bridge (revised)

Maintenance, Inspection and Rehabilitation of Bridges

BySri A.NagendraJoint Secretary (Rtd)Karnataka PWDBangalore

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WELCOME TO ALL TRAINEES

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BRIDGES ARE NATIONAL ASSETS

THEY MUST BE MAINTAINED AND PRESERVED IN GOOD CONDITION

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THREE TYPES OF BRIDGES DEPENDING ON LINEAR WATERWAY1. CULVERTS < 6.0 m

2. MINOR BRIDGES 6.0 to 60.0 m

3. MAJOR BRIDGES > 60.0 m

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PORTIONS OF A BRIDGE1. FOUNDATION

2. SUBSTRUCTURE

3. BEARINGS

4. SUPERSTRUCTURE

5. PROTECTIVE WORKS FOUNDATION

SUB STRUCTURE

SUPER STRUCTURE

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BEARINGS

Bed Level

COMPONENTS OF A BRIDGEParapetKerbFoot pathDrainage spoutExpansion Joint Wearing coatDecking structureBearingsBearing seatPierAbutment ReturnsWell cap/Pile capFoundationsProtective Works

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COMPONENTS OF A BRIDGE (contd)Foundation Open Well Pile

Protective Works Bank Protection Embankment Floor Protection Guide Bunds

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MAINTANANCEIS DEFINED AS THE WORK NEEDED TO PRESERVE THE INTENDED LOAD CARRYING CAPACITY OF THE BRIDGE AND ENSURE THE CONTINUED SAFETY OF THE ROAD USERS.

REHABILITATIONREHABILITATION OPERATIONS AIM AT RESTORING THE BRIDGE TO THE SERVICE LEVEL IT ONCE HAD AND HAS NOW LOST OR WHICH WAS NOT ACHIEVED DUE TO DEFICIENCES IN ORIGINAL DESIGN OR CONSTRUCTION.

RETROFITTING STRENGTHENING, WIDENING, RAISING ETC., AIMING AT

IMPROVING THE LEVEL OF SERVIE BYa. LOAD CARRYING CAPAICTYb. WIDTH OF CARRIAGE WAY

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MAINTENANCE BRIDGES FORM VITAL LINK IN ANY

ROAD NETWORK. BRIDGES HAVE TO BE MAINTAINED TO KEEP IT IN TRAFFIC WORTHY CONDITION TO ENABLE UNINTERRUPTED FLOW OF TRAFFIC

SYSTEMATIC MAINTENANCE IS ESSENTIAL TO ENSURE LONG TERM DURABILITY OF BRIDGES

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OBJECTIVE OF MAINTENANCE

TO KEEP BRIDGES IN SOUND STRUCTURAL CONDITION AND SAFE

FOR TRAFFIC

WATER MUST FLOW FREELY AT ALL FLOOD LEVELS WITHOUT DAMAGING

THE BRIDGE OR WATER WAY

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MAINTENANCE CONSISTS OF

1. ROUTINE MAINTENANCE ACTIVITIES

2. PERIODIC MAINTENANCE ACTIVITIES

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ROUTINE ACTIVITIESCLEANING / CLEARINGMINOR REPAIRS LIKEPOINTING OF MASONRYPAINTINGREPAIR TO PARAPETREPLACE DAMAGED FOOTPATH SLABSCLEARING DRAINAGE SPOUTSCLEARING EXPANSION JOINTS

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PERIODIC ACTIVITIES

RETAINING WALLBED PROTECTIONRESETTING OF APRONS/PITCHINGREPLACING BEARINGSREPLACING EXPANSION JOINTS

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DEFECTS DEFECTS SHOULD BE DETECTED EARLY.

NEGLECTING CAUSES DAMAGE AND IF UNATTENDED MAY LEAD TO COLLAPSE OF STRUCTURE OR VERY EXPENSIVE REPAIRS

DEFECTS ARE AGAIN CLASSIFIED

1. MINOR DEFECTS

2. MAJOR DEFECTS

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MINOR DEFECTS1. NON-STRUCTURAL ACCUMULATION OF DIRT AND SOIL ON DECK BLOCKING OF DRAINAGE SPOUT STONE,SOIL,DIRT IN EXPANSION JOINTS DIRT AROUND BEARINGS VEGETATION CRACKING OR MOVEMENT OF APPROACH SLAB SOIL IN WEEPHOLES FLOOD DEBRIS UNDER BRIDGE DEFECTS IN CONCRETE POST AND HANDRAIL SCOUR AT FOOTING, SLOPE FAILURE

MAIN CAUSE POOR ROUTINE MAINTENANCE

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DEVELOPMENT IF NEGLECTED SLIPPERY ROAD SURFACE WHEN WET – ACCIDENTS

PONDING OF WATER ATTACKING THE STRUCTURE BY PENETRATION

DECK PREVENTED FROM DESIRED EXPANSION CONTRACTION

BUILDING OF PORE PRESSURE BEHIND ABUTMENTS -SETTLEMENT OF FILL

FIRE HAZARD IN DRY SEASON

EROSION OF RIVER BED

REMEDIESCLEANING / CLEARING

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MINOR DEFECT (contd)2. STRUCTURAL DAMAGED PARAPET MISSING FOOT PATH SLAB MISSING OR LOOSE NUT / CONNECTOR RUSTY STEEL, FADED PAINT DAMAGED WARNING SIGNS DEFECTIVE, MASONRY JOINTS MAIN CAUSES AGE ACTION OF TRAFFIC ACTION OF WATER WEATHERING SETTLEMENT POOR CONSTRUCTION

