SRI JAYACHAMARAJENDRA COLLEGE

OF ENGINEERINGDEPARTMENT OF CIVIL ENGINEERING

MYSORE-570006(Vishweshwaraiah Technological University)

SEMINAR REPORT ON

“MAINTENANCE OF BRIDGES”

BY

YOGANANDA.K.N

4JC02CV050

SR No. 02258

VIII Semester, CIVIL ENGINEERING,

DEPARTMENT OF CIVIL ENGINEERING

SRI JAYACHAMRAJENDRA COLLEGE OF ENGINEERING

(AFFILIATED TO VISVESWARAIAH TECHNOLOGICAL UNIVERSITY, BELGAUM)

MYSORE - 570 006

CERTIFICATE

This is to certify that ‘MAINTENANCE OF BRIDGES’ is a bonafied seminar

report submitted by Mr. YOGANANDA.K.N. bearing USN 4JC02CV050 on partial

fulfillment for the award of degree, in CIVIL ENGINEERING of Vishveshwaraiah

Technological University, Belgaum during the year 2005.

Examiners Signature of the HOD

1. Dr. Syed Shakeeb-Ur-Rahman

Professor and Head

2.

SYNOPSIS Ever since the time of Romans, there has been a continuous effort by Research

workers in the field of Construction of Bridges, maintenance of bridges to withstand for

many years.

Today we can construct a bridge having larger spans with minimum columns etc.

Today we construct bridges using concrete, steel etc. By proper maintenance the life of

the bridge can be increased to its maximum extent.

After the construction of bridges, it should be verified once in a month for any

occurrence of defects. If so, it is rectified. Proper records should be maintained for every

bridge. The bridges should be thoroughly inspected by using sophisticated equipments if

it is required to replace the bridge components it is done immediately.

A brief report on how to inspect the bridges & maintain the bridges are discussed in this report.

MAINTENANCE OF BRIDGES

INTRODUCTION: For safe & uninterrupted traffic flow, it is necessary to have the maintenance of

bridges periodically. This maintenance is essentially consists of structural maintenance,

rehabilitation & replacement. It provides the guidelines for the engineers to adopt cost

effective decisions regarding maintenance work for bridges, canals, tunnels etc & it can

be achieved by the optimal use of public funds. To achieve the desired result requires

constant alertness & thorough inspection procedures.

WHY WE NEED TO MAINTEIN BRIDGES.

It is necessary for the following factors,

1.COST

2.LIFE TIME.

3.VERY IMPORTANT STRUCTURE.

4.PURPOSE.

5.ECONOMY.etc

A Bridge constitutes a huge investmental structure a little Recklessness in its

maintenance will be a costly affair.The bridge life has to be considered in more detail as

its Longevity will relate directly to its function.hence effective maintenance will lengthen

the bridge life and also cut out the problem of reconstruction which involves great risk.

Bridges forms an integral part of transportation hence require constant maintenance.As

bridges are constructed for a particular purpose, maintenance factors will keep this

purpose alive.

QUALIFICATIONS OF INSPECTION PERSONNEL: The individual incharge of the bridge should have the following qualifications & should carry out the following responsibilities.

1 He should be a qualified Engineer having 10 years experience in bridge constriction & inspection

2 He shall be responsible for thorough field inspections & recommendations for correction of defects, posting of restricted load or traffic etc.

3 He must be very familiar with design & construction features of the bridge & he must be capable of analyzing the structural deficiency, taking serious actions to over come it.

CATEGORIES OF BRIDGE INSPECTIONS: The following are the categories of the bridge inspections.

1. Routine inspection

2. Detailed inspection

3. Special inspection

1. Routine Inspection: This inspection is a general inspection & it is to be carried out every month to

check the fairly obvious deficiencies which could lead to accidents or future major

maintenance or maintenance problems.

2. Detailed Inspection: This inspection is done in two categories namely “general” defined by “frequency”

& “major” defined by “intensity of inspection” respectively. General inspection is to be

done at yearly intervals & it should cover the all elements of the structures against a

prepared checklist. It is an visual inspection with standard instruments & a detailed report

has to be prepared. The major inspection should be more intensive & would required

detailed inspection of all elements. This inspection can be done in between two & three

years.

