STRUCTURAL STRENGTHENING PRESENTED BY: SCOTT DISTEFANO SIKA CORPORATION, LYNDHURST, NJ AIA PROGRAM NUMBER: SIK302
Key Learning Objectives Determine why structures need to be strengthened Highlight materials that can be used for structural strengthening along with their advantages and disadvantages Design considerations, along with available industry guidelines, for successful use of materials
This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Sika Corporation is a Registered Provider with the American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-aia members is available upon request.
AIA/CES Program This AIA/CES program delivers 1 learning unit of credit (1.0 LU) This program qualifies for Health, Safety and Welfare (HSW) credit Please sign the form and add your AIA member number if you wish to obtain credit for this seminar Sika will forward this information to AIA so that you will receive credit for this presentation Non-AIA members may receive CEU s upon request
WHAT ARE COMPOSITES? Composites are a combination of two or more distinct materials Fiber reinforced polymers (FRP) Fibers (carbon or glass) Resins (epoxy matrix) Reinforced concrete Concrete (matrix) Steel (reinforcement)
WHY DO STRUCTURES NEED STRENGTHENING? Insufficient reinforcement Corrosion damage Change in use Structural damage Seismic upgrade 1950 s 2000 s
U.S. INFRASTRUCTURE American Society of Structural Engineers Report Card Overall grade of America s Infrastructure: D+ Over 600,000 bridges in U.S. 1 in 11 rated structurally deficient 4 in 10 bridges 50 years or older Total infrastructure needs: $4.59 TRILLION over 10 years 8
ADVANTAGES OF FRP REPAIRS Cost/scheduling benefits Get in, Get out, Stay out! - FHWA Mantra for accelerated construction Reduced maintenance costs Light weight materials puts less strain on infrastructure Non-corrosive materials are designed for long-term performance Less expensive repairs allow for more structures to be repaired with fixed budget 9
CONFINEMENT / SEISMIC Additional loads Earthquake Ductility
FLEXURAL STRENGTHENING 11
SHEAR STRENGTHENING 12
COMBINED STRENGTHENING - ANCHORAGE 13
EXTERNAL PLATE BONDING MATERIALS CFRP Strips Fabrics Brackets Steel Plates Jackets GFRP Fabrics
CFRP vs. GFRP Active loading Damp/wet conditions Stiffness driven Extreme alkaline conditions Passive/seismic loading Dry conditions Extreme acidic conditions Economical
Steel vs. Composites Low material cost High installed cost Corrosive Heavy Fabrication required High maintenance High material cost Low installed cost Non-corrosive Lightweight No fabrication required Low maintenance
TYPICAL APPLICATIONS Bridges Girder Strengthening Column Wrapping Pier Upgrades Deck Stiffening
TYPICAL APPLICATIONS Buildings Modifications Change in use Wall strengthening Seismic upgrades
TYPICAL APPLICATIONS Parking Structures Shear Strengthening Corbel Upgrades Corrosion Damage
LIMITED ACCESS
SURFACE PREP Concrete prepared by sandblasting Concrete smoothed out using grinders All defects repaired using epoxy mortar
SURFACE PREPARATION
CONCRETE SURFACE PREPARATION Acid Etched Grinding Light Shotblast Light Scarification Medium Shotblast Medium Scarification Heavy Abrasive Blast Scabbled Heavy Scarification I.C.R.I Guideline # 03732
Testing Substrate Minimum tensile strength = 200 psi Substrate failure
SUBSTRATE PATCHING 25
PRE-CURED CFRP PLATES AND RODS 26
CLEANING CFRP STRIPS 27
CUTTING STRIPS ON-SITE 28
MIXING EPOXY RESIN Pre-mix components Low speed drill Uniformly blended
APPLYING EPOXY ONTO CFRP 30
APPLYING EPOXY TO SUBSTRATE 31
STRIP INSTALLATION Set strip by hand Work from one end to the other Moderate pressure 32
ROLLING CFRP ONTO CONCRETE Moderate pressure Ensures intimate contact 33
CENTRAL PARK WEST CONDO New octagon shaped staircase cut into reinforced concrete slab Carbon fiber plates inserted into grooves cut into concrete on top and bottom of slab 34
FRP FABRICS Available in carbon or glass Conforms to all shapes & sizes Unidirectional or Bidirectional Effective on concrete and masonry Wet or Dry Lay Up or Pre Saturated
SATURATING THE FABRIC Fabric Resin
SATURATING THE FABRIC MANUALLY 37
SURFACE PREPARATION Corners rounded to ½ minimum Blast clean surface Open pores Remove laitance Smooth and level
FABRIC APPLICATION
REMOVING AIR VOIDS
PROTECTIVE COATINGS Before After
MASONRY CAPABILITIES 27 osy unidirectional glass fabric with epoxy resin. 4-point bend deflection test.
