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STRENGTHENING STRUCTURES USING FRP COMPOSITE MATERIALS DAMIAN I. KACHLAKEV, Ph.D., P.E. California Polytechnic State University San Luis Obispo.

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Presentation on theme: "STRENGTHENING STRUCTURES USING FRP COMPOSITE MATERIALS DAMIAN I. KACHLAKEV, Ph.D., P.E. California Polytechnic State University San Luis Obispo."— Presentation transcript:

1 STRENGTHENING STRUCTURES USING FRP COMPOSITE MATERIALS DAMIAN I. KACHLAKEV, Ph.D., P.E. California Polytechnic State University San Luis Obispo

2 WHY COMPOSITES? ADVANTAGES OVER TRADITIONAL MATERIALS CORROSION RESISTANCE HIGH STRENGTH TO WEIGHT RATIO LOW MAINTENANCE EXTENDED SERVICE LIFE DESIGN FLEXIBILITY

3 COMPOSITES DEFINITION A combination of two or more materials (reinforcement, resin, filler, etc.), differing in form or composition on a macroscale. The constituents retain their identities, i.e.., they do not dissolve or merge into each other, although they act in concert. Normally, the components can be physically identified and exhibit an interface between each other.

4 DEFINITION Fiber Reinforced Polymer (FRP) Composites are defined as: A matrix of polymeric material that is reinforced by fibers or other reinforcing material

5 COMPOSITES MARKETS TRANSPORTATION CONSTRUCTION MARINE CORROSION-RESISTANT CONSUMER ELECTRICAL/ELECTRONIC APPLIANCES/BUSINESS AIRCRAFT/DEFENSE

6 U.S. COMPOSITES SHIPMENTS MARKET SHARE SEMI-ANNUAL STATISTICAL REPORT - AUGUST 26, 1996 Includes reinforced thermoset and thermoplastic resin composites, reinforcements and fillers. Includes reinforced thermoset and thermoplastic resin composites, reinforcements and fillers. SOURCE: SPI Composites Institute Transportation 30.6% Other- 3.4% Aircraft/Aerospace 0.7% Appliance/Business Equipment - 5.3% Construction 20% Consumer Products - 6% Marine % Electrical/ Electronic - 10% Corrosion-Resistant Equipment %

7 Infrastructure Benefits HIGH STRENGTH/WEIGHT RATIO ORIENTATED STRENGTH DESIGN FLEXIBILITY LIGHTWEIGHT CORROSION RESISTANCE LOW MAINTENANCE/LONG-TERM DURABILITY LARGE PART SIZE POSSIBLE TAILORED AESTHETIC APPEARANCE DIMENSIONAL STABILITY LOW THERMAL CONDUCTIVITY LOW INSTALLED COSTS

8 FRP COMPOSITE CONSTITUENTS RESINS (POLYMERS) REINFORCEMENTS FILLERS ADDITIVES

9 MATERIALS: RESINS PRIMARY FUNCTION: TO TRANSFER STRESS BETWEEN REINFORCING FIBERS AND TO PROTECT THEM FROM MECHANICAL AND ENVIRONMENTAL DAMAGE TYPES: –THERMOSET –THERMOPLASTIC

10 RESINS THERMOSET –POLYESTER –VINYL ESTER –EPOXY –PHENOLIC –POLYURETHANE

11 RESINS THERMOPLASTIC –ACETAL –ACRYRONITRILE BUTADIENE STYRENE (ABS) –NYLON –POLYETHYLENE (PE) –POLYPROPYLENE (PP) –POLYETHYLENE TEREPHTHALATE (PET)

12 RESINS THERMOSET ADVANTAGES –THERMAL STABILITY –CHEMICAL RESISTANCE –REDUCED CREEP AND STRESS RELAXATION –LOW VISCOSITY- EXCELLENT FOR FIBER ORIENTATION –COMMON MATERIAL WITH FABRICATORS

13 RESINS THERMOPLASTIC ADVANTAGES –ROOM TEMPERATURE MATERIAL STORAGE –RAPID, LOW COST FORMING –REFORMABLE –FORMING PRESSURES AND TEMPERATURES

14 POLYESTERS LOW COST EXTREME PROCESSING VERSATILITY LONG HISTORY OF PERFORMANCE MAJOR USES: –Transportation – Construction – Marine

15 VINYL ESTER SIMILAR TO POLYESTER EXCELLENT MECHANICAL & FATIGUE PROPERTIES EXCELLENT CHEMICAL RESISTANCE MAJOR USES: –Corrosion Applications - Pipes, Tanks, & Ducts

16 EPOXY EXCELLENT MECHANICAL PROPERTIES GOOD FATIGUE RESISTANCE LOW SHRINKAGE GOOD HEAT AND CHEMICAL RESISTANCE MAJOR USES: –FRP Strengthening Systems –FRP Rebars –FRP Stay-in-Place Forms

