Workshop: Seismic Protection of Monumentsecpfe.oasp.gr/sites/default/files/files/Thomas N_...

“Utilization of EPPO Strong Motion Network Records for the Determination of

Rational Seismic Loads for Masonry Monuments ”

Thomas N. Salonikios

Senior Researcher, EPPO

Workshop:

“Seismic Protection of Monuments ”

For Reinforced Concrete the

Seismic Codes, suggest:

δviscous =5%

For Unreinforced Masonry the

Seismic Codes, suggest:

δviscous =5%

δviscous =5%

δviscous >5%

STEPS OF THE PRESENTATION

•Exact Phenomenon – Earthquake Records

•Elastic Analysis of Building Models and Inelastic Analysis of Plane Frames

•Literature Review

•Conclusions

•Proposals

Four strong earthquakes struck Southern and Western Peloponnesus during

three years (2006-2008). These earthquakes were recorded by ITSAK

strong motion accelerograph network. ITSAK research personnel visited

stricken areas, the masonry monuments were inspected and (among others)

damages were recorded.

The base as well as spectral accelerations had variable scale. The damages

that were observed varied from hairline cracks to partial collapses of

monuments.

Due to the aforementioned variation of accelerations and damages is

attempted the correlation of the developed damages with the spectral

accelerations of each earthquake.

Finally these spectral accelerations (normalized values) are correlated with

the design accelerations of seismic codes and with capacity accelerations

that the finite element models of masonry buildings (elastic analysis) and

plain frames (inelastic analysis) can stand.

EPPO National Accelerograph Network

Kythera Earthquake

Kythera earthquake was of magnitude Μ6.9, happened 8/1/2006 at 13:34 local

time, Southern Peloponnesus, epicenter depth 66km, classified as intermediate

depth earthquake.

Leonidio Earthquake

Leonidio earthquake was of magnitude Μ6.5, happened 6/1/2008 at 07:14 local

time, Southern Peloponnesus, epicenter depth 80km, classified as intermediate

depth earthquake.

Koroni Earthquake

Koroni earthquake was of magnitude Μ6.7, happened 14/2/2008 at 12:09 local time,

Southern Peloponnesus, epicenter depth 35km, classified as surface earthquake.

Achaia – Ilia Earthquake

Achaia – Ilia earthquake was of magnitude Μ6.5, happened 8/6/2008 at 12:25 local

time, North-Western Peloponnesus, epicenter depth 31km, classified as surface

earthquake.

Description of masonry buildings in Peloponnesus

α) One or two storey buildings with mud bricks

β) One or two storey buildings with stone bricks and clay or lime mortar.

Storehouses or residential buildings at villages.

γ) One to three storey buildings with stone and/or clay bricks and lime mortar.

These buildings are located at the historic centers in Peloponnesus towns.

δ) Temple buildings. Are constructed by the use of stone or clay bricks and lime

mortars. There is an important variety of the structural systems that were applied.

ε) Other structures. Archaeological ruins with stone or clay bricks, without or with

mortar.

`

Source: Division of Seismology of ITSAK

Kythera EQ 8/1/2006 (Μ6.9)

Response of masonry buildings during Kythera EQ

During this EQ were observed damages to masonry buildings. Damages were

observed at the upper storey of residential buildings and at the bell towers of

some temples.

Σεισμός Κορώνης 14/2/2008 (Μ6.7)

Leonidio EQ 6/1/2008 (Μ6.5)


Leonidio EQ: Similarly with Kythera EQ were observed damages to masonry

buildings. Damages were observed at the upper storey of residential buildings and

at the bell towers of two temples. At the location, where the EQ was recorded, were

not observed any damages.

Koroni EQ: No damages.