FRP VS. CONVENTIONAL UPGRADE Simply supported beam; 35% upgrade in live load Bonded Steel Plate 3/16 inch bolted plate 245 lb. dead load Placed by lift truck Member Enlargement 2 #8 rebar, 4 in. grout 2,500 lb. dead load Formed and cured FRP Sheet 1 layer resin bonded 6 lb. dead load Placed by hand
DESIGNING WITH FRP Provides secondary reinforcement Must comply with local building and fire codes 44
FRP DESIGN SOFTWARE 45
CODES AND STANDARDS ACI 440.2R-08 Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures ACI 562-13 Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings Developed for adaptation into International Existing Building Code Use of FRP allowed as long as consistent with ACI 440 ICC Evaluation Service Technical evaluation of building products for compliance to building codes such as IBC Products independently tested per Acceptance Criteria 46
ADDITIONAL FRP APPLICATIONS
FRP RODS NEAR SURFACE MOUNTED REINFORCEMENT
SHEAR STRENGTHENING ANCHORAGE DETAILS FRP Rod Add Photo.. Structural Group
CARBON ROPE ANCHORS Anchoring and glass fibre fabrics on concrete or masonry Connecting carbon or glass fibre fabrics through concrete or masonry structures Flexible near surface mounted strengthening (NSM)
CARBON ROPE ANCHORS
CARBON ROPE ANCHORS
WOODEN MEMBERS
GLULAM BEAMS
POST-TENSIONING WITH CFRP Optimal use of Carbon Fiber Plates Reduces tensile strain in existing steel reinforcement Increases live load capacity of member Non-corrosive material adhesive Post-tensioned CFRP plate anchor anchor
Live End Dead End
BLAST DESIGN Embassy work Combat terrorism Chemical & Industrial Plants Airports Baker Engineering
BLAST HARDENING Brittle response of unretrofitted column to blast load Ductile and nearly elastic response to same blast after wrapped with fiber reinforced polymer (FRP)
PRESATURATED SYSTEMS
BACKGROUND Structural Strengthening was typically done with retrofitted steel Cheap material but Labor intensive and added significant weight In the 1980 s FRP composites started to be used for strengthening concrete Light weight Easy to apply Material cost offset by ease of application Early-mid 1990 s, Sika rolls out CFRP & GFRP systems for SikaWrap 103C and SikaWrap 100G Great success Extremely messy Quality control in the field is difficult 2015, Presaturated Fabrics are introduced into the market 67
STRENGTHENING EVOLUTIONS STEEL Low material cost High installed cost Corrosive Heavy Fabrication required Difficult on site adjustments High maintenance COMPOSITES High material cost Low installed cost Non-corrosive Light weight No fabrication Easy field adjustments Low Maintenance Transition from steel to composite is near 100% 68
STRENGTHENING EVOLUTIONS COMPOSITES High material cost Low installed cost Needs resin Light weight Low maintenance No fabrication PRESAT. COMPOSITES Higher material cost Lower installed cost Resin included Light weight Low maintenance No fabrication Can PreSaturated composites be the new normal? 69
BACKGROUND PreSaturated FRP systems are not new Used in aerospace industry Previously required: Refrigerated/Frozen storage Short shelf life Autoclave post cure Custom, highly specialized equipment 70
THE NEXT GENERATION OF FRP! PreSaturated FRP is the next generation in strengthening technology! 71
CURRENT FIBER WRAP SYSTEM Order & Ship Resin Order & Ship Fabric Prepare concrete Bring Saturator on site Mix Epoxy Primer Prime Concrete Fabric is cut on site (if necessary) Set up saturator Fabric is then saturated (saturator or table/rollers) Piece by piece, saturated fabric transported and given to installers Applied to primed surface Left to cure Clean up saturator and site Dispose of Resin pails 72
CURRENT FIBER WRAP SYSTEM Order & Ship Resin Order & Ship Fabric Prepare concrete Bring Saturator on site Mix Epoxy Primer Prime Concrete Fabric is cut on site (if necessary) Set up saturator Fabric is then saturated (saturator or table/rollers) Piece by piece, saturated fabric transported and given to installers Applied to primed surface Left to cure Clean up saturator and site Dispose of Resin pails 73