3. Special Inspection: This inspection is undertaken to cover special circumstances such as natural

calamities like earthquake, unusual floods, high intensity loadings etc.It is important that

inspections are undertaken in those periods which offer the most critical evaluation of the

performance of the structure. The frequency of routine inspections can be determined by

the importance of the structure, environmental conditions & cost. A comprehensive

checklist of items related to the form, material, conditions & situation of the structure,

should be made.

ACCESS FOR INSPECTION: The accessibility can be successfully achieved by Snooper-crawlers, which are

movable vehicle-mounted crane arms, tailored to the needs of horizontal & vertical

accessibility all along the span, substructure & bearings. For very long span, wide bridges

with large navigational clearances, like the cable stayed suspension system or steel girder

type, permanently installed traveling gantries and lifts are a must for inspection. For piers

& pier frame of large height & bearings must be provided from the deck.

EQUIPMENTS NEEDED FOR THE INSPECTION PURPOSES:1 Snooper-Crawler & adjustable ladders.

2 Rebound hammer for in situ assessment of the strength of concrete.

3 Magnetic detector for measuring thickness of concrete cover, & for locating

reinforcement bars.

4 Acoustic crack detector & magnetic crack definer for detection & location of

cracks in steel.

5 Mechanical extensometer & transparent templates for reading off crack widths

from surface contact.

6 Hydraulic devices, pressure transducers or load cells for measurement of forces or

pressures etc.

7 Equipment for measuring vibrations.

8 Electrical resistance meter.

The measurement of the performance of a bridge depends on the following

elements.

1. Standard loading conditions

2. Type of structure relative to its intended use.

3. Functional classification of highway.

4. Safety.

For standard loading conditions, an evaluation of current design loading criteria

should be made to arrive at a recommended system of desired load capabilities of various

types of bridges.

The type of structure or intended use category represents the purpose of or the

need of the structure. Bridging of waterways, valleys, railroads, passage of storm water

runoff, tunnels are comes under this category.

Functional classification of the highway containing the bridge will be considered

as a part of Sufficiency rating & its classification are as follows.

a) Major limited access highways

b) Primary arterial roads

c) Secondary arterial roads

d) Collector roads

e) Local or minor roadways

In considering the safety factor, existing geometric information has to be

tabulated to form standards for desired levels of structure user safety. The

following are the typical items which might appear as follows:

a) Stopping sight distance

b) Structure roadway

c) Approach roadway

d) Vertical clearance over roadway

e) Vertical clearance below the superstructure

f) Median or lane separation

g) Curve data

h) Railings & Parapets

i) Impact attenuating devices

The conditions which have been formulated for analysis of bridge is Condition

rating system & Sufficiency rating system.

CONDITION RATING SYSTEM:1 Structures containing elements which are in good condition without any signs of

deterioration & requiring no immediate action.

2 Structures containing elements which show signs of distress but which, under the

operating conditions of the total structure may not having a serious defect & it

can be rectified easily.

3 Structures containing elements which show signs of deterioration & which, due

to distress under operating conditions, would affect structural integrity of the

elements.

4 Structures containing elements which show signs of progressive failure due to

excessive loading, possibly resulting in use limitations or replacement.

5 Structures containing elements which have been under designed or poorly

constructed or are overloaded & show cracks or deterioration.

This rating system is explained in the following table Sl. No.

Descriptions Rating

01 Not applicable N

02 New condition 9

03 Good condition (No repairs needed) 8

04 Generally good condition (Potential exists for minor maintenance) 7

05 Fair condition (Potential exists for major Maintenance) 6

06 Generally fair condition (Potential exists for minor rehabilitation) 5

07 Marginal condition (Potential exists for major rehabilitation) 4

08 Poor condition (Repair or rehabilitation required immediately) 3

09 Critical condition (Need for repair or rehabilitation is urgent. Facility should be closed until the indicated repair is complete

2

10 Critical condition (Facility is closed. Study should determine the feasibility for repair

1

11 Critical condition (Facility is closed & is beyond repair 0

SUFFICIENCY RATING SYSTEM: In the area of performance, a numerical representation can be developed. This

system is used in the following areas.

a) Load performance

b) Safety performance

c) Remaining life

CONDITION SURVEY:

Each bridge should be classified, inspected, & evaluated in relation to the various

parameters which affect the structural integrity & performance characteristics of the

structure. The primary goal is to achieve uniform interactive parameters to inspect

bridges.