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DEVELOPMENT IF NEGLECTED

LOSS OF SENSE OF SAFETYACCIDENT FURTHER DAMAGE BY CORROSIONUNCOMFORTABLE RIDEDAMAGE TO TYRESLOCAL SETTLEMENT OF MASONRYSETTLEMENT OF APPROACHES

REMEDIES

REPLACE MISSING FOOT PATH SLAB AND PARAPETPAINTINGPOINTING MASONRYREPAIR LOOSE OR MISSING CONNECTORS

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MAJOR DEFECTS WASHING AWAY OF PROTECTIVE WORKS WASHING AWAY OF EMBANKMENT BULGING MASONRY CRACKED CONCRETE / MASONRY SPALLING OF CONCRETE SERIOUS RUST OR CHEMICAL STAINS DAMAGED EXPANSION JOINTS RUSTING OF REINFORCING STEEL OR PRESTESSING CABLE DISTORTED STRUCTURAL STEEL MEMBERS SETTLEMENT OF DECK / PIER / ABUTMENT STREAM EROSION ALL MAJOR DEFECTS SHOULD BE BROUGHT TO THE NOTICEOF THE HIGHER OFFICER IMMEDIATELY

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MAJOR DEFECTS (contd)

MAIN CAUSES

CAUSE OF MAJOR DEFECTS REQUIRE DETAILED EXAMINATION ON CASE TO CASE BASIS

REMEDIES

REHABILITATION / RECONSTRUCTION

P.S :- NATURAL CALAMITIES LIKE EARTH QUAKE, FLOOD, CYCLONE ALSO CAUSES MAJOR DEFECTS

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COMMON TOOLS USED FOR MAINTENANCE

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NOW WE WILL BE SEEING PHOTOGRAPHS OF SOME OF

THE DAMAGED BRIDGES

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COVER TO DECK SLAB SPALLED

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SETTLEMENT OF FOUNDATION

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SETTLEMENT OF FOUNDATION(AFTER RESTORATION)

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DAMAGE TO SUPER STRUCTURE

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COLLAPSE OF SUPER STRUCTURE

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CONSEQUENT COLLAPSE OF PIER

DAMAGE TO FOOT PATH SLAB

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VEGETATION GROWTH

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VEGETATION GROWTHIR-RASTA

DISPLACEMENT OF GIRDER

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CRUSHING OF WEARING COAT

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CORROSION OF REINFORCEMENT

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DAMAGED PARAPET

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DAMAGED PARAPETIR-RASTA

TRANSVERSE MOVEMENT OF DECK

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DAMAGE TO DECK SLAB

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DAMAGE TO MAIN GIRDER

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SPALLING OF CROSS GIRDERS

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LAPPING OF REINFORCEMENT IN MID SPAN

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POOR QUALITY CONCRETE

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LARGE CAVITIES IN CONCRETE

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CRUSHING OF CROSS GIRDER

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SETTLEMENT OF APPROACHES

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SOCIETY HAS RIGHT TO DEMAND ON THE ENGINEER’S SERVICES FOR THE UPKEEP OF THE STRUCTURE SO THAT IT REMAINS THERE FOR THE PURPOSE FOR WHICH IT WAS BUILT IN THE FIRST PLACE

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INSPECTION INDIA HAS THE SECOND LARGEST NETWORK OF ROADS

IN THE WORLD NEXT ONLY TO THE UNITED STATES OF AMERICA

BRIDGES FORM THE VITAL LINKS OF THE NETWORK SIGNIFICANT PROPORTION OF NATIONAL RESOURCES

IS SPENT ON ROADS AND BRIDGES DURABILITY OF INVESTMENT OF SUCH MAGNITUDE AND

IMPORTANCE IS OF PRIME CONCERN TO ALL ENGINEERS AND PLANNERS

THEREFORE IT IS NECESSARY THAT PERIODIC INSPECTIONS ARE CARRIED OUT BY RESPONSIBLE OFFICERS SO THAT TIMELY STEPS ARE TAKEN

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GUIDELINES FOR INSPECTION IRC – SPECIAL PUBLICATION – NO. 35 “GUIDELINES FOR INSPECTION AND MAINTENANCE OF

BRIDGES” IRC – SPECIAL PUBLICATION - NO. 18 “MANUAL FOR HIGHWAY BRIDGE MAINTENANCE

INSPECTION” IRC – 52 – 1998 – “BRIDGE INSPECTION REFERENCE

MANUAL” THESE MANULS PROVIDE GUIDANCE ON THE TYPE OF INSPECTION TIME AND FREQUENCY OF INSPECTION STATUS OF INSPECTING OFFICER FEATURES TO BE INSPECTED FOLLOW UP ACTION ON THE INSPECTION REPORT

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INSPECTION (contd) ORIGINAL BRIDGE REPORT TO BE MAINTAINED FOR ALL

BRIDGES ON THE BASIS OF COMPLETED DRAWINGS

FOR OLD BRIDGES BASED ON THE INSPECTION OF RESPONSIBLE OFFICER REPORT TO BE COMPILED

FOR MAJOR BRIDGES ENGINEERS ASSOCIATED WITH CONSTRUCTION OF PROJECT SHOULD ALSO PREPARE MAINTENANCE MANUAL INDICATING CRITICAL POINTS NEEDING SPECIAL ATTENTION FOR GUIDANCE OF SUBSEQUENT ENGINEERS WHO WILL BE INCHARGE OF MAINTENANCE

