Bridge rehabilitation covers many complex engineering problems and economic issues. It involves repairing, strengthening, or replacing existing bridges to improve their structural condition and functional capabilities. The main factors that can lead to bridge deterioration include inner bridge factors like design flaws; traffic load factors from increasing vehicle loads and speeds; weather and environmental factors such as pollution and temperature fluctuations; and inadequate maintenance. Bridge rehabilitation aims to address deterioration from these sources and extend the usable life of bridges.

1. BRIDGEBRIDGE
REHABILITATIONREHABILITATION
Bambang SupriyadiBambang Supriyadi
MPSP T.Sipil FT UGMMPSP T.Sipil FT UGM

2. Two main tasks for contemporaryTwo main tasks for contemporary
bridge engineeringbridge engineering
• to construct new bridge structures
according to the development of
transportation needs,
• to maintain the existing bridge stock
according to current and predicted
traffic and safety requirements.

3. The Term of MaintenanceThe Term of Maintenance
• is usually limited to the current works
performed systematically by maintenance
services to ensure normal and safe utilization
of bridge structures.
• These works consist mainly of inspection,
maintenance, repair and replacement, if
necessary, of expansion joints, bridge deck,
drainage system, railings and barriers,
pavement, bridge bearings, etc., as well as
anti-corrosive protection of some elements,
mostly by painting.

4. The termThe term maintenancemaintenance
may also be considered, more widely, as:
a multi-component process leading
to the fulfillment of all conditions
related to the safe utilization of
existing bridges in the anticipated
period of their future service.

5. Rapid deterioration of bridgeRapid deterioration of bridge
structuresstructures
• In the recent two decades, rapid deterioration of
bridge structures has become a serious
technical and economical problem in many
countries, including highly developed ones.
• It concerns also the concrete bridges, which for
many years have been considered as durable
and requiring minimum maintenance cost, while
only the steel structures demand anti- corrosive
protection being applied every few years

6. The reasons leading to deterioration of theThe reasons leading to deterioration of the
existing bridge stock (which have been inexisting bridge stock (which have been in
service 20-30 years or more)service 20-30 years or more)
• increase in traffic flows and weight of vehicles,
especially their axle loads, compared to the
period when the bridges have been designed
and constructed,
• harmful influence of environmental pollution,
especially atmospheric ones, on the
performance of structural materials,
• common use of de-icing agents in countries of
moderate climate,
continue

7. • low quality structural materials as well as
bridge equipment elements, such as
expansion joints, waterproofing
membranes, etc.,
• limited maintenance program or
insufficient standard of maintenance,
• structural and material solutions
particularly sensitive to damage
produced by both traffic loads and
environmental factors

8. Overloading or material fatigueOverloading or material fatigue
• deterioration of bridges, directly resulting
from overloading or material fatigue, is
relatively seldom observed till now, because
of safety margins in load-carrying capacity
and early remedial actions undertaken.
• The other above mentioned factors play
predominant roles in affecting deterioration
of bridges and leading to their structural
deficiency

9. AA structurallystructurally deficientdeficient bridgebridge
• is one whose components may have
deteriorated or been damaged, resulting in
restrictions on its use.
• Apart from the technical condition
problems, a great number of bridges built
many years ago are functionally obsolete.

10. FunctionalFunctional obsolescenceobsolescence
Functional obsolescence refers to a
bridge's load-carrying or geometrical
characteristics; e.g.:
• a bridge, which was designed 40 years
ago for lower load levels or traffic
volumes or with inadequate under- or
over-clearance and which now requires
restrictions on its use, is functionally
obsolete in spite of its good technical
condition

11. The following remedial actionsThe following remedial actions
can be undertakencan be undertaken
• repair,
• replacement,
• rehabilitation,
• strengthening,
• modernization

12. RepairRepair
• means to mend, to put into good
shape or working order again, to
recondition, to renovate, to restore
and to correct. Repair concerns
rather the local damages of
structural members or bridge
equipment elements than the
overall structure.

