REPAIR AND STRENGTHENING OF REINFORCED CONCRETE COLUMNS AND BEAMS ICRI – International Concrete Repair Institute Transportation Structures 2010 Fall Convention Pittsburgh October 20-22

2/83 ICRI 2010 – Pittsburgh October UHPFRCC Ultra High Performance Fiber Reinforced Cementitious Composites

3/83 ICRI 2010 – Pittsburgh October UHPFRCC

4/83 ICRI 2010 – Pittsburgh October Jacketing

5/83 ICRI 2010 – Pittsburgh October Tensile tests according Italian Standard L = 330 mm t = 13 mm b p = 30 mm t bpbp L Characterization in tension – stress deformation

6/83 ICRI 2010 – Pittsburgh October Adhesion tests

7/83 ICRI 2010 – Pittsburgh October Adhesion tests GF5 Ordinary concrete

8/83 ICRI 2010 – Pittsburgh October Preparation of the support

9/83 ICRI 2010 – Pittsburgh October Strengthening of columns

10/83 ICRI 2010 – Pittsburgh October Existing column f c =15MPa

11/83 ICRI 2010 – Pittsburgh October Existing column

12/83 ICRI 2010 – Pittsburgh October Strengthened column UHPFRC f c =170MPa f ct =11MPa

13/83 ICRI 2010 – Pittsburgh October Stress distributions

14/83 ICRI 2010 – Pittsburgh October Strengthened column

15/83 ICRI 2010 – Pittsburgh October Traditional jacketing f c =30MPa

16/83 ICRI 2010 – Pittsburgh October Strengthening with FRP

17/83 ICRI 2010 – Pittsburgh October Comparison

18/83 ICRI 2010 – Pittsburgh October Seismic retrofitting

19/83 ICRI 2010 – Pittsburgh October School building in Zagarolo

20/83 ICRI 2010 – Pittsburgh October In situ tests f c =11MPa

21/83 ICRI 2010 – Pittsburgh October Strengthening with GF5 UHPFRCC UHPFRCC 130MPa 40 mm

22/83 ICRI 2010 – Pittsburgh October Column tests

23/83 ICRI 2010 – Pittsburgh October Load history

24/83 ICRI 2010 – Pittsburgh October Results

25/83 ICRI 2010 – Pittsburgh October Results

26/83 ICRI 2010 – Pittsburgh October Numerical prediction

27/83 ICRI 2010 – Pittsburgh October Joint tests

28/83 ICRI 2010 – Pittsburgh October Load history

29/83 ICRI 2010 – Pittsburgh October 20-22

30/83 ICRI 2010 – Pittsburgh October 20-22

31/83 ICRI 2010 – Pittsburgh October 20-22

32/83 ICRI 2010 – Pittsburgh October 20-22

33/83 ICRI 2010 – Pittsburgh October 20-22

34/83 ICRI 2010 – Pittsburgh October Jobsite application

35/83 ICRI 2010 – Pittsburgh October Jobsite application

36/83 ICRI 2010 – Pittsburgh October Jobsite application

37/83 ICRI 2010 – Pittsburgh October Jobsite application

38/83 ICRI 2010 – Pittsburgh October Beam strengthening

39/83 ICRI 2010 – Pittsburgh October HPFRCC cm Jacketing

40/83 ICRI 2010 – Pittsburgh October BEAMS: ASR, BCR, ACR (300x500x4550 mm) ASR: RC beam with 2 rebars having a 16mm diameter    0.3%) BCR: concrete beam without rebars + jacketing in HPFRCC ACR: RC beam (   0.3%) + jacketing in HPFRCC Experimental program

41/83 ICRI 2010 – Pittsburgh October Results

42/83 ICRI 2010 – Pittsburgh October Results

43/83 ICRI 2010 – Pittsburgh October Sandblasting of the beams Jobsite application

44/83 ICRI 2010 – Pittsburgh October Waterjetting The pouring Jobsite application

