Impact of seismic

retrofit on interwar RC

housing

Maria BOSTENARU

Rui PINHO

ROSE School, Pavia, Italy

Overview

Introduction

Modelling of interwar housing buildings

Earthquake behaviour of interwar buildings

Retrofit, and discussion of the impact of such

measures

Optimisation of a retrofit measure

Conclusions

Modelling of interwar housing

buildings

The IVth CIAM in 1933 in Athens and

architectural characteristics of historic RC

housing buildings in earthquake prone parts

of Europe

Structural characteristics

Modern buildings in Greece

Bedroom / night zone

Living room, including dinning

Corridors / circulation zone

Bathrooms, toillets

Kitchen

Hall / vertical circulation

Deposit / external circulation

Legend:

Functional scheme in a Greek

apartment building

Modern buildings in Romania

Functional scheme in a

Romanian apartment building

Bedroom / night zone

Living room, including dinning

Corridors / circulation zone

Bathrooms, toillets

Kitchen

Hall / vertical circulation

Deposit / external circulation

Legend:

Architectural typology

Bedroom / night zone

Living room, including dinning

Corridors / circulation zone

Bathrooms, toillets

Kitchen

Hall / vertical circulation

Deposit / external circulation

Legend:

1.

2. 3.

Modern buildings in Portugal

Earthquake behaviour of

interwar buildings

Design of a model of an interwar building

Effects of earthquakes on the structure

Model building:

facade and section

Model building:

plan of the current floor

Model building: plans of GF,

basement and set-back floors

Material models for concrete

and steel

Slab modeling

Section models

Finite elements model of the

building

Pushover curves

pushover X

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 50 100 150 200 250 300 350 400

Displacement N6206 (mm)

Base s

hear

(kN

)

Base Shear X

Base Shear X negative

pushover Y

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 50 100 150 200 250 300 350 400

Displacement N6206 (mm)

Base s

hear

(kN

)

Base Shear Y

Base Shear Y negative

Retrofit, and discussion of the

impact of such measures

Design of the retrofit measure

Impact of the measure

Layout of retrofit elements

1st phase:

soft storey

2nd phase

3rd phase

Retrofit options

pushover X

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 50 100 150 200 250

Displacement N6206 (mm)

Base s

hear

(kN

)

Base Shear X

Base Shear X retrofit2

Base Shear X retrofit 3

pushover Y

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

-15 35 85 135 185 235 285 335

Displacement N6206

Base s

hear

(N)

Base Shear Y

Base Shear Y retrofit2

Base Shear Y retrofit3

Deformed shapes

Most damaged elements

yield and spall GF

most damaged upper floor columns

Vrancea earthquake 1986

yield 1st floor

yield, spall GF

yield, spall, crush GF

yield GF

most damaged transversal beams

Vrancea earthquake 1986

yield in GF

beams

yield, crush in

GF beams

yield, spall, crush in GF

beams

most damaged longitudinal beams

Vrancea earthquake 1986

crush, spall, yield

GF

spall GF

yield 1st floor

yield GF

spall 1st floor

most damaged upper floor columns

Vrancea earthquake 1977

most damaged GF columns (also break)

Vrancea earthquake 1977

yield in beams

over basement

spall in beams

over basement

yield in beams over

1st and 2nd floor

most damaged longitudinal beams

Vrancea earthquake 1977

.

yield GF

yield, spall GF

most damaged beams

Thessaloniki earthquake 1978

yield GF

yield, spall GF

most damaged longitudinal beams

Vrancea earthquake 1990

Optimisation of a retrofit

measure

Optimisation of impact parameters

Re-assessment of the impact

Pushover curves

X

0

0,05

0,1

0,15

0,2

0,25

0 20 40 60 80 100 120 140 160

displacement (mm)

accele

rati

on

(g

)

unretrofitted 94 retrofitted negative 0,192

Y

0

0,05

0,1

0,15

0,2

0,25

0 50 100 150 200

displacement (mm)

accele

rati

on

(g

)

unretrofitted retrofitted 103 negative 0.192

Decision

treeHistorical

Building

Element

Material

Vulnerability

Structure

performance

Retrofit

elements

Strategy

Architect Engineer

Inhabitant Investor

Execution

Acceptance

Occupancy

Management

Availability

Indicators

Residential value

Reversibility

Guidelines

Displacement, maximal

Tension

Facade

Interior space

Structure

Demolition

Size change

Looks change

Construction material change

Material

Earthquake

Shape score

Structure score

Forces

Displacement, remaining

Element replacement

New element

Non-structural > structural

System completion

Strengthening/Stiffening

Enhanced ductility

Reduced demand

Duration

Noise

Relocation

Participation

Ownership form

Safety

Own expenses

Other benefits

During measure

After measure

After earthquake

Total costs/New bldg. – 30%

Aggregate

Building site

Phases

Repeatability

Construction material versus

Technology versus

Funds

Relocation space

Reparation/New building

Retrofit/New building

Reparation saving/Retrofit

Compatibility with old

Conservation of old

Maintenance new

Sustainability

Partial demolition

Detail of the model building

Geo-composite yarn weaving

Conclusions

Thank you!

Questions?