13. ReplacementReplacement
• means to substitute, to change and to
exchange.
• Some elements of bridge structures, mostly
equipment elements, are usually replaced, e.g.,
expansion joints, bearings, barriers, etc.
• Sometimes, the structural members are also
replaced, if necessary, e.g., deck elements,
individual stringers, secondary or bracing
elements, etc.
• Replacing a whole bridge is considered the last
resort in the process of upgrading the existing
infrastructure; it is a drastic measure and
possibly the costliest

14. RehabilitationRehabilitation
• means to restore, to make suitable, to put
back in good condition, to re-establish on
a firm, sound basis, to bring back to full
use, to reinstate, to renew and to revive.
• Rehabilitation concerns mostly the
whole bridge structure, including its
primary structural members.

15. StrengtheningStrengthening
• means to increase load-carrying
capacity by adding more material,
additional components
(e.g., external prestressing), and so on.

16. ModernizationModernization
• is a form of upgrading by adding new features,
e.g., new traffic flow arrangement, new signs,
new lighting, new barriers.
• This term is commonly applied to structures
designed and constructed prior to availability of
these modern features.
• However, modernization can also be considered
in a wider meaning. For instance, upgrading of
the bridge requires in many cases its
strengthening, new traffic flow arrangement
requires the widening of the bridge deck, and
so on

17. RetrofitRetrofit
• is a strengthening procedure applied
to an existing structure, not
necessarily although in many cases
related to seismic strength.
• It is applied usually after it is found
that the original design is not
sufficient in light of newly gained
experience

18. • All the above mentioned terms define various
actions concerning bridge works of different
scale and importance.
• However, it is very difficult to consider these
actions as fully separate ones. For instance,
rehabilitation of a bridge often requires its
adequate strengthening or replacement and
repair of some of its elements, etc.
• Therefore, repair, replacement, rehabilitation,
strengthening and modernization have usually
many relations to each other and they may be
considered to be the components of
maintenance in its wider meaning

19. "Bridge"Bridge Rehabilitation"Rehabilitation"
• its content also covers many technical and
economical problems related to other above
mentioned bridgeworks performed to improve
the technical condition and functional features
of the structures.
• Bridge rehabilitation covers many complex
engineering problems as well as economical
ones.
• Moreover, in the recent few years, many modern
rehabilitation methods and non-conventional
material solutions to improve the durability of
bridge structures have been developed

20. Focused on rehabilitation ofFocused on rehabilitation of
concrete bridgesconcrete bridges
• This is due to the fact that on the one hand they
represent a great majority of the bridge
population in many countries and on the other
hand, their rehabilitation is in general much
more complex than in the case of steel bridges.
• Moreover, maintenance works, e.g., anti-
corrosive coatings, are usually performed more
systematically on steel bridges. Therefore, their
technical condition is generally better than the
concrete ones.

21. Wooden and Stone bridgesWooden and Stone bridges
• Rehabilitation problems
concerning wooden and stone
bridges are neglected,
• because of their specific and
unique character related in many
cases to the historical merit of the
structures

22. Focused on highway bridgesFocused on highway bridges
• This is due to several reasons. Highway bridges
are much more numerous and therefore, their
rehabilitation needs are more evident than those
related to the railway bridges.
• Railway bridges, mostly built of steel, are generally
in a better position, as the intensity of rail traffic and
the increase of loads are less pronounced than in
the case of highway bridges.
• On the other hand, however, the problems
concerning rehabilitation of railway bridges are
specific due to the fact that they were often built at
the end of the XIXth century and at the beginning
of the XXth century and exceeded their design life

23. AA Practical GuidePractical Guide
• Some problems concerning bridge
rehabilitation in several countries are
formulated according to more or less
official guidelines, regulations and other
engineering requirements, e.g.:
• L. G. Silano (ed.). Bridge inspection and
Rehabilitation - A Practical Guide (John
Wiley & Sons, Inc., 1993), 288 pp

24. Factors acting on bridge duringFactors acting on bridge during
their servicetheir service
• Bridge structures are subjected to many
types of loadings and other influences
resulting both from the live loads (mostly
traffic effects) and exposure of the structures
to the weather and environmental effects of
various nature. The most important factors
acting on bridges during their service are
schematically shown in Fig. 3.1.

25. The most important factors acting onThe most important factors acting on
bridges during their servicebridges during their service

26. Deterioration and bridge damagesDeterioration and bridge damages
classificationsclassifications
• The classification relating to concrete bridges was
developed within the framework of Reunion
International des Laboratoires d'Essais et de
Recherches sur les Materiaux et les Construction
(RILEM 1991)
• The factors leading to bridge deterioration can be
classified into four fundamental groups:
(A) inner factors,
(B) traffic load factors,
(C) weather and environmental factors,
(D) maintenance factors

27. InnerInner factorsfactors
are immanently connected with the
structure itself. It means that the structure
may contain some factors of degradation or
causing special sensitivity to damage, e.g.:
• inadequacy of the design (including
structural system) and building,
• quality of the materials,
• the age, etc.