45/83 ICRI 2010 – Pittsburgh October Thixotropic UHPFRCC application Jobsite application

46/83 ICRI 2010 – Pittsburgh October Protection of material with a thermal jacket Jobsite application

47/83 ICRI 2010 – Pittsburgh October First example of application: PROJECT OF SEISMIC ADJUSTMENT OF THE “HOSPITAL COTUGNO” OF BARI Object : Hospital Cotugno Place : Bari Repair : Seismic rehabilitation Reinforcement of beam and pot floor with a cooperating cover layer Quantity : 22’000 m2 (15 mm) Material : Micro-concrete fiber-reinforced HPFRCC The other Jobsite applications

48/83 ICRI 2010 – Pittsburgh October PROBLEM NECESSITY OF SEISMIC RETROFITTING OF THE STRUCTURE The project foresees the realisation of RC shear walls destinated to resist the horizontal seismic actions PROBLEM: TRASFER OF THE STRESSES OF THE FLOOR TO THE SHEAR WALLS; THE EXISTING FLOOR, WITH A STRUCTURALLY COOPERATING TOP DECK OF 2 cm, WAS NOT ABLE TO FULLFILL THIS FUNCTION The other Jobsite applications

49/83 ICRI 2010 – Pittsburgh October SOLUTION TO OBTAIN THE DIAPHRAGM EFFECT HAS BEEN INSTALLED ON THE TOPPING OF THE FLOOR A STRUCTURAL COOPERATIVE DECK WITH LOW THIKCNESS (15 mm) IN FIBRE-REINFORCED CONCRETE WITH VERY HIGH MECHANICAL PERFORMANCE, FORMULATED AD-HOC BASED ON THE STRUCTURAL REQUIREMENTS The other Jobsite applications

50/83 ICRI 2010 – Pittsburgh October APPLICATION 1.VERIFICATION OF THE ADHESION TO SUBSTRATE APPLICATION OF SAMPLE IN JOBSITE TO VERIFY THE ADHESION OF THE PRODUCT TO THE SUBSTRATE IN THAT SITUATION: CONNECTORS WITH STUBS IN REFOR-tec® GF5/ST HS, OBTAINED THROUGH SIMPLE DRILLING METAL CONNECTORS (DRILLING + FISCHER) NO CONNECTORS- ONLY SANDBLASTING AND WATERJETTING NO CONNECTORS – ONLY WATERGETTING The other Jobsite applications

51/83 ICRI 2010 – Pittsburgh October THE CURING PERIOD COMPLETED, MEASUREMENTS DEMONSTRATE THE ADHESION TO THE SUBSTRATE : OPTIMAL ADHESION OF THE REINFORCING COVERLAYER REFOR-tec ® GF5/ST HS EVEN WITHOUT CONNECTOR SYSTEM, ONLY AFTER ADEQUATE SURFACE PREPARATION The other Jobsite applications

52/83 ICRI 2010 – Pittsburgh October The other Jobsite applications APPLICATION OF THE MATERIAL

53/83 ICRI 2010 – Pittsburgh October The other Jobsite applications LIGHT TAMPERING IMMEDIATE APPLICATION OF CURING COMPOUND UR 20

54/83 ICRI 2010 – Pittsburgh October The other Jobsite applications DETAIL OF THE APPLICATION – RETAKING OF THE FLOORS

55/83 ICRI 2010 – Pittsburgh October TESTING-CONTROLLING THE ADHESION TO THE SUBSTRATE The other Jobsite applications

56/83 ICRI 2010 – Pittsburgh October RESULT THE APPLICATION OF SEVERAL THOUSEND SQUARE METERS WITHOUT CUTTING JOINTS AND WITHOUT ANY CRACKING. PERFECT ADHESION OF THE MATERIAL TO THE SUBSTRATE The other Jobsite applications

