4EWICS

TYPOLOGICAL ANALYSIS OF

EARLY REINFORCED CONCRETE

HOUSING BUILDINGS IN

ROMANIA

MARIA BOSTENARU

IUSS - ROSE, Pavia

ITALY

Overview

Introduction

Features

Problems and opportunities

Diagnosis and mission

Outlook to the European context

Conclusions

Introduction

Features:

typical view, load bearing elements

Features: architectural plan

Features: structural details

Features: seismic defficiencies


Seismic vulnerability

Seismic hazard

Very Poor Seismic Performance

A (High)

B

Medium

C

D

E

Excellent Seismic Performance

F (Low)

< O >

Year Earthquake Epicenter Richter magnitude Maximum Intensity

1940 Vrancea 7.4 7

1977 Vrancea 7.2 8

1986 Vrancea 7 8

1990 Vrancea 6.7 7


Building site Vulnerable building

Problems and opportunities:

building materials

Structural

element

Building

materials

Characteristic strength Mix Proportion/

Dimensions

Comments

Infill walls clay brick

compression strength between

2.6MPa (min for mark C50) and

10.0MPa (average for mark C100),

bending strength between 1.5MPa

(min for mark C50) and 2.1MPa

(average for mark C100)

7cm (63mm) x

14cm (115mm) x

28cm (240mm)

[brick itself (brick

with mortar)]

Façade walls: 28/34cm thick,

Partition walls 10/16cm.

The mark of brick and mortar

is unknown; the strength of

solid bricks was determined

experimentally by Lungu.

Columns

Reinforced

concrete

(RC)

7-15MPa (mean 12)

round smooth steel reinforcement

[Bălan]

‘ F i e n i ’ [ 6 ] c e m e n t 2 4 0 - 270kg/m³

w i t h a g g r e g a t e s 0 - 3 m m ( [ P r a g e r ] ,

p . 3 9 4 , 1 9 4 - 1 9 9 ) , m i x p r o p o r t i o n

o f 1 , 5 m ³ g r a v e l / m ³ 1 : 3 m o r t a r

( 7 0 0 k g c e m e n t + 1 m ³ s a n d )

1 0 0 - 1 2 0 k g s t e e l / m ³

c o n c r e t e . R e - b a r s :

s p a c i n g 2 5 - 3 0 c m ,

d i s t r i b u t e d

g e o m e t r i c a l l y .

S t i r r u p s : d i a m e t r e 6 -

8 m m , s p a c i n g 2 5 -

3 5 c m .

R e i n f o r c e m e n t o f t e n l e s s

t h a n 0 , 5 % . I n s u f f i c i e n t l a p

s p l i c i n g a n d s t i r r u p s . S t i r r u p s

o n l y c o n n e c t t h e c o r n e r R e -

b a r s , s p a c e d u p t o 1 m i n

b a d l y e x e c u t e d c o n s t r u c t i o n s

[Bălan]. T h e ‘ F i e n i ’ c e m e n t

h a d 1 0 d a y s h a r d e n i n g t i m e .

W o o d s c a f f o l d i n g

Beams RC see above reinforcement

distribution - no data

Roof/

Floors RC see above


Structural

Element

Seismic Deficiency Earthquake

Resilient Features

Earthquake Damage Patterns

Wall additional loads for the structure,

especially in case of facade consoles

increasing frame

stiffness

out-of-plane (leading to further torsion) and rifts

(especially X).

Columns poor reinforcement (<0.6%, bars of

10mm diameter, sparse stirrups),

evtl. low cement quantity in concrete;

non-verticality,

poor section conformation (long

rectangles),

don’t form moment resisting frames with

beams.

- Soft storey: concrete spalling till destruction and

buckling of Re-bars at plastic hinges.

Mezzanine: brittle breaks with rifts at 45°. In the

oblique sections resulted the stirrups detached.

This sever damage can lead directly to collapse.

Current storey: damage along plastic hinges:

horizontal and oblique (brittle) X rifts, concrete

spalling, buckling of longitudinal reinforcement.

Beams Low cement quantity in concrete and

low reinforcement in speculatively built

blocks,

don’t form moment resisting frames with

columns (numerous secondary beams)

execution usually

careful

Long beams: rifts and concrete spalling on the

bottom in the plastic articulation (near the beam-

column-node).

Short beams: 0°-45° brittle but undangerous rifts

open the beam in whole height at plastic hinges.

Roof and

floors

Low cement quantity in concrete and

low reinforcement in speculatively built

blocks; simple slab floors are too elastic

sufficient stiffness

of embedded bricks

waffle system

In room slabs, balconies some rifts, at change of

stair flights some more rifts.

Diagnosis and mission:

relationship diagram among the features

Structural element Building materials

Structural element Seismic defficiencyEarthquake resilient

features

Earthquake

damage patterns

Seismic defficiency Seismic strengthening provision

Characteristic

strength

Mix proportion/

dimensions


analysis of a retrofit model projectStructural Deficiency Seismic strengthening provision

“Wilson”

high-rise: 2 basement levels, ground floor with

commercial spaces and 11 upper floors at the

corner tower

RC skeleton structure, with facade walls out of

brick masonry and interior walls from plates

irregular shape in plan, with inequal wings, a

sharp angle at the tower and an interior

courtyard

The building was heavily affected by the 1940 earthquake and

retrofitted afterwards with concrete walls between some columns

and jacketing of some columns.

Retrofit solution after 1977: rebuilding the collapsed corner

zone, set-back at all levels (fig.). The damaged reinforced

concrete members were repaired and strengthened through

concrete recasting or reinforced concrete jacketing on ground

floor, first floor and locally on the other floors, especially at the

‘brand walls’ to the north.


contemporary preventive retrofit (2003)

Outlook to the European context

Buildings of the Modernism in Vienna

Conclusions

France

Portugal

Greece

Austria

Spain

Italy

Potential for comparative studies of inner city housing

in areas of variate seismicity

architectural language

urban development policies

preservation requirements

THANK YOU!

4EWICS

Education

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