17 PHENOLICS EXCELLENT FIRE RETARDANCE LOW SMOKE & TOXICITY EMISSIONS HIGH STRENGTH AT HIGH TEMPERATURES MAJOR USES: –Mass Transit - Fire Resistance & High Temperature –Ducting

18 POLYURETHANE TOUGH GOOD IMPACT RESISTANCE GOOD SURFACE QUALITY MAJOR USES: –Bumper Beams, Automotive Panels

19 SUMMARY: POLYMERS WIDE VARIETY AVAILABLE SELECTION BASED ON: –PHYSICAL AND MECHANICAL PROPERTIES OF PRODUCT –FABRICATION PROCESS REQUIREMENTS

20 Physical Properties of Thermosetting Resins Used in Structural Composites

21 MATERIAL: FIBER REINFORCEMENTS PRIMARY FUNCTION: CARRY LOAD ALONG THE LENGTH OF THE FIBER, PROVIDES STRENGTH AND OR STIFFNESS IN ONE DIRECTION CAN BE ORIENTED TO PROVIDE PROPERTIES IN DIRECTIONS OF PRIMARY LOADS

22 REINFORCEMENTS NATURAL MAN-MADE MANY VARIETIES COMMERCIALLY AVAILABLE

23 MAN-MADE FIBERS ARAMID BORON CARBON/GRAPHITE GLASS NYLON POLYESTER POLYETHYLENE POLYPROPYLENE

24 FIBER PROPERTIES DENSITY (g/cm 3 )

25 FIBER PROPERTIES TENSILE STRENGTH x10 3 psi

26 FIBER PROPERTIES STRAIN TO FAILURE (%)

27 FIBER PROPERTIES TENSILE MODULUS 10 6 psi

28 FIBER PROPERTIES CTE - Longitudinal x10 -6 / 0 C

29 FIBER PROPERTIES THERMAL CONDUCTIVITY x10 -6 / 0 C BTU-in/hr-ft F

30 FIBER REINFORCEMENT GLASS (E-GLASS) –MOST COMMON FIBER USED –HIGH STRENGTH –GOOD WATER RESISTANCE –GOOD ELECTRIC INSULATING PROPERTIES –LOW STIFFNESS

31 GLASS TYPES E-GLASS S-GLASS C-GLASS ECR-GLASS AR-GLASS

32 FIBER REINFORCEMENT ARAMID (KEVLAR) –SUPERIOR RESISTANCE TO DAMAGE (ENERGY ABSORBER) –GOOD IN TENSION APPLICATIONS (CABLES, TENDONS) –MODERATE STIFFNESS –MORE EXPENSIVE THAN GLASS

33 FIBER REINFORCEMENT CARBON –GOOD MODULUS AT HIGH TEMPERATURES –EXCELLENT STIFFNESS –MORE EXPENSIVE THAN GLASS –BRITTLE –LOW ELECTRIC INSULATING PROPERTIES

34 TYPICAL PROPERTIES OF STRUCTURAL FIBERS

35 ADVANTAGES AND DISADVANTAGES OF REINFORCING FIBERS

36 FIBER ORIENTATION ANISOTROPIC UNIDIRECTIONAL BIAS - TAILORED DIRECTION –0 O - flexural strengthening –90 O - column wraps –+ /- 45 O - shear strengthening ANGLE VARIES BY APPLICATION

37 DEGREE OF ANISOTROPY OF FRP COMPOSITES

38 PROPERTIES OF UNIDIRECTIONAL COMPOSITES

39 ELASTIC AND SHEAR MODULI OF FRP COMPOSITES

40 REINFORCEMENTS SUMMARY TAILORING MECHANICAL PROPERTIES –TYPE OF FIBER –PERCENTAGE OF FIBER –ORIENTATION OF FIBER

41 COMPARISON OF AXIAL AND FLEXURAL EFFICIENCY OF FRP SYSTEMS

42 DESIGN VARIABLES FOR COMPOSITES TYPE OF FIBER PERCENTAGE OF FIBER or FIBER VOLUME ORIENTATION OF FIBER –0 o, 90 o, +45 o, -45 o TYPE OF POLYMER (RESIN) COST VOLUME OF PRODUCT - MANUFACTURING METHOD

43 DESIGN VARIABLES FOR COMPOSITES PHYSICAL: –tensile strength –compression strength –stiffness –weight, etc. ENVIRONMENTAL: –Fire –UV –Corrosion Resistance

44 TAILORING COMPOSITE PROPERTIES MAJOR FEATURE PLACE MATERIALS WHERE NEEDED - ORIENTED STRENGTH –LONGITUDINAL –TRANSVERSE –or between STRENGTH STIFFNESS FIRE RETARDANCY