CURRENT FIBER WRAP SYSTEM Prep Work 74
CURRENT FIBER WRAP SYSTEM Repair Imperfections 75
CURRENT FIBER WRAP SYSTEM Mix & Apply Epoxy Primer 76
CURRENT FIBER WRAP SYSTEM Cut fabric to size 77
CURRENT FIBER WRAP SYSTEM Saturate Fabric with Resin Table or Saturator 78
CURRENT FIBER WRAP SYSTEM 79
CURRENT FIBER WRAP SYSTEM 80
CURRENT FIBER WRAP SYSTEM 81
PRESATURATED SYSTEM Some initial Steps are the same... Order Fabric Prepare concrete Mix Primer Prime Concrete Now it changes... Cut open pouch Cut fabric if necessary Applied to primed surface Left to cure 82
PRESATURATED SYSTEM Prep Concrete 83
PRESATURATED SYSTEM Mix Epoxy Primer 84
PRESATURATED SYSTEM Prime Concrete 85
PRESATURATED SYSTEM Open foil pouches when ready to apply 86
PRESATURATED SYSTEM Cut wet fabric if necessary 87
PRESATURATED SYSTEM Lay Wrap 88
PRESATURATED SYSTEM Finito 89
WHERE TO USE In difficult or standard applications such as: Load Increases Increased live loads Increased traffic volumes on bridges Installation of heavy machinery in industrial buildings Vibrating structures Changes of building utilization Seismic Strengthening Column wrapping Masonry walls Damage to Structural Parts Aging of construction materials Vehicle impact Fire Blast resistance 90 Change in Structural System Removal of walls or columns Removal of slab sections for openings Design or Construction Defects Insufficient reinforcements Insufficient structural depth
WHERE TO USE In difficult or standard applications such as: Load Increases Increased live loads Increased traffic volumes on bridges Installation of heavy machinery in industrial buildings Vibrating structures Changes of building utilization Seismic Strengthening Column wrapping Masonry walls Damage to Structural Parts Aging of construction materials Vehicle impact Fire Blast resistance 91 Change in Structural System Removal of walls or columns Removal of slab sections for openings Design or Construction Defects Insufficient reinforcements Insufficient structural depth New Application Areas? Telephone Poles Under water Tidal Zones Low/High Temp
ADVANTAGES Quality in the field Known Resin to Fabric Ratio Within 5% Material Certs for engineers Strengths Modulus R:F Ratio ISO 9001 Plant Full Traceability Drop in replacement for current products Reduction in Labor Reduce 5-6 man crew by 2-3 men Application efficiency Increase work rate by 20-30% 4 day project down to 3 No need to move saturated fabric around Ease of delivery Single source Non hazardous Can be easily transported or air freighted 92
ADVANTAGES MANUFACTURING How manufactured materials are traced: All raw materials include lot # and quantity Sales order generated = work instruction in system Includes BoM and lot # of each raw material Work instructions are converted into 6 digit lot number 93
ADVANTAGES PACKAGING 94
ADVANTAGES PACKAGING 95
ADVANTAGES QUALITY CONTROL Quality tests performed during processing of fabrics: Resin to fabric ratio content Target 50% +/-5% FTIR test (i.e. this is like a fingerprint test to make sure resin matches previous batches) Target 99% match Gel time target 29mins @ 140⁰F (ASTM 2471-99) Quality test performed for primer (i.e. Sikadur 340) FTIR of A and B Target 99% match Gel-time target 93 mins Viscosity Glass transition temperature goal >144 ⁰ F 96
ADVANTAGES QUALITY CONTROL 97
ADVANTAGES QUALITY CONTROL 98
ADVANTAGES QUALITY CONTROL 99
RFK BRIDGE SCOPE OF WORK Confinement wrapping of existing columns (& some beams) 30K sq.ft. Band aid for now while bridge work continues Coating of finished wrap for aesthetics and UV protection All work needs to be completed by the end of September. 112 April 8, 2019
RFK BRIDGE ORIGINAL DESIGN Designed by LIRO Group Been on the job with Sika for over 3 years & multiple phases Original design was 28 oz glass fabric Applied as a wet layup, 1 layer. Epoxy primer and saturant Contractor was awarded the job New applicator Very familiar with typical systems 113 April 8, 2019