28. • The age of bridges is a very important factor.
In Europe, the life of the structural elements
is generally between 60 and 120 years and is
in accordance with many practical cases.
• On the other hand, however, a bad
adaptation of the design to the service
conditions or insufficient geometrical
parameters (e.g., too small clearance) may
endanger the good behavior of the structures

29. • It should also be pointed out that, in general, the
bridge structural systems with discontinuous
deflection line (e.g., the bridges of simple span
type) are more sensitive to damage from traffic load
than those with continuous deflection line (e.g., the
bridges of continuous span type).
• This is due to the dynamic effects (impacts)
produced by traffic load in the numerous expansion
joints representing structural discontinuity as shown
schematically in Fig. 3.2

30. Fig. 3.2. Structural system with (a) discontinuous and
(b) continuous deflection line

31. TrafficTraffic loadload factorsfactors
• are of external nature and are related to the exploitation
conditions.
• It should be emphasized that the intensity and speed of the
road traffic as well as the concentration of loads by the
heavy vehicles have enormously grown during the last few
decades and therefore, many old bridges are not adapted to
support, without damage, such an evolution, especially
because of the evident increase of dynamic effects.
• It should also be noticed that "if the static load per axle does
not grow, the axles are always nearer and so the load
becomes more concentrated, which is very
disadvantageous for certain elements of the bridges".
• The last remark, cited according to Ch. Van Begin, concerns
especially bridge deck elements.

32. • The exploitation conditions may also be changed
when the bridge is subjected to other types of live
loads than predicted in the design.
• For instance, the old railway bridges were designed
for operating under steam locomotive traffic and
when the railway traction was modernized from
steam to electric, many bridges, especially masonry
ones, are shown to be damaged due to the different
motion characteristics of electric locomotives (e.g.,
an evident growth of lateral dynamic effects)

33. WeatherWeather andand environmentalenvironmental factorsfactors
• are of climatic and atmospherically nature.
• Some of them (e.g., season and diurnal
temperature changes, rainfalls or wind pressure)
may be classified as objective ones, i.e., the factors
directly independent of human activity in the domain
of bridge engineering,
• while the others (e.g., atmospheric pollutions,
aggressive chemicals in underground water or in
rivers, effects of de-icing salts on structures) are
dependent on human activity in the bridge
engineering itself and in the other domains of
technical activity.

34. • It should also be emphasized that the bridges, in
contradistinction to many other structures (e.g., buildings of
various types), are generally not covered by roofs or other
protection elements and therefore, they are directly
subjected to weather and environmental effects.
• These effects are, in many cases, more important for bridge
durability than traffic load effects.
• Moreover, only certain factors are included in the design
calculations, such as temperature changes or wind
pressure, which usually belong to the standard design
parameters.
• Majority of the other weather and environmental factors are
not generally considered as design parameters and it is
either impossible or very difficult to predict their
development in time and harmful influence on the structures
(e.g., intensity of atmospheric pollutions or aggressive
chemicals in rivers)

35. MaintenanceMaintenance factorsfactors
• are entirely related to the quality and intensity of
preservation measures, such as anti-corrosive
protection, current conservation works, cleaning,
etc.
• Maintenance is, in many cases, a decisive factor
influencing bridge durability; inadequate routine
maintenance leads, in general, to bridge
degradation even if the structure is well constructed
with the use of structural materials and equipment
elements of high quality.
• Therefore, maintenance factors belong to those
depending on human activity in the bridge
engineering itself

36. ClassificationClassification
• Classification of factors leading to bridge
deterioration performed according to the
basic criteria denoted above by A, B, C, D
and I, II is presented in Table 3.1.

37. TableTable 3.13.1 Classification of factorsClassification of factors
leading to bridge deterioration.leading to bridge deterioration.
A. Inner factors; I. Objective
• A. I.1. The age of the bridge structure
A. Inner factors; II. Subjective
• A.II.1. Quality of the study
• A.II.2. Structural system itself--- sensitive to damage
• A.II.3. Adequacy of the design to the actual service
conditions (including geometrical parameters)
• A.II.4. Quality of the construction works at every stage
• A.II.5. Quality of the structural materials and bridge
equipment elements (e.g., insulation expansion joints,
drainage system elements, etc.)

