This document analyzes early reinforced concrete housing buildings in Romania. It describes their typical features such as load bearing walls and structural details. It also discusses problems like seismic vulnerability due to poor reinforcement and materials. The document examines case studies of buildings damaged in earthquakes and retrofit approaches to improve seismic performance by adding reinforcement or jacketing structural elements. It concludes by suggesting potential for comparative studies of similar building stock in other European countries.

1. TYPOLOGICAL ANALYSIS OF
EARLY REINFORCED CONCRETE
HOUSING BUILDINGS IN
ROMANIA
MARIA BOSTENARU
IUSS - ROSE, Pavia
ITALY

2. Overview
 Introduction
 Features
 Problems and opportunities
 Diagnosis and mission
 Outlook to the European context
 Conclusions

3. Introduction

4. Features:
typical view, load bearing elements

5. Features: architectural plan

6. Features: structural details

7. Features: seismic defficiencies

8. Problems and opportunities
 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

9. Problems and opportunities
Building site Vulnerable building

10. 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

11. Problems and opportunities
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.

12. Diagnosis and mission:
relationship diagram among the features
Structural element Building materials
Structural element Seismic defficiency
Earthquake resilient
features
Earthquake
damage patterns
Seismic defficiency Seismic strengthening provision
Characteristic
strength
Mix proportion/
dimensions

13. Diagnosis and mission:
analysis of a retrofit model project
Structural 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.

14. Diagnosis and mission:
contemporary preventive retrofit (2003)

15. Outlook to the European context
Buildings of the Modernism in Vienna

16. 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

17. THANK YOU!