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

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

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

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)

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

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

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

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)

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

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

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

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

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)

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)

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”)

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 5...50 additional reinf.: 18  5...50 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

Suggested repair of fire damaged structural elements 70 570 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

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