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TYPES OF INSPECTION

THE TYPES OF INSPECTION ARE

1. ROUTINE INSPECTION

2. PRINCIPAL INSPECTION

3. SPECIAL INSPECTION

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ROUTINE INSPECTION – THE PURPOSE IS TO DETERMINE OBVIOUS DEFICIENCIES WHICH MIGHT LEAD TO ACCIDENTS OR MAY INVOLVE HIGH MAINTENANCE COSTS IN FUTUREFREQUENCY OF ROUTINE INSPECTION SHALL BE TWICE A YEAR BEFORE MONSOON AND AFTER MONSOON

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PRINCIPAL INSPECTION THIS IS MORE INTENSIVE AND DETAILED CLOSE VISUAL INSPECTION OF ALL COMPONENTS OF

BRIDGE SUPPLEMENTED BY STANDARD INSTRUMENTATION AID INCLUDES UNDER WATER INSPECTION

FREQUENCY

FIRST PRINCIPAL INSPECTION TO BE CONDUCTED BEFORE THE EXPIRY OF DEFECT LIABILITY PERIOD BUT NOT LATER THAN 6 MONTHS AFTER COMPLETION

THEREAFTER NOT MORE THAN 3 YEARS

SHALL BE CARRIED OUT BY SENIOR LEVEL ENGINEER

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SPECIAL INSPECTION UNDERTAKEN IN THE EVENT OF UNUSUAL

OCCURANCES SUCH AS

STRONG EARTHQUAKE ACCIDENTS PASSAGE OF UNUSUAL FLOODS OR UNUSUAL LOADS HEAVY IMPACT OF FLOATING BARGES OR FLOOD

DEBRIS MAJOR WEAKNESS NOTICED DURING ROUTINE OR

PRINCIPAL INSPECTION SUCH INSPECTIONS REQUIRE GOOD DEAL OF

SUPPLEMENTARY TESTING AND STRUCTURAL ANALYSIS

GENERALLY CARRIED OUT BY EXPERTS IN THE FIELD AND SENIOR LEVEL ENGINEERS

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LENGTH OF BRIDGE STATUS OF OFFICER

UPTO 30 m30 m to 60 m

60 m to 200 m

JUNIOR ENGINEERASST. ENGINEER/ASST. EX ENGINEEREXECUTIVE ENGINEER

ABOVE 200 m AND ALL PRESTRESSED CONCRETE, CONTINUOUS BRIDGES, SUSPENSION BRIDGES, CABLE STAYED BRIDGES AND SPECIAL STRUCTURES

SUPERINTENDING ENGINEER IN ALL CASES AND IN ADDITION CHIEF ENGINEER FOR BRIDGES ABOVE 500 m IN LENGTH

INSPECTING OFFICERS

INSPECTION PROCEDURE ACTIVITIES SCHEDULED SHOUD BE PROPERLY PLANNED IN DETAIL

INCLUDING SEQUENCE OF INSPECTION SHOULD CAUSE MINIMUM INCONVENIENCE TO TRAFFIC

NO COMPONENT SHOULD BE OVERLOOKED

TYPICAL PATTERN MAY BE FOUNDATION ABUTMENTS WINGWALLS / RETURNS PIER-PIERCAP BEARINGS SOFFIT OF DECK AND BEAM DETAILS UNDER THE DECK CONDITION OF ROADSURFACE CONDITION OF FOOTPATH SLAB, PARAPET, DRAINAGE SPOUTS EXPANSION JOINTS CONDITION OF APPROACHES CONDITION OF PROTECTIVE WORKS

THE M.O.R.T.H HAS EVOLVED STANDARD PROFORMA FOR INSPECTION OF BRIDGES WHICH COVERS ALL COMPONENTS

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ACCESS FOR INSPECTIONALL THE THREE FORMS OF INSPECTION REQUIRE

APPROPRIATE MEANS OF ACCESS BUILT IN ACCESS MANHOLE BUILT IN LADDER PERMANENT CATWALK

SEMI MOBILE ACCESS SUSPENDED LADDER CATWALK SCAFFOLDING PLANKING PLATFORM

MOBILE ACCESS SKY LADDER INSPECTION GANTRY BARGES MOBILE INSPECTION UNIT

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SKY LADDER

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INSPECTION PLATFORM SUSPENDED

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INSPECTION BARGE

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MOBILE INSPECTION UNIT

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BRIDGE INSPECTION VEHICLE

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MOBILE INSPECTION UNITIR-RASTA

MOBILE INSPECTION UNIT

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INSPECTION GANTRYIR-RASTA

INSPECTION OF BRIDGES SHOULD BE CARRIED DILIGENTLY AND EARNESTLY

THIS HELPS IN FORMING PROPER REHABILITATION SCHEMES FOR WEAK BRIDGES

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REHABILITATION BRIDGE STRUCTURES DURING THEIR SERVICE LIFE MUST

HAVE A SPECIFIED LEVEL OF SAFETY AND SERVICE ABILITY UNDER DESIGN LOADS AND ANTICIPATED CONDITIONS OF USE

BRIDGES, HOWEVER, GENERALLY DETERIORATE WITH PASSAGE OF TIME DUE TO

AGING AND WEATHERING INADEQUATE MAINTENANCE INADEQUACIES IN DESIGN AND DETAILING MISHAPS AND ACCIDENTS CHANGE OF HYDRAULIC AND LIVE LOAD PARAMETERS