45 STRUCTURAL DESIGN APPROACH FOR COMPOSITES

46 SPECIFIC MODULUS AND STRENGTH OF FRP COMPOSITE

47 FLOW CHART FOR DESIGN OF FRP COMPOSITES

48 MANUFACTURING PROCESSES Hand Lay-up/Spray-up Resin Transfer Molding (RTM) Compression Molding Injection Molding Reinforced Reaction Injection Molding (RRIM) Pultrusion Filament Winding Vacuum Assisted RTM (Va-RTM) Centrifugal Casting

49 PROCESS CHARACTERISTICS Hand Lay-up/Spray-up MAX SIZE:Unlimited PART GEOMETRY:Simple - Complex PRODUCTION VOLUME:Low - Med CYCLE TIME:Slow SURFACE FINISH:Good - Excellent TOOLING COST:Low EQUIPMENT COST:Low

50 PRODUCT CHARACTERISTICS Pultrusion CONSTANT CROSS SECTION CONTINUOUS LENGTH HIGH ORIENTED STRENGTHS COMPLEX PROFILES POSSIBLE HYBRID REINFORCEMENTS

51 MATERIAL PROPERTIES PROPERTIES OF FRP COMPOSITES VARY DEPENDING ON: –TYPE OF FIBER & RESIN SELECTED –FIBER CONTENT –FIBER ORIENTATION –MANUFACTURING PROCESS

52 REPAIR HYBRIDS (SUPER COMPOSITES): TRADITIONAL MATERIALS ARE JOINED WITH FRP COMPOSITES –WOOD –STEEL –CONCRETE –ALUMINUM

53 BENEFITS - SUMMARY LIGHT WEIGHT HIGH STRENGTH to WEIGHT RATIO COMPLEX PART GEOMETRY COMPOUND SURFACE SHAPE PARTS CONSOLIDATION DESIGN FLEXIBILITY LOW SPECIFIC GRAVITY LOW THERMAL CONDUCTIVITY HIGH DIELECTRIC STRENGTH

54 LIFE CYCLE ECONOMICS PLANNING/DESIGN/DEVELOPMENT COST PURCHASE COST INSTALLATION COST MAINTENANCE COST LOSS/WEAR COST LIABILITY/INSURANCE COSTS DOWNTIME/LOST BUSINESS COST REPLACEMENT/DISPOSAL/RECYCLING COST

55 LIFE CYCLE ECONOMICS (Examples) IBACH BRIDGE (SWITZERLAND) –CFRP LAMINATES- 50 TIMES MORE EXPENSIVE THAN STEEL PER KILOGRAM –CFRP LAMINATES- 9 TIMES MORE EXPENSIVE THAN STEEL BY VOLUME –REPAIR WORK REQUIREMENTS-175 KG STEEL OR 6.2 KG CFRP –MATERIAL COST-20 % OF THE TOTAL PROJECT COST

56 LIFE CYCLE ECONOMICS (Examples) HORSETAIL CREEK BRIDGE (OREGON) –CONVENTIONAL REPAIR (SHEAR ONLY-ONE BEAM)-$69,000 –FRP REPAIR (GFRP SHEAR ONLY-ONE BEAM)- $1850 –FRP REPAIR [SHEAR (GFRP)+ FLEXURE(CFRP), ONE BEAM]- $9850

57 CONCLUSIONS ECONOMICS ARE MORE THAN THE BASIC ELEMENTS OF MATERIALS, LABOR, EQUIPMENT, OVERHEAD, ETC. ENTIRE LIFE CYCLE ECONOMICS MUST BE CONSIDERED AND COMPARED TO THAT OF TRADITIONAL MATERIALS TO DETERMINE THE BENEFITS OF COMPOSITES IN A GIVEN APPLICATION

58 STRUCTURAL DESIGN WITH FRP COMPOSITES

59 EXTERNAL REINFORCEMENT OF RC BEAMS USING FRP BACKGROUND DESIGN MODELS –LACK OF DUCTILITY –FLEXURAL STRENGTHENING –SHEAR STRENGTHENING –PRESTRESSED FRP APPLICATION DESIGN METHODOLOGY AND ANALYSIS OTHER ISSUES –FATIGUE, CREEP, LOW TEMPERATURE FRP PERFORMANCE DESIGN EXAMPLES

60 FRP STRENGTHENED BEAMS BACKGROUND FRP VS. EXTERNALLY STEEL BONDED PLATES –CORROSION AT THE EPOXY-STEEL INTERFACE –STEEL PLATES DO NOT INCREASE STRENGTH, JUST STIFFNESS –HIGH TEMPERATURES PERFORMANCE DIFFICULTIES DUE TO HEAVY WEIGHT OF THE STEEL PLATES –STRENGTHENING DESIGN BASED ON MATERIAL WEIGHT, NOT STRUCTURAL NEEDS –CONSTRUCTION DIFFICULTIES –TIME CONSUMING, HEAVY EQUIPMENT NEEDED