STRUCTURE IDENTIFICATION: This is done to establish a uniform code number for each structure, which relates

the structure location with respect to highway, district, highway route number & the

number of kilometers from an established base point of the highway on which the

structure is located.

The type of bridge crossing should be noted & coded as a supplementary

identification. Some of the crossings are identified as follows.

1 Over water course

2 Over highway

3 Over railway line

4 Over land feature

For identifying the type of crossing, the structure should be identified by name.

Once the preliminary identification of the structure & crossing type has been established,

the identification of the type of structure should be made.

Following table will give the three digit code for the identification of Type of

Structure.

Type of StructuresSl.No. 1st Digit 2nd & 3rd Digits

01 Reinforced concrete, determinate Slab02 Reinforced concrete, continuous Stringer/Multi-beam or girder steel03 Steel, determinate Girder & floor beam system04 Steel, continuous Tee beam

05 Prestressed concrete, determinate Box beam or Girder – multi

06 Prestressed concrete, continous Box beam or girder – single

07 Timber Frame

08 Stone or masonry Orhtotropic

09 Aluminium Truss – deck type

Truss – through type

Arch deck type

Arch through type

Suspension

Stayed girder

Movable lift type

Movable-bascule type

Movable swing type

Tunnel

Culverts

Others

APPROACH TO THE BRIDGES:1. Alignment

2. Grade

3. Approach slabs

4. Guard rail

5. Embankment condition

6. Relief joints

Each component of the bridge should be analyzed for structural deficiencies and

deterioration. Concrete structural components warrant inspection for various cracking

patterns, deck spalling, joint spalling & other signs of distress. Steel structural

components warrant inspection for corrosion, stress cracks, buckles & distress. Timber

structural components should be inspected for structural decay caused by insects, fungus,

chemical attack, etc. Stone & masonry components warrant inspection for damage due to

weathering, spalling & abrasion due to wind etc. Based on the above procedures,

inspection ratings are prepared for each individual member & is known as “Estimated age

of the member”. This inspection will give greater value in maintenance, repair & if

replacement is needed for the future.

INSPECTION GUIDANCE: The bridge engineer & inspector should be familiar with terminologies included in

bridges & should be well versed in the tools & devices used in bridges. He must have a

thorough knowledge of safety precautions & should be properly organize, prepare the

necessary documents for the inspection purposes. He shall have good knowledge in

judging the construction materials which have used in the construction of bridges such as

concrete, steel, timber etc. In addition to it he shall have knowledge in foundations on

which the bridge piers will rest.

DETERIORATION IN CONCRETE:1. Freezing & Thawing:

Porous concrete absorbs water & creates high expansive pressures which results in

cracking, scaling & spalling of concrete.

2. Salt Action:

The use of salt contribute to weathering through recrystallization & it also

increases the chemical attack on concrete & steel.

3. Unsound Aggregates:

These are structurally weak & readily cleavable.

4. Leaching:

Water seeping through cracks & voids in the hardened concrete leaches or

dissolves the Ca(OH)2. It results in efflorescence encrustation at the surface of the

cracks with evidence of CaCO3.

5. Chemical Attack:

A number of chemicals attack concrete.

6. Wear or Abrasion:

Traffic abrasion & impact cause wearing of bridge decks & kerbs, parapets, piers

gets damaged by the scraping action of vehicles.

7. Foundation Movements:

These movements can cause serious cracking in structures.

8. Shrinkage & Flexure forces:

Shrinkage & flexure forces set up tensile stresses causing serious cracks.

9. Rusted reinforcing steel:

Corrosion of steel causes increase in its volume & exherts radial expansive

pressure on concrete, leading to cracking & for further rusting.

The following figure shows the cracks in the Columns, beams & slabs. This building is a Subway station in New York city.DETERIORATION IN STEEL:

1. Air & Moisture:

This will cause corrosion of steel, especially in a marine environment.

2. Industrial Fumes:

This fumes mainly cause deterioration of steel.

3. De-icing Agents:

Under damp conditions, it will attack steel causing corrosion.

4. Sea-water & Mud:

Unprotected steel piles if immersed in sea water & embedded in mud results in

serious deterioration.

5. Thermal strains or Overloads:

Where movement is restrained, the steel may yield, buckles.

6. Fire:

Extreme heat will cause serious deformation of steel members & loss of strength.

7. Collisions:

The vehicles may strike the steel beams, columns causing damage to the bridge.