DURING SERVICE DAMAGES DUE TO EXTERNAL CAUSES LIKE FLOOD, FIRE,

EARTHQUAKE AND FOUNDATION SETTLEMENT

REHABILITATION AIMS AT RESTORING THEBRIDGE TO THE SERVICE LEVEL IT ONCE HAD AND HAS NOW LOST

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TYPES OF BRIDGES VARIOUS TYPES OF BRIDGES MASONRY BRIDGES – STONE/BRICK R.C.C BRIDGES STEEL BRIDGES COMPOSITE CONSTRUCTION PRESTRESSED CONCRETE BRIDGES TIMBER BRIDGES FORMS OF BRIDGES ARCH – MASONRY CONCRETE STEEL GIRDERS WITH CONCRETE DECK SLAB R.C.GIRDERS WITH DECK SLAB BOX GIRDERS R.C.C.RIGID FRAME P.S.C.GIRDERS AND DECK SLAB P.S.C. BOX GIRDERS

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NORMALLY OBSERVED DISTRESS ARCH BRIDGES CHANGE IN PROFILE OF ARCH LOOSENESS OF MORTAR MOVEMENT OF ABUTMENT/PIER LONGITUDINAL CRACKS LATERAL AND DIAGONAL CRACKS CRACKS BETWEEN ARCH RING SPANDREL OR PARAPET WALL VERTICAL CRACK IN THE RETRUN WALL BULGING OF WALL R.C.C BRIDGES CRACKING SCALING DELAMINATION SPALLING LEACHING STAINS HOLLOW OR DEAD SOUND DEFORMATIONS HOLE IN DECK SLAB PRESTRESSED CONCRETE BRIDGES CRACKING LEACHING STAINS SPALLING DEFORMATION ABNORMAL VIBRATION

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STEPS INVOLVED IN WORKING OUT A REHABILITATION PROJECT

EVALUATION OF STRUCTURE FROM AVAILABLE DOCUMENTS AND INSPECTION

LOCATING DAMAGES/DEFECTS/DESTRESS ANALYSIS OF CAUSES OF

DAMAGES/DEFECTS/DISTRESS EVALUATION OF RESULTS OF STRUCTURAL

ASSESSMENT DESIGN OF REPAIRS FOR

REHABILITATION/STRENGTHENING FRAMING PROPOSALS AND ESTIMATION OF COSTS FIXING OF AGENCY CARRYING OUT REHABILITATION WORK

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TECHNICAL APPROACH FOR REHABILITATION

STRATEGY FOR DETERMINATION IS IN THE LIGHT OF

THROUGH INVESTIGATION DIAGNOSIS OF THE CAUSES OF DETERIORATION,

FAULT, WEAKNESS ASSEESSMENT OF CURRENT CONDITION OF

BRIDGE REPAIR AND STRENGTHENING SHOULD BE

STRUCTURALLY AND CHEMICALLY COMPATIBLE WITH THE ORIGINAL STRUCTURE

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EVOLUTION OF REHABILITATION TECHNIQUES

WITH THE GROWTH OF STRUCTURES INVOLVING COMBINATION OF CONCRETE AND STEEL, PROBLEM OF FUNCTIONALLY SATISFACTORY AND STRUCTURALLY DEFICIENT STRUCTURES AROSE

THIS LED TO THE SCIENCE OF REHABILITATION, WHICH IS RELATIVELY NEW COMPARED TO DESIGN AND CONSTRUCION

REHABILITATION DEMANDS KNOWLEDGE OF DESIGN,DETAILING, CONSTRUCION CHEMISTRY OF MATERIALS, DIAGNOSTIC TECHINQUES, HIGHLEVEL OF ENGINEERING AND SUPERVISION

SUCCESSFUL IMPLEMENTATION OF A REHABILITATION PROGRAM INVOLVES WORK OF MULTIDISCIPLINARY TEAM OF SPECIALISTS FOR INVESTIGATION, DIAGNOSIS, ENGINEERING AND SUPERVISION

CONTINUOUS MONITORING DURING REHABILITATION AND SUBSEQUENT SERVICELIFE IS MANDATORY

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TESTING AND DIAGNOSIS INVESTIGATION PRIOR TO INVESTIGATION AVAILABLE DRAWINGS MUST

BE STUDIED TO IDENTIFY VULNERABLE DETAILS INVESTIGATION IS CARRIED OUT IN THREE LEVELS• VISUAL METHODS – USEFUL IN DETECTING CRACKING, SCALING

RUSTING, WEARING, ABRASION DAMAGES• GENERAL SURVEY – WITH LIMITED PHYSICAL TESTS TO PLAN FOR

MORE DETAILED INVESTIGATION AND POSSIBLE REHABILITATION• DETAILED TESTING CONSISTING OF ELECTRICAL AND CHEMICAL METHODS – FOR DETECTING CORROSSION ULTRASONIC METHODS – FOR CRACK DETECTION THERMOGRAPHY AND RADAR TECHNIQUE – FOR DETECTING

DELAMINATION AND SCALING BELOW WEARING COAT RADIOGRAPHY – FOR DETECTING VOIDS IN THE GROUT

IRC – SP – 40 – GUIDELINES FOR REHABILITATION OF STRUCTUES GIVES ELABORATE LIST OF TESTS

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TO ASSESS THE EXTENT OF DISTRESS AND PRESENT CONDITION OF BRIDGES FOLLOWING STUDIES ARE CONDUCTED

