Workshop: October 31, 2014 - Departamento de … · Workshop: October 31, 2014 FCT/UNL, LNEC, EP,...

Dynamic Performance Assessment & Rehabilitation of Structures

Workshop: October 31, 2014

FCT/UNL, LNEC, EP, IST () UNIC/DEC/FCT/UNL 1 / 19

Southern part of Portugal - region with significant seismic activity

(PGA ≃ 0.2 . . . 0.25g)

Recorded seismic events between 1970 and 2007 Mainland hazard maps for an exceedance probability of 10% in 50 years


Project PTDC/ECM/117618/2010 - launched in 2012

Assess the unseating vulnerability of several footbridges in the Southern part of Portugal.


Why bother with footbridge structures?

Lifelines interruption due to natural hazards can have major economic and social impacts, leading tomuch higher losses than the value of the damaged infrastructures.

Although footbridges are not usually considered as critical lifeline structures, their collapse during anatural hazard such an earthquaque can be critical, as it might cause severe lifelines interruption.


Example: potential risk on EN 125-10 Portuguese motorway

Several pedestrian crossing located in a particularly sensitive area (Faro airport and railways station,3 hospitals, 2 fire departments, large shopping center, a large university and several schools).

Simply supported reinforced concrete footbridges(span 26. . . 34 m; vertical clearance 5.2. . . 5.6 m).


Footbridges - typical design details

Deck cross section Deck/pile connection Main pile

◮ Deck: two 1.2m height I-shaped prestress girders, connected by a 0.12m thick deck slab;

◮ Connection main girders and piles: two Φ20mm steel dowels and a neoprene bearing pad;

◮ Main piles: precast reinforced concrete elements with variable cross section (0.6× 0.5m2 to1.0× 0.5m2) and superficial precast foundations;

◮ Access ramps/stairs: precast reinforced concrete ribbed slabs.


Footbridges - typical design details

Single-span support detail Multiple-span support detail

◮ In single-span footbridges, the seating length of the deck is 0.50 m ;

◮ In multiple-span footbridges, the seating length of the decks is 0.24 m.


Modal identification campaign - 17 footbridges


Ambient Vibration Tests - 15 minutes at 100 Hz

SYSCOM MR2002-CE vibration monitoring systems equipped

with MS2003+ triaxial velocity sensors

ARTeMIS(operational modal analysis software)

EFDD: singular values of the spectral density matrices

SSI-UPC: stabilization diagram


Web database


Updated numerical models (FEM and AEM - OpenSees, SismoStruct ,ELS)

Optimization parameters:

◮ the bending stiffness of the main girders;

◮ the stiffness of the connections between the piles and the rigid foundations;

◮ the stiffness of the neoprene elastomeric laminated bearings (including the steel dowelconnectors) between the main girders and the piles.

PP3141 (1 span)

PP 2757 (2 spans)

PP2787 (3 spans)


Complex modeling of the dowel connection

corbel reinforcement

bearing pad

dowels

mesh refinementmain girder

main pier

0.00 0.25 0.50 0.75 1.00

Deck displacement [m]

20

40

60

80

0

Dow

el s

hear

forc

e [k

N]

A − failure of the dowelsB − collapse of the piers

Dowels Φ20 MC2010∗ BS8110Maximum dowel shear force [kN] 56.19 94.20

∗ Dowel effect included


Typical seismic response to design earthquake (PGA 0.3g)

NO UNSEATING VULNERABILITY−0.06

−0.04

−0.02

0

0.02

0.04

0.06

0.08

0.1

0 20 40 60 80 100

Dec

k/pi

le r

elat

ive

disp

lace

men

t [m

]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]

Horizontal displacement of the pile top [m]

−150

−100

−50

0

50

100

150

−0.1 −0.05 0 0.05 0.1

Dow

els

shea

r fo

rce

[kN

]

Deck/pile relative displacement [m]


Cascading aftershocks scenario

Cascading aftershocks (PGA 0.3g main shock, 0.2g foreshock and aftershock)

POTENTIAL UNSEATING VULNERABILITY−0.06

−0.04

−0.02

0

0.02

0.04

0.06

0.08

0.1

0 20 40 60 80 100

Dec

k/pi

le r

elat

ive

disp

lace

men

t [m

]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]


−150

−100

−50

0

50

100

150

−0.1 −0.05 0 0.05 0.1

Dow

els

shea

r fo

rce

[kN

]

Deck/pile relative displacement [m]


Seismic response of the retrofitted structure - 4 STEEL rods (0.4m, Φ10mm)

Design earthquake (PGA 0.3g)


−0.03

−0.02

−0.01

0

0.01

0.02

0.03

0.04

0 20 40 60 80 100

Dec

/pile

rel

ativ

e di

spla

cem

ent [

m]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]


−150

−100

−50

0

50

100

150

−0.04 −0.03 −0.02 −0.01 0 0.01 0.02 0.03 0.04

Axi

al fo

rce

[kN

]

Axial displacement [m]


MILD UNSEATING VULNERABILITY−0.04

−0.03

−0.02

−0.01

0

0.01

0.02

0.03

0.04

0 20 40 60 80 100

Dec

/pile

rel

ativ

e di

spla

cem

ent [

m]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]


−150

−100

−50

0

50

100

150

−0.04 −0.03 −0.02 −0.01 0 0.01 0.02 0.03 0.04

Axi

al fo

rce

[kN

]



Seismic response of the retrofitted structure - 4 SMA rods (0.4m, Φ11mm)

Design earthquake (PGA 0.3g)


−0.03

−0.02

−0.01

0

0.01

0.02

0.03

0.04

0 20 40 60 80 100

Dec

/pile

rel

ativ

e di

spla

cem

ent [

m]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]


−150

−100

−50

0

50

100

150

−0.04 −0.03 −0.02 −0.01 0 0.01 0.02 0.03 0.04

Axi

al fo

rce

[kN

]




−0.03

−0.02

−0.01

0

0.01

0.02

0.03

0.04

0 20 40 60 80 100

Dec

/pile

rel

ativ

e di

spla

cem

ent [

m]

Time [s]

−600

−400

−200

0

200

400

600

−0.1 −0.08 −0.06 −0.04 −0.02 0 0.02 0.04 0.06 0.08 0.1

Bas

e sh

ear

forc

e [k

N]


−150

−100

−50

0

50

100

150

−0.04 −0.03 −0.02 −0.01 0 0.01 0.02 0.03 0.04

Axi

al fo

rce

[kN

]



Large scale experimental tests - LNEC

fixed to the shaking platform

pier (6.3 m height)

deck (2x6.4 m span)

fixed to reaction walls

fixed to reaction walls Triaxial shaking platform

◮ Dimensions: 4.6 × 5.6 m

◮ Frequency range: 0.1 to 40 Hz

◮ Stroke: 400 mm

◮ Horizontal acceleration: 18.75 m/s2

◮ Model weight: 392 kN

SMA damping device


Proposed prestress SMA damping device


Dynamic Performance Assessment & Rehabilitation of Structures

Workshop: October 31, 2014


Workshop: October 31, 2014 - Departamento de … · Workshop: October 31, 2014 FCT/UNL, LNEC, EP,...

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Transcript of Workshop: October 31, 2014 - Departamento de … · Workshop: October 31, 2014 FCT/UNL, LNEC, EP,...