57/83 ICRI 2010 – Pittsburgh October ADVANTAGES IN RESPECT WITH A TRADITIONAL CONCRETE COOPERATIVE DECK 1.Low application thickness (15-20 mm ) 2.Adhesion the substrate without necessity for connectors or resins 3.No reinforcement nets 4.Very high ductility and resistance to cyclic load 5.Increase of the bearing capacity in terms of bending moment and stiffness and a reduction of the deflection of the floor 6.Speed of application thanks to self-levelling material properties Limited increase of load The other Jobsite applications

58/83 ICRI 2010 – Pittsburgh October Repair after fire

59/83 ICRI 2010 – Pittsburgh October Beams residual properties 4 Ø 16mm 300mm 500mm Steel Felicetti & Meda (2005) Concrete Eurocode 2

60/83 ICRI 2010 – Pittsburgh October Thermal analysis ISO 834

61/83 ICRI 2010 – Pittsburgh October Analytical model Coccia & Rinaldi 2006 steelconcrete

62/83 ICRI 2010 – Pittsburgh October Beams residual properties

63/83 ICRI 2010 – Pittsburgh October Beams repair HPFRC

64/83 ICRI 2010 – Pittsburgh October HPFRC EC2 Mindeguia et al. (2007) HPFRC 950°C De Chefdebien et al. (2007) HPFRC thermal properties

65/83 ICRI 2010 – Pittsburgh October Fire resistance of the repaired beam

66/83 ICRI 2010 – Pittsburgh October Fire resistance of the repaired beam

67/83 ICRI 2010 – Pittsburgh October Column residual properties

68/83 ICRI 2010 – Pittsburgh October Column repair

69/83 ICRI 2010 – Pittsburgh October Initial damage 90′ - new fire 90′

70/83 ICRI 2010 – Pittsburgh October Initial damage 180′ - new fire 180′

71/83 ICRI 2010 – Pittsburgh October Seismic retrofitting of shear walls

72/83 ICRI 2010 – Pittsburgh October Reference model: stair block element of an existing three storey building Experimental model: 1:3 scaled R/C wall Experimental test

73/83 ICRI 2010 – Pittsburgh October t =15mm Proportioned to resist vertical loads only Proportioned to resist seismic loads aggregate dmax=15mm F5/70mm longit. rebars F4/100mm stirrups Experimental test

74/83 ICRI 2010 – Pittsburgh October High strength, waved steel mesh made of bent wires Tensile test on steel mesh single wire High performance steel mesh

75/83 ICRI 2010 – Pittsburgh October bare high strength steel mesh High performance jacket

76/83 ICRI 2010 – Pittsburgh October I phase: R/C wall sandblast Wall sandblast

77/83 ICRI 2010 – Pittsburgh October I phase: R/C wall sandblast II phase: Positioning of the steel mesh Application of the steel mesh

78/83 ICRI 2010 – Pittsburgh October I phase: R/C wall sandblast II phase: Positioning of the steel mesh III phase: 15 mm HPC jacket casting Jacket casting

79/83 ICRI 2010 – Pittsburgh October drift 3.6%  u /  y = 9  y = 12mm;  u = 109mm) Results

80/83 ICRI 2010 – Pittsburgh October Deformed shear wall at collapse drift = 3.5% 1.5b 12/16 Results

81/83 ICRI 2010 – Pittsburgh October FE analysis

82/83 ICRI 2010 – Pittsburgh October FE analysis: results

83/83 ICRI 2010 – Pittsburgh October Conclusions - The proposed technique allow a significant increase of the bearing capacity in terms of bending moment, axial force and stifness of pillars and beams - A simple sandblasting has ensured the perfect bond between the base concrete material and the strengthening UHPFRCC layer; - The strengthening has provided a remarkable increase of stiffness of beams and floors; as a consequence, the midspan displacement at serviceability limit state has been reduced of about 12 times; This behaviour is comparable to the application of a prestressing load; - The small thickness of the jacket does not change significantly the elements geometry - Increase of thermal and static resistance of structural elements after the fire -The jacket enhance the durability of the structure