38. B. Traffic load factors; II. Subjective (only)
• B.II.1. The frequency, speed and concentration of
traffic loads (especially the heavy vehicles)
• B.II.2. Dynamic effects (including fatigue damage
mostly in steel bridges)
• B.II.3. Car or other accidents on the bridge
• B.II.4. Overloading by the heavy vehicles
• B.II.5. Impacts produced by the oversized vehicles

39. C. Weather and environmental factors; I. Objective
• C.I.1. Atmospheric falls (e.g., rainfalls, snowfalls)
• C.I.2. Variation of the water level in the rivers, straits, gulfs, etc.
• C.I.3. Ice-float run-off and its pressure on bridge piers
• C.I.4. Wind pressure and its effects on structural and secondary bridge
elements
• C.I.5. The earth movements (including seismic effects)
• C.I.6. Diurnal and season variation of ambient temperature leading to the
uniform thermal deformation of the bridge structures
• C.I.7. Direct solar radiation on the bridge and other thermal effects
leading to the non uniform heat distribution in the bridge structures
• C.I.8. Chloride attack originating from the action of sea water
The factors denoted by C.I.1, to C.I.5. may be in some cases of a
catastrophic nature, e.g., flood, hurricane, earthquake, etc.

40. C. Weather and environmental factors; II. Subjective
• C.II.1. Chloride attack originating from the use of de-icing
products (mainly salts) on road under the bridge
• C.II.2. Frost destruction of concrete
• C.II.3. Atmospheric falls containing aggressive chemicals
(e.g., "acid rains")
• C.II.4. Penetration of CO; from atmosphere (carbonation
effect in concrete)
• C.II.5. Aggressive chemicals in rivers and underground
water
• C.II.6. Vagabond currents (e.g., in bridge structures over
the railroads with electric traction of direct current)
• C.II.7. Fire

41. D. Maintenance factors; II. Subjective (only)
• D.II.1. Structural, material and bridge equipment solutions easy or
difficult for maintenance works
• D.II.2. Quality of inspection of any type (e.g., cursory, detailed, special
inspections)
• D.II.3. Quality of routine maintenance works (e.g., cleaning, repair,
replacement of some elements of bridge equipment, etc.)
• D.II.4. Renewal of anti-corrosive protection of structural and other steel
elements
• D.II.5. The use of de-icing salts on the bridge roadway itself D.II.6.
Quality of the drainage system and its efficiency
• D.II.7. Quality of the pavement on roadway (e.g., roughness,
permeability, etc.) or railway (e.g., geometrical tolerance)
• D.II.8. State of pipelines of any types and other installations located on
the bridge

42. Bridge equipment elementsBridge equipment elements
• It should be emphasized that besides the quality of the
structural materials, the bridge equipment elements (i.e.,
industrial components such as bearing devices, insulation,
expansion joints, etc.) belong, in majority of the cases, to
the decisive factors influencing bridge durability.
• In general, damage of bridge structures has its origin in
permeable insulation of deck slabs, water infiltration through
expansion joints and ineffective drainage system.
• Therefore, the use of the above mentioned elements with a
high quality is technically and economically justified.
• In contemporary bridge engineering, the cost of all
equipment elements generally varies from 15-20% of the
total construction cost of the bridge, but in some cases, it
may reach even 30-40%

43. • For instance, permeable insulation layer of deck
slabs leads to water infiltration through concrete
and the leaks appear on the bottom faces of these
slabs and vertical faces of the girders.
• It should be noticed that rainwater is generally
alkaline and dissolves Ca(OH)2 crystals in cement
mortar, washing them out. It leads to a more porous
structure of concrete and is very often manifested
by the white efflorescences and even small
stalactites on the bottom surface of the deck slabs

44. Many other damages caused by the low quality of
bridge equipment elements or their inadequate
solutions can be listed, such as
• lack of outlets for water behind the abutments
causing leaks and washing out of Ca(OH)2 through
the walls,
• leaking expansion joints and lack of their adequate
dewatering,
• improper fixation of water outlets,
• corroded rainwater pipes,
• too short intermediate slabs between spans and
abutments, etc