STUDY PURPOSE

1. DIMENSIONAL MEASUREMENT OF ALL ELEMENTS OF BRIDGE STRUCTURE

2. CORE EXTRACTION (CST)

TO OBTAIN ACCURATE MEASUREMENTS OF ALL COMPONENTS AND TO PREPARE DRAWING REQUIRED FOR ARRIVING AT METHODS OF RESTORATION

TO ASSESS THE STRENGTH OF INSITU CONCRETE AND FOR VERIFICATION OF RESULTS OF OTHER METHODS OF NON DESTRUCTIONVE TESTING

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STUDY PURPOSE

3. ULTRASONIC PULSE VELOCITY TEST (UPVT)

4. REBOUND HAMMER TEST(RHT)

TO ASSESS THE QUALITY OF CONCRETE IN GENERAL. DETERMINATION OF UNIFORMITY OF CONCRETE, INTERNAL CRACKING, HONEY COMBING.THE EQUIPMENT IS KNOWN AS “PUNDIT” (PORTABLE ULTRASONIC NONDESTRUCTIVE DIGITAL INDICATING TESTER)

ASSESSING THE QUALITY OF COVER CONCRETEBASED ON SURFACE HARDNESS. HIGHER THE REBOUND NUMBER HIGHER THE STRENGTH.

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STUDY PURPOSE

5. COVER METER TEST (CMT)

6. HALF CELL POTENTIAL MEASUREMENT TEST

(HCPT)

7. ENDOSCOPIC STUDY

BASED ON ELECTRO MAGNETIC PRINCIPLES TO ASSESS THE COVER PROVIDED. LOCATING AND MAPPING OF REINFORCEMENTS

MEASURED IN TERMS OF MILLIVOLTS WITH REFERENCE TOA REFERENCE ELECTRODE. TO DETERMING THE RATE OF CORROSION OF REINFORCEMENT

WORKS ON THE PRICIPLE OF LIGHT SOURCE THROUGH OPTIC FIBRES. TO STUDY CAVITY, PITTING OF EMBEDDED REINFORCEMENT GROUTING QUALITY OF H.T.CABLES

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STUDY PURPOSE8. CARBONATION TEST

9. CHLORIDE DETERMINATION TEST

10. SULPHATE DETERMINATION TEST

TO DETERMINE THE DEPTH OF CARBONATION IN R.C.ELEMENTS

TO ESTIMATE THE LEVEL OF CHLORIDES IN CONCRETE.PRESENCE OF HIGHER AMOUNT OF CHLORIDES SURROUNDING THE REINFORCEMENT CAUSES CORROSION

TO ESTIMATE THE LEVEL OF SULPHATE IN CONCRETE.PRESENCE OF HIGHER AMOUNT OF SULPHATES WILL RESULT IN REACTION WITH CALCIUM CAUSING DETERIORATION OF CONCRETE.

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STUDY PURPOSE11. LEVEL OF pH IN CONCRETE LEVEL OF pH IN FRESH

CONCRETE IS GENERALLY 12 TO 14. IF THE pH VALUE OF HARDENED CONCRETE REDUCES IT INDICATES THAT CONCRETE IS CARBONATED WHEN pH VALUE FALLS BELOW 10 ALKALANITY WILL NOT BE ADEQUATE TO PROTECT AGAINST CORROSION

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RESULTS CAN BE SUMMARISED AS

• MECHNICAL PROPERTIES

• CHEMICAL PROPERTIES

• PHYSICAL CONDITION

• EXTERNAL MANIFESTATION

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NON DESTRUCTIVE TESTS NECESSARY FOR CONDUCTING NON DESTRUCTIVE

TESTING FOR CONDITION ASSESSMENT OF BRIDGES HAS GROWN CONSIDERABLY IN RECENT TIMES DUE TO INCREASING NUMBER OF BRIDGES SHOWING SIGNS OF DISTRESS

A LARGE VARIETY OF TECHINQUES AND METHODS ARE BEING DEVELOPED ALL OVER THE WORLD TO ASSESS MATERIAL PROPERTIES AND STRUCTURAL RESPONSE

SCOPE, APPLICABILITY, AND ACCURACY VARY CONSIDERABLY FROM INSTRUMENT TO INSTRUMENT

NON DESTRUCTIVE TESTING IS SUPPLEMENTARY TO VISUAL INSPECTION

IT IS A GROWING FIELD OF SCIENCE AND HAS GREAT SCOPE FOR RESEARCH AND DEVELOPMENT

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SCHMIDT HAMMER TEST

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CONCRETE CORE EXTRACTION

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PROFOMETER TEST

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ULTRASONIC TESTS

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HALF CELL POTENTIAL TEST

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CHLORIDE PENETRATION TEST

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ENDOSCOPE TESTIR-RASTA

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REPAIRS AND STRENGTHENING TECHNIQUES

CRITERIA FOR SELECTION OF MATERIALS AND TECHNIQUES FOR REPAIRS AND STRENGTHENING COULD BE

CAUSES OF DISTRESS EFFICIENCY OF THE MATERIALS AND TECHNIQUES IN THE

PRESERVATION AND/OR ENHANCING LOAD CARRYING CAPACITY OF THE STRUCTURE

AVAILABILITY OF MATERIALS AND EQUIPMENT IMPORTANCE OF THE BRIDGE TIME AVAILABILITY LIFE EXPECTANCY FEASIBILITY OF TRAFFIC DIVERSION

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REPAIRS TO FOUNDATIONS FOUNDATION REPAIRS HAVE TO BE TREATED ON CASE TO CASE

