1. EXAMINATION, ASSESSMENT AND REPAIR
COST Action TU 0904
“St. CIRIL and METHODIUS” UNIVERSITY
FACULTY OF CIVIL ENGINEERING
SKOPJE - MACEDONIA
Cvetkovska Meri
Lazarov Ljupco
Todorov Koce
EXAMINATION, ASSESSMENT AND REPAIR
OF RC STRUCTURE OF BUILDING DAMAGED IN FIRE

2. Characteristic damages of RC elements recorded in situ
COST Action TU 0904
Characteristic damages of RC elements recorded in situ
Change of concrete color.
Red color indicate temperaures round 6000C
Flexy color indicate temperaures round 9000C

3. Characteristic damages of RC elements recorded in situ
COST Action TU 0904
Characteristic damages of RC elements recorded in situ
Cracks along main reinforcement
Cracks in direction
of stirrups
Crushing of concrete and falling off of concrete parts along the edges of linear elements up to the reinforcement

4. Characteristic damages of RC elements recorded in situ
COST Action TU 0904
Characteristic damages of RC elements recorded in situ
Change of color and structure of concrete (fissures and cracks inside the concrete mass)

5. Experimental determination of the residual concrete strength
COST Action TU 0904
Experimental determination of the residual concrete strength A B8 V7 G7 D7 R2 T2
SII MS E7 S4 S1 S2 S3 P1 R4 R1 R3
Position of the test specimens, taken from
RC walls and RC slabs on 7th and 8th floor

6. Experimental determination of the residual concrete strength
COST Action TU 0904
Experimental determination of the residual concrete strength
Before testing all the specimens were divided in two slices. The deteriorated (burned) slices had small height (3-6cm) and rough surface
They were specially prepared by adding plaster layers, so the measured values for the compressive concrete strength were reduced with coefficients depending on the shape and height (h) of the deteriorated concrete specimens

7. Concrete strength testing results
COST Action TU 0904
Concrete strength testing results

8. Thermal and structural response of four-bay,
COST Action TU 0904
Thermal and structural response of four-bay,
five-story RC frame
1.2
1.7
1.8
5.8
4.2
4.22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 87 88 89 90 91 92 93 94 95 96 97 98 99
100 73 74 75 76 77 78 79 80 81 82 83 84 85 86 59 60 61 62 63 64 65 66 67 68 69 70 71 72 45 46 47 48 49 50 51 52 53 54 55 56 57 58 31 32 33 34 35 36 37 38 39 40 41 42 43 44
N=3500KN
216
516
316
122+616
616
P.800
P.900
P.700
P.600
1418
8/15/15cm
Schematic presentation of fired frame R2
(elements discretization and details of reinforcing)

9. Thermal and structural response of column S4
COST Action TU 0904
Thermal and structural response of column S4 a) b)
a) temperature distribution b) residual concrete strength
in the cross section of the most damaged column

10. Thermal and structural response of column S4
COST Action TU 0904
Thermal and structural response of column S4 1 3 10
16 a) b)
a) stress distribution b) stress distribution
at max. temperatures after the cooling period

11. Thermal and structural response of the beam
COST Action TU 0904
Thermal and structural response of the beam
RC slab
0.30 m
0.30 m a) b)
a) temperature distribution b) residual concrete strength
in the cross section of the most damaged beam

12. Thermal and structural response of four-bay,
five-story RC frame 1 3 10
16
-100
-75
-50
-25 25 50 75
100
-10 -6 -2 e
*1000 s in % of f y
(T)
arm.3
arm.10
Time redistribution of stresses in reinforcement
in the cross section of the most damaged column

13. Interaction diagrams for column S4
COST Action TU 0904
Interaction diagrams for column S4
M-N diagram for column S4 (before action of fire
and at the moment of max. temperature)

14. Interaction diagrams for column S4
COST Action TU 0904
Interaction diagrams for column S4
M-N diagram for column S4 (before action of fire, at the moment of max. temperature, after cooling phase and after replacement of 5cm thick layer of burned concrete)

15. Interaction diagrams for column S4
COST Action TU 0904
Interaction diagrams for column S4
M-N diagram for column S4 (before action of fire, at the moment of max. temperature, after cooling phase
and after suggested repair with “jacketing”)

16. Suggested repair of fire damaged structural elements
COST Action TU 904
Suggested repair of fire damaged structural elements
RC wall
addit. reinf.: 18
RA 400/500
stirrup:
10/7,5/15cm
GA 240/360
d6cm
d=5-6cm
new concrete layer МВ 35
66 cm
33 cm
30 cm
additional reinf.: 218 2
additional reinf.: 18 
welded to the existing stirrup
66 cm
45 cm
15 cm
d3cm
new concrete layer МВ 35
additional reinf.: 220
RA 400/500
5 cm
60 cm
d6cm
lean concrete layer
thermal isolation
“OMNIA”
slab
add. stirrup
10/10/20cm
GA 240/360
Repair details of column S4 and beams from frame R2

17. Suggested repair of fire damaged structural elements70
570 60
190
695
2 120 L=7.25m , n=12 S1 S2 15
existing reinforcement
additional stirrups n=362
(welded to the existing stirrups)
RC wall, d=25cm
concrete cover to be eliminated
up to the existing stirrups
add. reinforcement 20
(at the inside)
Detail of additional reinforcing with 20 (RA 400/500-2) along the beam of the frame R1 60
520
RC wall P1, d=30cm
7 116 L=5.7m , n=12 S2
RC wall S3
existing reinforcement
Detail “B” 30
375
570
5 216
8 116
RC wall, d=25cm
opening through the RC wall
(for the add. reinforcement)
8 116 L=2.65m , n=12
260
Detail “С”
7 116
5 216 L=3.20m , n=22
315
concrete cover to be eliminated
up to the existing stirrups
Detail of additional reinforcing with 16 (RA 400/500-2) along the beam of the frame R2

18. Thank you for the atTention
COST Action TU 0904
Thank you for the atTention