Achaia – Ilia EQ 8/6/2008 (Μ6.5)


Response of masonry buildings during Achaia – Ilia EQ

-150

-100

-50

0

50

100

150

0 10 20 30 40

ΕΙΜΟ ΚΤΘΗΡΩΝ, ΚΑΣΑΓΡΑΦΗ ΑΓ. ΝΙΚΟΛΑΟ "L"

cm/sec

2

-100

-80

-60

-40

-20

0

20

40

60

80

100

0 10 20 30 40 50 60

ΕΙΜΟ ΚΟΡΩΝΗ, ΚΑΣΑΓΡΑΦΗ ΚΟΡΩΝΗ "L"

cm/sec

2

-200

-150

-100

-50

0

50

100

150

200

0 10 20 30 40 50

ΕΙΜΟ ΑΥΑΪΑ - ΗΛΕΙΑ, ΚΑΣΑΓΡΑΦΗ ΠΤΡΓΟ "T"

cm/sec

2

-200

-150

-100

-50

0

50

100

150

200

40 50 60 70 80 90 100

ΕΙΜΟ ΑΥΑΪΑ - ΗΛΕΙΑ, ΚΑΣΑΓΡΑΦΗ ΒΑΡΘ. "T"

cm/sec

2

Kythera EQ, recorded

at Agios NikolaosKoroni EQ, recorded

at Koroni

Achaia – Ilia EQ,

recorded at Pyrgos

Achaia – Ilia EQ,

recorded at

Vartholomio

0.00

0.15

0.30

0.45

0.60

0.75

0.90

0 0.4 0.8 1.2 1.6

Sa(g)

T(sec)

ΕΙΜΟ ΚΤΘΗΡΩΝ

ΕΝΣΟΝΗ ΓΡΑΜΜΗ ΚΑΣΑΓΡΑΦΗ ΑΓ.

ΝΙΚΟΛΑΟ ΛΑΚΩΝΙΑ L,T

ΛΕΠΣΗ ΓΡΑΜΜΗ ΚΑΣΑΓΡΑΦΗ ΚΤΘΗΡΑ L,T

0.00

0.15

0.30

0.45

0.60

0.75

0.90

0 0.4 0.8 1.2 1.6

Sa(g)

T(sec)

Koroni EQ

0.00

0.15

0.30

0.45

0.60

0.75

0.90

0 0.4 0.8 1.2 1.6

Sa(g)

T(sec)

ΕΙΜΟ ΑΥΑΪΑ - ΗΛΕΙΑ

ΛΕΠΣΗ ΓΡΑΜΜΗ ΚΑΣΑΓΡΑΦΗ

ΠΤΡΓΟΤ L,T

ΕΝΣΟΝΗ ΓΡΑΜΜΗ ΚΑΣΑΓΡΑΦΗ

ΒΑΡΘΟΛΟΜΙΟΤ L,T

Kythera EQ

Achaia - Ilia EQ

Spectral Accelerations

EQSaomax Samax T 2.5*Ao/1.5 (2/3)*Samax

(1) (2) (3) (4)=2.5*0.24/1.5 (5)=2/3*(2)

Koroni 0.07g 0.31g 0.28sec 0.6g/1.5=0.4 0.20g

Kythera 0.15g0.65g

0.46g

0.55sec

0.32sec0.6g/1.5=0.4

0.43g

0.31g

Achaia -

Ilia0.21g 0.87g 0.18sec 0.6g/1.5=0.4 0.57g

Spectral Accelerations

EQSaomax Samax T 2.5*Ao/1.5 (2/3)*Samax

(1) (2) (3) (4)=2.5*0.24/1.5 (5)=2/3*(2)

Koroni 0.07g 0.31g 0.28sec 0.6g/1.5=0.4 0.20g

Kythera 0.15g0.65g

0.46g

0.55sec

0.32sec0.6g/1.5=0.4

0.43g

0.31g

Achaia -

Ilia0.21g 0.87g 0.18sec 0.6g/1.5=0.4 0.57g

No cracks

Cracks

Extended cracks + few partial

collapses





•Conclusions

•Proposals

Considered Finite Element Models

Common characteristics of modeled buildings:

•Masonry buildings

•Were subjected to strong EQs

•Remain and operate till nowadays with light and repairable damages

•When are subjected to modern code seismic loads, results partial or total

collapse. This situation is not confirmed due to the existence and operation

of the buildings till nowadays.

•These buildings can stand the seismic loads of 1984 Greek Seismic Code

“0.08g – 0.16g” when these loads are applied as constant horizontal loads

in inverted triangular shape.