BASIS. EACH CASE HAS TO BE ANALYSED INDIVIDUALLY AND MAY REQUIRE SPECIAL INVESTIGATIONS

SOME EXAMPLES SCOUR AND EROSION PROTECTION REPAIR OF PROTECTIVE WORKS REPAIR OF FOUNDATION BUILT ON SOFT GROUND SUBJECT TO

EROSION STRENGTHENING OF FOUNDATIONS EXTENDING EXISTING FOUNDATIONS REPAIR OF UNDER WATER STRUCTURES REPAIR OF SERRATIONS ON THE SURFACE CAUSED BY HIGH VELOCITY

OF PARTICLES IN THE WATER UNDER WATER WORK PROPERLY TRAINED AND EQUIPPED PERSONNEL TO BE DEPLOYED SOPHISTICATED TECHNIQUES LIKE ULTRASONIC THICKNESS GUAGE,

COMPUTER TOMOGRAPHY, ACOUSTIC MICROGRAPY ARE BEING INCREASINGLY ADOPTED

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REPAIRS TO MASONRY STRUCTURES LOSS OF BOND FOR CROWN STONEFLAT JACKS ARE USED FOR PUSHING THE STONE TO ORIGINAL

POSITION LOW PRESSURE CEMENT GROUTING IS DONE TO STRENGTHEN OLD MORTAR

LONGITUDINAL CRACKS ALONG THE DIRECTION OF TRAFFICFOR SMALLER DEPTH OF CRACKS RAKE THE MORTAR JOINTS AND REFILL WITH CEMENT MORTARIF DEPTH OF PENETRATION IS MORE IT IS BETTER TO ADOPT FINE

CEMENT INJECTION(GROUTING) FOR REMEDIAL MEASURESGENERALLY IT IS CHEAPER AND BETTER TO GROUT THE CRACKS WITH

CEMENT THAN WITH EPOXY TRANSVERSE CRACKSINJECTION OF CEMENT WILL PROVIDE A GOOD BOND BETWEEN STONE

OR BRICK MASONRY STRENGTHENING OF ARCH RINGSBY ADDING MATERIALS TO INTRADOS AND EXTRADOS

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REPAIRS AND STRENGTHENING TECHNIQUES FOR CONCRETE BRIDES

REPAIR WORKS NOT REQUIRING STRENGTHENINGTHIS MAY BE CATEGORISED AS REPAIR OF CONCRETE SURFACE REPAIR OF CONCRETE CRACKS REPAIR OF CORRODED REINFORCEMENT REPAIR OF HIGH TENSILE STEEL REPAIR OF POROUS CONCRETE AND HOLES PREREQUISITE FOR REPAIR OF CONCRETE SURFACE IS REMOVAL

OF LOOSE DAMAGED AND FRACTURED CONCRETE BY MECHANICAL METHODS HYDRAULIC METHODS NORMALLY USED MECHANICAL METHODS ARE MILLING, CHIPPING,

SANDBLASTING AND COMPRESSED AIR CLEANING HYDRAULIC METHODS SUCH AS WATER JETTING ARE PREFERABLE TO

JACK HAMMERS FOR PREVENTING DAMAGE 10 – 40 MPa – REMOVAL OF LOOSE PARTICLES, VEGETATION, STAINS 40 – 120 MPa – REMOVAL OF LOOSE CONCRETE 120 – 240 MPa – DEMOLITION, CUTTING

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RESTORATION MATERIALS

Several restoration materials have been developed in the recent past,which ensure safe and durable restorations. A few of them are -

Modified Mortars. Epoxy Mortars. Cementitious/Epoxy Grouts. Membrane/Protective Coatings. Glass Fiber / Carbon Fiber wrappings Free Flow Micro Concrete. (Super Fluid Micro Concrete)

Free Flow Micro Concrete is an ideal material for encasement / Substitution systems

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Repair materialsApplication / purpose Speciality chemicals

Corrosion protection Anticorrosive zinc rich coatings, corrosion inhibiting admixtures, permeability reducers like plasticisers and superplasticisers etc.

Bonding aids Acrylic, Styrene Butadiene rubber, epoxies

Additives for grouting / gunniting, shotcreting

Cement based

Prepacked mortars Polymer modified cement based, epoxy based etc.

Shrinkage compensating microconcrete

Cement based

Injection grouts for sealing cracks, pores

Low viscous epoxies, polyurethane’s, cement based

Underwater repairs Epoxy, cement based

Sealing compounds Epoxies, polyurethanes, polysulphides, silicones

Instant plugging mortar Cement based

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Putties Cement, epoxy based

Anchoring grouts Polyester resin based

Underwater putty Epoxy based

Chemical resistant screed Epoxy based

Mortars / concretes Epxoy, cement based

Anticarbonation coatings Aliphatic, acrylate based

Chemical resistant coatings Epoxy, polyurethane based

Electrochemical range of products like sacrificial zinc anodes, Life jackets, Electrochemical chloride extraction and Realkalisation etc.

Strengthening of structures Composite fibre wrapping

Waterproof slurries / coatings Polymer and cement based epoxy based.

Special concretes Microconcretes, epoxy concretes, latex concretes, polymer modified cements, sulpher concrete, fibre reinforced concrete, shrinkage compensating concretes etc.