61 FRP STRENGTHENED BEAMS LACK OF DUCTILITY LINEAR STRESS-STRAIN PROFILE DEFINITION OF DUCTILITY –DEFLECTION AT ULTIMATE/DEFLECTION AT YIELD- NOT APPLICABLE FOR FRP MATERIAL –STRAIN-ENERGY ABSORPTION, I.E., AREA UNDER LOAD-DEFLECTION CURVE- OK FOR FRP COMPOSITES –IN GENERAL- THE HIGHER THE FRP FRACTION AREA, THE LOWER THE ENERGY ABSORPTION OF THE STRENGTHENED CONCRETE BEAM

62 FRP STRENGTHENED BEAMS

63 TYPICAL LOAD-DEFLECTION CURVE

64 FRP REINFORCED BEAMS- FAILURE MODES

65 FRP REINFORCEMENT OF RC COLUMNS Advantages of Strengthening Columns with FRP Jackets –Increased Ductility –Increased Strength –Low Dead Weight –Reduced Construction Time –Low Maintenance

66 FRP REINFORCEMENT OF RC COLUMNS Factors Influencing the Behavior of FRP- Retrofitted Columns –Column composition –Column geometry –Current condition –Type of loading –Environmental conditions

67 DESIGN OF FRP RETROFIT OF RC COLUMNS Shear Strengthening Flexural Hinge Confinement Lap Splice Clamping

68 LOAD-DISPLACEMENT CURVE (Before Strengthening)

69 LOAD-DISPLACEMENT CURVE (After Strengthening)

70 COLUMN DUCTILITY

71 FRP REINFORCEMENT OF RC COLUMNS Advantages of Strengthening Columns with FRP Jackets –Increased Ductility –Increased Strength –Low Dead Weight –Reduced Construction Time –Low Maintenance

72 FRP REINFORCEMENT OF RC COLUMNS Factors Influencing the Behavior of FRP- Retrofitted Columns –Column composition –Column geometry –Current condition –Type of loading –Environmental conditions

73 LOAD-DISPLACEMENT CURVE (Before Strengthening)

74 LOAD-DISPLACEMENT CURVE (After Strengthening)

75 COLUMN DUCTILITY

76 CONSTRUCTION PROCESS Preparation of the Concrete Surface Mixing Epoxy, Putty, etc. Preparation of the FRP Composite System Application of the FRP Strengthening System Anchorage (if recommended) Curing the FRP Material Application of Finish System

77 CONCRETE SURFACE PREPARATION Repair of the existing concrete in accordance to: –ACI 546R-96 Concrete Repair Guide –ICRI Guideline No Guide for Surface Preparation for the Repair of Deteriorated Concrete... Bond Between Concrete and FRP Materials –Should satisfy ICRI Guide for Selecting and Specifying Materials for Repair of Concrete Surfaces

78 CONCRETE SURFACE PREPARATION Repair Cracks inches or Wider –Epoxy pressure injected –To satisfy Section 3.2 of the ACI 224.1R-93 Causes, Evaluation and Repair of Cracks… Concrete Surface Unevenness to be Less than 1 mm Concrete Corners- Minimum Radius of 30 mm

79 APPLICATION OF THE FRP COMPOSITE In Accordance to Manufacturers and Designer's Specifications –Priming –Putty Application –Under-coating with Epoxy Resin –Application of the FRP Laminate/ FRP Fiber Sheet –Over-coating with Epoxy Resin

80 CURING OF THE FRP COMPOSITES In Accordance to Manufacturers Specifications –Temperature ranges and Curing Time- varies from few hours to 15 days for different FRP systems Cured FRP Composite –Uniform thickness and density –Lack of porosity

81 CONSTRUCTION PROCESS Typical RC Beam in Need for Repair –corroded steel –spalling concrete

82 CONSTRUCTION PROCESS Deteriorated Column / Beam Connection

83 CONSTRUCTION PROCESS Concrete Surface Preparation –Smooth, free of dust and foreign objects, oil, etc. –Application of primer and putty (if required by the manufacturer)

84 CONSTRUCTION PROCESS Preparation of the FRP Composites for Application –Follow manufacturers recommendations

85 CONSTRUCTION PROCESS Priming of the Concrete Surface Application of the Undercoating epoxy Layer (adhesive when FRP pultruded laminates are used)

86 CONSTRUCTION PROCESS Application of CFRP Fiber Sheet on a Beam- Wet Lay-Up Process Similar for Application of Pultruded Laminates

87 CONSTRUCTION PROCESS Column Wrapping with Automated FRP Application device

88 CONSTRUCTION PROCESS Robo Wrapper by Xxsys Technologies

89 CONSTRUCTION PROCESS Column Wrapping Device


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