Justification of equivalent seismic load coefficient “25%*g” :

“Equivalent” seismic load coefficients

FRAME TYPE 1 BAY 7 BAY

LOAD TYPE LOAD, MODE ACCLOAD,

MODEACC

SAP2000 Nonlinear

Frame Elements0.26g 0.24g

Continuous Model 0.30g 0.36g 0.47g 0.55g

Discrete Model 0.25g 0.31g 0.29g 0.33g

“Equivalent” seismic load coefficients for the

considered model types and various loading schemes.





•Conclusions

•Proposals

Justification of equivalent dumping factor “20%” :

According Magenes and Calvi (1997) the equivalent “hysteretic + viscous” dumping

may be between 15% and 64% in relation with the mechanism that fails. Lower

values for flexural response and higher values for sliding shear response.

According Tomazevic and Weiss (1994) the equivalent dumping is shown at the

following figures and resulted from tests at two specimen buildings that were

constructed under 1:5 scale and were tested at the seismic table:

According Bothara et al.

(2010) the effective

dumping as resulted

from the test of a real

scale masonry building

at the seismic table, is

given at the following

table:

According Ahmad et al (2010) the hysteretic dumping at the masonry structures

that are subjected to earthquakes are given in relation with the achieved ductility, as

follows:


•Exact Phenomenon: Earthquake Records – Monument Response


•Targeted Literature Review

•Conclusions

•Proposals





•Conclusions

•Proposals

0.00

0.15

0.30

0.45

0.60

0.75

0.90

0 0.4 0.8 1.2 1.6

Sa(g)

T(sec)


ΚΑΣΑΓΡΑΦΗ ΒΑΡΘΟΛΟΜΙΟΤ

0.44g

0.33g

0.23g

δ=0.05

δ=0.10

δ=0.20

Achaia - Ilia EQ

Vartholomio Record

0.00

0.15

0.30

0.45

0.60

0.75

0.90

0 0.4 0.8 1.2 1.6

Sa(g)

T(sec)


ΚΑΣΑΓΡΑΦΗ ΠΤΡΓΟΤ

0.57g

0.39g

0.25g

δ=0.05

δ=0.10

δ=0.20

Pyrgos Record

Achaia - Ilia EQ

•From literature review:

•From parametric analyses of

masonry frames and buildings

Inelastic:

Elastic:

•From the postprocessing of

records where only local

cracks or local damages were

observed on monuments and

no collapses:

δequivalent >20%

Φresisted =25%g

For Achaia – Ilia EQ, for:

δequivalent =20%

results:

Φeffective ≈ Φresisted =25%g

22/23

εresisted =12%g*1.7=21%g





•Conclusions

•Proposal

PROPOSALS:

Terms “Hysteretic Damping and “Behavior Factor” were first defined to

quantify the response of reinforced concrete elements and structures. The

values of these terms are strongly affected (among others) by the properties

of steel reinforcement.

For unreinforced masonry structures, is suggested the adoption of term

“Equivalent Damping” in order to describe their inelastic response, during

strong earthquakes, and its beneficial contribution to the absorption of the

imposed seismic energy.

“Equivalent Damping”, is suggested to represent the “Viscous Damping” and

the “Friction Damping” that results from local failures between:

a) the connection surfaces of “mortar – stone or brick”

b) and/or “mortar – mortar” failures

c) and/or “brick – brick” failure

through friction.

δequivalent = function (δviscous, δ“friction”)

“Palaia Mitropolis” - 11th century Christian Cathedral in the city of Veroia –

Main building and Minaret (later addition)

Structural Health Monitoring of civil engineering structures subjected to ambient excitations

Research Team: Lekidis Vasilios (Scientific Coordinator)

Karakostas Christos

Salonikios Thomas

Makarios Triantafyllos

Morfidis Konstantinos


Mode shapes of main building

“Palaia Mitropolis” - 11th century Christian Cathedral in the city of Veroia –Main building

Mode shapes of minaret


“Palaia Mitropolis” - 11th century Christian Cathedral in the city of Veroia –

Minaret (later addition)

“Utilization of EPPO Strong Motion Network Records for the Determination of

Rational Seismic Loads for Masonry Monuments ”

Thomas N. Salonikios

Senior Researcher, EPPO

Thank you for your Attention

Workshop:

“Seismic Protection of Monuments ”

Workshop: Seismic Protection of Monumentsecpfe.oasp.gr/sites/default/files/files/Thomas N_...

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