Repair materialsApplication / purpose Speciality chemicals

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Popular Restoration Techniques

1. Substitution techniques

2. Encasement techniques

3. Wrapping-Round techniques

4. Shortcreting techniques

5. Pressure grouting

6. Prestressing techniques

7. Material Strengthening techniques

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Sl.No. Repair Technique Distress addressed Materials used

1 Injection grouting Seal cracks and pores in concrete.Arrest leakages

Epoxies / Polyurethane Cement also used

2 Guniting / shotcreting Replace cover concreteReinstate locally damaged areasBuild up thickness in overhead situations

Gunites / shotcretes and admixtures

3 Jacketing Reinstatement of extensively damaged concrete members, strengthening for load enhancement

Concrete with water reducing / Shrinkage compensating admixtures

4 Stitching Repair of cracked concrete Holes grouted with epoxy / polyester / cement with nonshrink additives

5 External prestressing For cracked concrete members HTS bars + anchors

6 Microconcrete encasement

Extensively damaged concrete beams and columns. Enhance load carrying capacity. Increase flexural rigidity

Shrinkage compensating, free flow microconcretes

7 Epoxy steel plate bonding

Strengthening weakened members. Reduce deflection

Anchor grout / epoxy for bonding

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8 Underwater repairs Cracks under water strengthening of structures, reinstatement of worn out areas, localised damages etc.

Under water admixtures, anti washout microconcretes, moisture insensitive epoxy resins and putties

9. Patch repairs Localised reinstatement of worn out concrete

Polymer modified / latex modified mortars, epoxy mortars

10. Composite fibre wrapping Strengthening of distress / weakened concrete members, seismic retrofitting

E-glass / carbon / armid fibres with epoxy primer and saturant

11. E-chem repairs Long-term corrosion protection. Prevention of formation of incipient anodes

Sacrificial anodes / Life jackets

12. General grouting To densify porous concrete slabs, retaining walls etc.

Non shrink, plasticising, additives

Repair Techniques

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STRENGTHENING OF CONCRETE STRUCTURES

STRENGTHENING OF STRUCTURAL MEMBERS CAN BE ACHIEVED BY

REPLACING POOR QUALITY OR DEFECTIVE MATERIAL BY BETTER MATERIAL PROVIDING ADDITIONAL LOAD BEARING MATERIAL REDISTRIBUTION OF THE LOADING ACTIONS THROUGH IMPOSED

DEFORMATION OF THE STRUCTURAL SYSTEM NEW LOAD BEARING MATERIAL WILL USUALLY BE HIGH QUALITY CONCRETE REINFORCING STEEL BARS THIN STEEL PLATES AND STRAPS POST TENSIONING TENDONS VARIOUS COMBINATIONSDESIGN ASPECTSSHOULD BE DESIGNED AND CONSTRUCTED AS PER APPROPRIATE

CODESTYPICAL PROBLEMS WILL BE TRANSFER OF SHEAR FORCES BETWEEN OLD AND NEW CONCRETE POST TENSIONING OF EXISTING STRUCTURE WHICH IS SLIGHTLY

DIFFERENT FROM POST TENSIONING OF NEW STRUCTURE

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STRENGTHENING OF REINFORCEMENTSTRENGTHENING OF REINFORCEMENT SUBJECT

TO TENSILE FORCE CAN BE ACHIEVED BYREPLACING REINFORCEMENT SEVERELY

DAMAGED BY CORROSIONADDITIONAL REINFORCEMENT PLACED IN THE OLD CROSS SECTION PLACED IN AN ADDITIONAL CONCRETE LAYEREPOXY BONDED STEEL PLATES

THE STRENGTHENING WITH STEEL PLATE AND EPOXY IS WORKMANSHIP SENSITIVE AND SHOULD BE DONE UNDER EXPERT GUIDANCE ONLY

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STRENGTHENING TO INCREASE LOAD CARRYING CAPACITY

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STRENGTHENING THE SHEAR ZONE

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STRENGHTENING THE STEEL GIRDERS

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STRENGTHENING WITH SUPPLEMENTARY PRESTRESSING

STRENGTHENING BY MEANS OF SUPPLEMENTARY PRESTRESSING IS AN EFFECTIVE METHOD. BOTH R.C.C AND P.S.C STRUCTURES CAN BE STRENGTHENED

ONLY POST TENSIONED SYSTEMS ARE BEING ADOPTED USE OF LOWER STRENGTH, HIGHER DUCTILITY THREADED

BARS WOULD BE SIMPLE. ROBUST AND DURABLE AVOIDS HIGH COST OF ANCHORAGES

DESIGNED AS NORMAL POST TENSIONED GIRDER EXCEPT THAT EFFECT OF CREEP AND SHRINKAGE FOR OLD CONCRETE IS FAR LESS

POST TENSIONING TENDONS SHOULD BE PROTECTED AGAINST COROSION AND FIRE TO THE SAME EXTENT AS IN A NEWLY BUILT STRUCTURE

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ANCHORAGE WITH AUXILIARY STEEL FRAME

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ANCHORAGE OF SUPPLEMENTARY PRESTRESSING ELEMENTS WITH

ADDITIONAL SUPPORTS

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ANCHORAGE OF SUPPLEMENTARY PRESTRESSING ELEMENTS AT THE END

OF THE GIRDER

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PROFILE OF EXTERNAL PRESTRESSED CABLE

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EXTERNAL PRESTRESSED CABLE

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DEFLECTOR FOR CABLE SUPPORT

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MONITORING IT IS ESSENTIAL TO KEEP THE REHABILITATED STRUCTURE UNDER

OBSERVATION AND ITS CONDITION MONITORED REGULARLY ON A SPECIFIED FORM AND INSPECTIONS ARE CARRIED OUT ACCORDING TO A CALENDER