8. Animal Wastes:

This will results in rusting of steel items.

9. Galvonic action:

Other metals which remain in contact with steel may cause corrosion.

During inspection, the inspector should note down the location, characteristics, &

the extent of rusted areas. The size & depth of the pitting should be measured.

In the case of cracks, the crack will vary from hairline thickness to the sufficient

width & these cracks will be serious one. The inspector should locate the location of the

crack, length of all cracks.

In the case of buckles & kinks, the inspector should note down the members

damaged, the type of the member, location etc.

In the case of stress concentrations, observe the paint around the connections of

large strains due to stress concentrations & should be alert in case of sheared bolts &

rivets.

FOUNDATION MOVEMENTS: These movements are caused by the movement of the supporting strata. In this

case the soil deformations are caused by volume changes & settlement or subsidence in

the soil or by a shear failure. The movements can be classified into four types. They are

1. Lateral Movements:

Earth retaining structures such as abutments, retaining walls, piers will undergo

this type of movement.

2. Vertical Movements:

Any type of structure which was not founded on a solid rock may undergo this

type of movement.

3. Pile Settelements:

Piled foundations will undergo this type of movements.

4. Rotational Movements:

This movement will cause unsymmetrical settlements or lateral movements or

steep cut slopes.

CHECKED DURING INSPECTION: First the movement is checked by looking the deviations from the proper geometry

of the bridge. Members & lines of the bridges should be either parallel or perpendicular

to each other. The inspector should check the following points while inspecting the

bridge

1. Checking the alignment:

Any abrupt change in the alignment of the bridge indicates a movement of the pier

or bearings.

2. Sight along railings:

A sudden dip in the rail line is indicating the result of displacement of a pier or

abutment.

3. Run profile levels:

This inspection will not only help us to establish the existence of any settlement,

but will also identity any differential settlements across the roadway.

4. Check piers, pile bents, abutment faces:

This inspection is employed to check the plumbness. An out of plumb pier in

either direction usually signifies foundation movement & it also indicates a

superstructure displacement.

5. Observing expansion joints:

This should be checked for the signs of opening or rotating. It will indicate the

movement of subsurface soils which results in abnormally small or large openings,

differential elevation etc.

6. Observe slabs, walls & members:

The cracks, buckling, & other deteriorations should be noted.

7. Checking back walls & Beam ends:

Back walls should be checked for cracking developed by the abutment rotation,

sliding or pavement thrust. This is a sign of horizontal movement of the abutment.

8. Unbalanced post-construction embankment or fill:

Embankments should be checked for balance & positioning. Unbalanced

embankments may cause a variety of soil movements which may impair the structural

integrity

UNDER WATER INVESTIGATIONS: This investigation has to be performed by the personnel experienced in these types

of inspections. However, the bridge inspector is responsible for the bridge inspection &

for the evaluation of the underwater portions of the bridge. Relatively new structures

have collapsed due to the corrosion of the steel piles below the concrete protection. PSC

piles will not fail below water level, while timber piles are known to be vulnerable. This

type of investigations is very important in the case of constructions to be done in the sea.

During inspection the following points may be checked.

1. Pile bents:

Piles made up of all materials should be checked below the water lime for any

signs of damage. Further the piles may classified into three groups namely

a) Steel piles: These are susceptible to corrosion all over & are severely attacked by

the chlorides. In the tidal zone, the piles which are concrete – jacketed should be

carefully checked for corrosion.

b) Timber piles: These should be observed carefully from the highest water level to

the mud line for marine borer & shipworm attacks on timber pilings.

c) Concrete piles: These should be checked for cracking particularly in case of

hollow prestressed piles & spalling due to rust form chloride attack on

reinforcement.

2. Dolphins & fenders:

These should be inspect below the highest water for deterioration & borer attack,

& any damages caused by vessels or large floating objects.

3. Pier & Abutment Conditions: This should be examined for any deterioration of the concrete or of the rubble

masonry & for any indication of pier movements & abutment movements.

4. Scour:

The river bottom around the piers & abutments should be checked for

development of scour holes, unintended exposure of piling, & the condition & effect of

any scour-control-installations.

The following items should be inspected properly.

of the bridge.

Approaches:

Approach pavement is to be checked for the unevenness, settlement or roughness.