RFK BRIDGE CONTRACTOR TRAINING CBM came into Sika to receive training on systems and applications Applied 28 oz glass fabric as a wet layup Introduced to PreSaturated Glass Fabric Immediately switch gears No longer want to saturate CBM sees major benefits Cleaner Faster Much less labor plan on only 2 man crew Glass PreSaturated Fabric was submitted to LIRO as a substitution. Submitted PDS & SDS Quickly accepted as a substitution 114 April 8, 2019
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RFK BRIDGE HOME STRETCH Only 2 days after deadline and project is complete. Inspector on job constantly has now approved all work 30K sq.ft. have been wrapped and coated Bulk of the work was done with 2-3 guys on site at a time 118 April 8, 2019
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12 Sika / PennDOT 2015 Pilot Program Condition: Cracking under the open parapet joint in Non-Composite Pre-Stressed Box Beam Bridges. Project Team: Carbon Engineering Tilden Township Upper Bern Twp Sika Corporation
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PILOT PROGRAM EVALUATION 1. PRIOR CONVENTIONS REPAIR METHODS: 2. PREVIOUSLY COMPLETED REPAIRS WERE MADE AT $1,500 - $2,500 / LINEAL FOOT 3. CUT CHIP AND REMOVE 4 PER EXPANSION JOINT (2 ON EACH SIDE OF JOINT). 4. INSTALL AND WELD SUPPLEMENTAL STEEL REINFORCEMENT. 5. RISK OF FURTHER DAMAGE TO BRIDGE. 6. INSTALL SCHEDULE COULD BE 5 7 DAYS 7. ROADWAY SHUTDOWN DURING INSTALLATION. 8. SIKAWRAP PRE-SATURATED CFRP REPAIR METHODS: 9. REPAIRS POSSIBLE WITHIN 2 DAY WINDOW. ROAD CLOSURE WAS NOT NECESSARY. 10. COMPLETED REPAIR COST OF APPROXIMATELY $450 / LINEAL FOOT MUNICIPAL LABOR. 11. COMPLETED REPAIR COST OF APPROXIMATELY $600 / LINEAL FOOT CONTRACTOR LABOR. 12. SIKAWRAP PRE-SATURATED CFRP REPAIRS 4X 5X MORE COST EFFECTIVE THAN PRIOR METHODS. 13. ALL REPAIRED BRIDGES REMOVED FROM 6 MONTH INSPECTION SCHEDULE.
UNDERWATER FRP
MOTIVATION FOR AN UNDERWATER PRODUCT DEVELOPMENT Composite have gained a wide acceptance for structural strengthening of concrete structures Most of the strengthening applications are done in dry environment due to the sensitivity of these materials to cure in the presence of moisture. There is a demand and need for an FRP system which cure in the presence of water FRP jackets have been successfully used in many projects to protect structures, however they are size specific and require a complex repair process.
RESEARCH GOALS Develop an epoxy formulation that meet following parameters Cures underwater It is environmentally safe (mix product) Minimum bond strength of 200 psi with pre-preg, with concrete failure as a desirable failure mode Work time >90 mins with >80 % cure in 5 days. Must be able to apply easily underwater Tg of the system is 150 F (66 C)
DURABILITY TEST All Samples tested retained 90% bond strength from control sample Failure Modes of most samples were 100 % cohesive on concrete Environments Durability Test Results Carbon System Polypropylene felt (psi) Glass scrim (psi) Polypropylene felt (psi) Glass System Glass scrim (psi) Control 376 336 322 288 Water resistance 356 481 425 349 Salt water resistance 348 393 374 304 Alkali resistance wet 399 476 326 289 Dry heat resistance 379 364 385 341
DURABILITY TEST CONTINUED Water Resistance Salt Water Resistance Alkali Resistance Heat Resistance
COMPRESSION TESTING Systems tested: 1 layer of 18 oz presaturated carbon 1 layer of 18 oz presatruated carbon with UWP lab cure 1 layer of 18 oz presaturated carbon with UWP underwater cure Strain gauge applied at the surface of each tested cylinder
COMPRESSION TEST RESULTS IN GRAPHICAL FORM Baseline set at 8,000 psi. There is a 6% C. Strength reduction between dry and wet applications.
IN FIELD APPLICATION
FIELD APPLICATION #2 136
FIELD APPLICATION #2 137
QUESTIONS? THANKS FOR LISTENING!