MONITORING ALSO INVOLVES CARRYING OUT CERTAIN LABORATORY AND FIELD TESTS AS WELL AS CONDITION SURVEYS AND MEASUREMENTS TO DETECT EVEN SMALL STRAINS, MOVEMENTS, CHANGES IN REACTION AND DEFORMATIONS

FREQUENT PRINCIPAL INSPECTIONS SHOULD BE CARRIED OUT SPECIAL ATTENTION SHOULD BE GIVEN TO CORROSION

MONITORING AFTER COMPLETION OF EACH JOB OF REHABILITATION, ENGINEER

MUST PREPARE A DOCUMENT TO ENABLE DRAWING LESSONS FOR THE FUTURE AND TO IMPROVE BRIDGE TECNOLOGY

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BRIDGE MAINTENANCE AND MANAGEMENT IN FUTURE

EVERY STATE IN THE COUNTRY IS BURDENED WITH A NUMBER OF OLD BRIDGES ON ITS ROAD NETWORK MAINTENANCE NEEDS FOR OLDER BRIDGES HAS OUTSTRIPPED AVAILABLE RESOURCES

THE SITUATION DEMANDS NEED FOR IMPROVED REPAIR AND REHABILITATION TECHNIQUES AND ALSO COMPREHENSIVE APPROACH TO BRIDGE MANAGEMENT

THE INDIAN ROADS CONGRESS, MINISTRY OF ROAD TRANSPORT AND HIGHWAYS, THE STATE PUBLIC WORKS DEPARTMENT ARE WORKING TO DEVELOP BRIDGE MANAGEMENT SYSTEMS INTEGRATING THE DISCIPLINES OF STRUCTURAL ENGINEERING, CHEMICAL TECHNOLOGY, INSTRUMENTATION TEHCNOLOGY, OPERATIONS RESEARCH, ECONOMICS PLANNING AND INFORMATION TECHNOLOGY

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BRIDGE MAINTENANCE(CONTD.) A CENTRAL AUTHORITY IN EACH STATE SHOULD

INSPECT AND INVENTORISE ALL THE BRIDGES ON THE NETWORK. THIS WILL HELP THE DECISION MAKERS FOR OBTAINING TIMELY AND QUALITY DATA ABOUT BRIDGE CONDITIONS. PROJECT COSTS AND FEASIBILITY INSPECTION AND INVENTORISING IS A MAMMOTH PROGRAM AND SHOULD BE DONE IN A PLANNED AND METICULOUS MANNER

IN FUTURE BRIDGE INSPECTION WILL FOCUS ON THE QUANTITATIVE ASSESSMENTS OF BRIDGE PERFORMANCE AND CONDITIONS RATHER THAN VISUAL INSPECTIONS AND CONDITION RATINGS

A VARIETY OF PERMANENT SENSORS ON BRIDGES WILL COLLECT DATA AT MANY POINTS. THESE SENSORS WILL BE POWERED BY – AND REPORT TO WIRELESS NETWORKS. DATA WILL BE ANALYSED AND DETERIORATION WILL BE DETECTED AUTOMATICALLY

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WHEN PROBLEMS ARISE, ENGINEERS WITH KNOWLEDGE AND EXPERIENCE WILL BE ABLE TO ACCURATELY ANALYSE THE STRUCTURAL CONDITION AND FORMULATE CORRECTIVE STRATEGIES

TECHNOLOGY WILL GREATLY ENHANCE THEIR ABILITY TO MAKE THESE ASSESSMENTS

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BRIDGE MAINTENANCE(CONTD.)

BRIDGE MAINTENANCE AND REPAIR

HITHER TO REPAIR OF BRIDGES HAS BEEN A REACTIVE ACTIVITY INITIATED ONLY WHEN DETERIORATION THREATENS SAFETY

THE BRIDGE MANAGEMENT SYSTEM WANTS TO EMPHASIZE COST-EFFECTIVE & PROACTIVE ACTION FROM THE TIME WHEN BRIDGE IS NEW.

FUTURE FOCUS WILL BE PREVENTIVE MAINTENANCE. INCREASE IN SERVICE LIFE WILL BE THROUGH ROUTINE ACTIVITIES LIKE CLEANING OF BRIDGE COMPONENTS, OVERLAY RENEWAL, MAINTAINING INTEGRITY OF JOINT SEALS, IMMEDIATE PAINTING OF STEEL

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• FUTURE APPROACH

APPROACH TO BRIDGE MAINTENANCE IS INCREASINGLY INFLUENCED BY BRIDGE MANAGEMENT SYSTEMS. FUTURE STRATEGY INCLUDES LIFE-CYCLE COST ANALYSIS AND INCORPORATION OF USER COST INTO MAINTENANCE DECISIONS

BRIDGE MAINTENANCE ENGINEERS WILL USE AN ARRAY OF INCRESINGLY SOPHISTICATED INSTRUMENTS PROCEDURES AND

SYSTEMS TO EVALUATE, REPAIR AND REHABILITATE STURCTURES

RESEARCH IN MATERIALS WILL CONTINUE WITH EMPHASIS ON PRODUCTS SUCH AS NON CORRODING REINFORCEMENTS, IMPERMEABLE CONCRETE SUPERIOR COATINGS THAT WILL DRASTICALLY BRING DOWN MAINTENANCE REQUIREMENTS WHEN USED IN NEW CONSTRUCTION

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BEST BRIDGE IN THE WORLD?

FRIENDSHIP

MAINTAIN IT

THANK YOU

bridge (revised)

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