Existence of defects may cause vehicles coming onto the bridge to induce undesirable

impact stresses in the structure. Cracking in slab indicates a void under the slab from fill

settlement. The joints between approach pavement & the abutment backwall is to be

examined to determine if there is adequate clearance. The condition of the shoulders,

slopes, drainage & approach guard rail should also be checked.

WORK PROTECTION: The following points are necessary for inspection & maintenance of protective

works:

1 During flood season, careful patrolling & watching is necessary that too in first

flood to detect any weaken in construction & take the necessary action.

2 The engineer should have the records of previous protective work & the behavior

of the river. This will help in the solving the practical problems.

3 A reserve quantity of stone can be used in the emergency situations. 2% of the

total quantity of boulders used in apron & slope pitching may be kept as a reserve

in stock for the emergency use.

4 Any small rain cuts or displacement by waves along the guide bund or approach

bank must be repaired immediately otherwise there will be chances of major

disaster.

5 Settlement in the bank or bridge or slip in the slope should be repaired

immediately.

6 Soundings should be taken near the guide bund when the river is in flood.

INVESTIGATIONS OF STRUCTURAL COMPONENTS:1. Note down any structural cracks more than 0.3mm in width & any signs of

deterioration & distress. In a structure this will range from usual surface cracks to

serious structural cracks & manifestation of distress zones.

2. If the observed manifestations of distress in the structure are so serious, then it

will require the detailed structural investigation in order to enable to decide

between repair & part or complete demolition & replacement. A detailed

explanation supporting reasons & the details of the likely causes that obviously

lead to such distress is given.

FUNCTION OF BRIDGE MAINTENANCE: An important function of bridge maintenance is to maintain a complete, accurate

& current record of each bridge on the highway system. Records should provide a full

history of the structure including all recommendations for strengthening & repair along

with the actions which have been taken on these recommendations.

The records shall contain the general description, history, dimensions & condition

of the structure. The information contained in reports is obtained from field

investigations, supplemented by reference to ‘as-built’ or ‘field checked’ plans. A report

should be made for each bridge investigation, even though it may only be cursory

inspection. At least two photographs of each bridge, one showing a roadway view & one

a side elevation view, should be included as part of the original bridge report. Other

photos necessary to show major defects, or other important special features, may also be

included. Necessary stress calculations to determine the safe load limit based on field

measurements or checked plans should be available for quick & easy reference.

CHECK LISTS: For the effective maintenance of bridges the following lists have to be properly

maintained.

1. General

2. Original bridge reports

1 Bridge number

2 Date of investigations

3 Name

4 Location

5 Description

6 Skew

7 Spans

8 Total length

9 Roadway width

10 Surfacing

11 Sidewalks

12 Railing

13 Alignment

14 Traffic lanes

15 Design live loading

16 Warerway

17 Other features crossed

18 Clearances

19 Date built

20 Plans

21 Plans & dimensions

22 Condition of structures

23 Restrictions

24 Miscellaneous

25 Stress analysis

26 Recommendations

27 Signature

28 Channel profile

29 Encroachments

30 Environmental conditions

31 Average daily traffic

3. Revised original bridge report

4. Supplementary bridge report

Bridge number

Date

Bridge name & location

Work done

Revised dimensions

Condition of structure

Restrictions

Revised stress analysis

Recommendations

Signature

CONCLUSIONS: A bridge serves its purpose only it is maintained properly. For this purpose, the

bridges should be checked once in a month. In the inspection if small cracks or any other

defects are found then, it should be rectified without negligence & if some major defects

are found then necessary steps are taken to demolish the bridge & rebuilding of the

bridge or replacing the bridge component. It is important to maintain the records of the

bridges with various photographs of the bridges, plans, design of the bridge components

detailed drawings etc & it can become useful in emergency situations.

REFERENCES:[1] Kenneth.R.White, John minor, Kenneth.N.Derncher, Courad.P.Heins.Jr “Bridge

Maintenance & evaluation”, First edition, published by Marcel Dekker Inc, 1981.

[2] S.Ponnuswamy “Bridge Engineering”, Second edition, published by Tata Mc Graw

Hill publishing, 1986.

[3] V.K.Raina “Concrete Bridge Practice”, First edition, published by Tata Mc Graw Hill

publishing, 1988.

[4] V.K.Raina “Concrete Bridges”, Indian edition, by Tata Mc Graw Hill

publishing, 1994.