA DE CARAQUEZ

SAN VICENTE

Chone River Estuary

Central SectionBahía Access

Los Caras Bridge

San VicenteAccess

Site-Bridge

Source (EACE)

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Lamp

Road of Bicycle

Tubular PileASTM A 588

Slab

Column

Footing

Girder

13.20 m

Base isolation

Parapet

Pier

FOUNDATION

SUBSTRUCTURE

SUPERSTRUCTURE

FINISHES

N+11.95

N+9.288

N+7.688

N+2.330

N+0.68

N+0.00

TYPICAL SECTION OF THE PIERTYPICAL SECTION OF THE PIER

Source (EACE)

Structural System Selected

• Base Isolation on Top of Piles andUnder the Bridge DeckTriple Friction Pendulum (TFP) byEarthquake Protection Systems(EPS)

• Frictional Pile Deep Foundation

• Pile Driving Analyzer (PDA) forTesting Piles

Source (EACE)

• Pier Stability ThroughRedundant Pile Linesand Redundant PierFrames

Structural System Selected

• Bridge Deck Continuity: 180 m (4 spans) and 90 m (2 spans)

Source (EACE)

Soil Condition

Source (EACE)

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• GLOBAL• Seismic System and Structural

Elements Above Isolation SystemR=1.0

• Seismic System and StructuralElements Below Isolation System

R=1.25

• SUPERSTRUCTURE• Movement Synchronizers: Local

Design• Large Displacement Seismic

Joints: Local Design• SUBSTRUCTURE

• Basic Ductility Detailing• Frictional Pile Deep Foundation

Seismically Isolated Structure DesignCriteria

Source (EACE)

Seismically Isolated Structure –DesignCriteria

• SEISMIC DESIGN HYPOTHESIS• Seismic Hazard Local Study• Seismic Provisions (CEC 2002)• Peak Rock Acceleration (from

seismic hazard map and fromseismic hazard study):ar = 0.40 g; ar = 0.42 g

• Peak Ground Acceleration:ag = 0.80 g; ag = 0.84 g

Source (EACE)

Isolator Idealization for Design

DE MCE

Target Properties

Source (EACE)

Isolator Geometry and BearingCapacities (FPT8836/14-12/10-7)

· Bearing Capacities Lateral Displacement Capacity = 23.0 inches +/- 0.3 inches.

· Average Vertical Dead Load = 600 kips used for bearing property tests.

· Maximum Vertical D+L Load Capacity = 1200 kips maximum.

· Maximum Vertical D+L+E Load Capacity = 1900 kips maximum.

· Maximum vertical load capacities are based on concave plates bearing against 5000psi concrete.

· Minimum Rotation Capacity = +/- 2 deg.

· Ri = Radius of curvature sliding surface i.

· µi = Friction coefficient of sliding surface i.

· hi = Height of sliding interface i.

· di = Displacement capacities of sliding interface i.

(Constantinou 2011)

Earthquake Protection Systems (EPS)

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Prototype Bearing Real-Time DynamicTest Program

(Total 152 Bearings)

Earthquake Protection Systems (EPS)

Relevant Recorded Ground Motions

-1500

-1000

-500

0

500

1000

0 5 10 15 20 25 30 35 40 45

-400-300-200-100

0100200300400500600

0 5 10 15 20 25 30 35 40 45

E-W Pedernales Ground Motion (PGA = 1.43 g)

N-S Manta Ground Motion (PGA = 0.53 g)

cm/s2

cm/s2

T(sec)

T(sec)

During the Ecuador 2016 Muisne Earthquake

Seismic Performance of the IsolationSystem

During the Ecuador 2016 Muisne Earthquake

Seismic Performance of the IsolationSystem

0

10

20

30

40

50

60

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Total Displacement(cm) of the TFPcm

Piers

Source (EACE)

During the Ecuador 2016 Muisne Earthquake

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• Seismic Movement Synchronizers –Shock Absorbers

Seismic Protection System Components

Source (EACE)

• Large Displacement Seismic Joints and Joint Seals

Seismic Protection System Components

• Seismic Movement Synchronizers

Seismic Protection System Components

Source (EACE)

• Seismic Large Displacement Joints and Joint Seals

Source (EACE)

Seismic Performance of DisplacementControl Components

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Monitoring and Maintenance of IsolationSystem

Source (EACE)

Bolts

BoltsGrout

• Seismic Movement Synchronizers• Bolt rust• Impact traces in neoprene• Superficial overheating

Source (EACE)

Monitoring and Maintenance of IsolationComponents

• Large Displacement Seismic Joint and Joint Seal• More than 35 cm displacement in any

direction• Vertical displacement

Source (EACE)

Monitoring and Maintenance of IsolationComponents

Seismic Performance of Non-IsolatedAccesses

• Longitudinal NeopreneShock Absorbers

• Steel Bar VerticalAnchorages

Source (EACE)

Displacement Control Devices in Non-Isolated Accesses

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• Transversal Seismic Shear keys

Source (EACE)

• Neoprene Bearings in San Vicente Access

Seismic Performance of Non-IsolatedComponents

Seismic Performance inOther Bridges

• Esmeraldas Bridges (PGA = 0.23 g) /Major displacements (D < 15 cm)

Source (EACE)

• Ecuador Army Corps of Engineers.

• ESPE University.

• Buffalo University.

• Earthquake Protection Systems (EPS).

• Professor Michael Constantinou.

• General Pedro Mosquera, Jorge Landazuri andFrancisco Beltran.

AcknowledgementContributions are gratefully acknowledged:

The Las Caras Bridge at 2 km length is the longest bridge in Ecuador.

It stretches across the Bahia de Caraquez'es bay and was significantly affected by the April16, 2016 M7.8 earthquake offshore the west coast of northern Ecuador.

It is seismically isolated with a triple FP isolation system designed to have a displacementcapacity of 585 mm.

The bridge remained functional during and after the earthquake and it represented asignificant link in reaching the most affected cities by the earthquake for providing aid.

Records of ground shaking at stations before and after the bridge in the direction ofpropagation of the earthquake rupture show peak ground accelerations between 0.5g and1.4g.

It was evident that was significant variability in the ground shaking from pier (within about 120m) as the bearing displacement recorded varied from about 100 mm to about 650 mm. Thiswas without doubt the largest ever recorded motion of a seismically isolated structure.

Conclusions

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The Mw 7.8 Earthquake in Muisne, Ecuador in 2016 produced large transversal movementson seismic joints in Los Caras Bridge, up to 32 cm, equivalent to 90% of DE intensity level.

Seismic joints designed for Los Caras Bridge worked as expected.

Vertical movements of seismic joints proved to be important for major earthquakes.

Synchronizers employed in isolated bridges, designed according to a conceptual methodbehaved adequately under a major Mw 7.8 earthquake, with ground accelerations similar to aDE earthquake.

It demonstrated the significance of a proper philosophy for design that ensures a smallenough risk of damage and collapse.

Conclusions