Career Profile of

Career Profile of
Er. V.K. Raina
Technical Advisor to Govt. of Bahrain
Recipient of S.B. Joshi Memorial Award for Excellence in Bridge & Structural
Engineering for the year 2010, cited by Alumni Association of College of
Engineering, Pune
Date of Birth:
• 25th Nov, 1940
Educational Qualification and Training:
• Ph.D (Civil Engg), London University (Imperial College), England in 1966
• D.I.C. Masters Degree in Concrete Structures & Technology, Imperial
College, England in 1964.
• B.Sc (Civil & Municipal Engineering), Banaras University, India
• Training in tall buildings and bridges at Battersea College Technology,
London, UK
• Training in Soil Mechanics and Structural Analysis at City University,
London, UK
• Training in Construction Management and Contract Management at Regent
St. Polytechnic, London, UK.
Professional Experience and Training:
• Consulting engineering practice for ten years in various fields of Civil
Engineering covering bridges, industrial structures, buildings, aircraft
hangars, chimneys, cooling towers, water tanks, silos, etc.
• Designed and supervised construction of over 10000 lane-meters of concrete
bridges in different countries on various types of foundations in different
substrata conditions.
• 16 years experience as a Senior Expert and Consultant to the United Nations
and to World Bank.
•
24 years practicing professional experience with international consulting
engineers in the private sector in developed as well as developing countries.
•
Operation Advisor in bridge engineering, contract management, training in
design, construction, supervision and business development in various 17
countries as an independent consultant.
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•
•
UN expert and team leader of UN team of experts.
Training imparted to senior engineers in various countries on concrete,
bridges and flyovers, construction management, highway projects, contract
management, maintenance and rehabilitation.
Publications:
• Authored 8 practical reference-class books in civil engineering
• Numerous technical papers and technical advisories and operational
procedures in national and international journals, conferences, seminars and
other fora.
Honors & Awards:
• Two Gold Medals for merit at Engineering Graduation by Banaras Hindu
University.
Commonwealth Scholar, London University, London, UK
Cited in the “Who is Who”, India
Citation’ for various Professional Papers
Affiliation with Professional Bodies:
•
•
•
•
•
Member of ICE, London, UK.
Chartered Engineer (C. Eng), London, UK
Member of IRC, New Delhi, India.
Professional Engineer (P. Eng), Ontario, Canada.
Member of various professional Civil Engineering committees for drafting
of Codes of Practice for design, construction and specifications.
• Member of committees for management of works, reviewing of technical
books & papers, monitoring of research projects, recruitment of engineers,
etc.
Details of Contact:
Dr. V.K. Raina,
Techl. Advisor to Govt.of Bahrain: Bahrain Qatar Causeway
Flat 26, Building 1110, Road 3223, Mahooz,
Manama 332, Bahrain (Middle East)
Ph: + 973-39188863, Work : +973-17545807 / 748 09818576767
Email: [email protected], [email protected]
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16 A SHORT HISTORY OF DEVELOPMENT OF
‘BRIDGES’
Dr. V. K. Raina
Technical Director: ITNL (IL&FS)
Member: International Panel of Experts ….Bridges –
World Bank / DFCCIL
16.1 Introduction
Bridge design and construction have come a long way during the past few centuries and
‘much water has flown down’ particularly in the past hundred years or so during which
more bridges have been built than in ALL the previous centuries. The primitive bridge
building perhaps started with a trial and error process. In some misty morning of
prehistoric past, a human trying to cross a stream, probably saw a fallen tree across it.
When he tried to clamber over, it might have broken and dropped him in the drink. So he
thought really hard and felled a fatter tree and this took him across. The first primitive
single span wooden beam bridge was thus conceived, designed and built that day! The
first arch bridge might have similarly been built about four thousand years back in the
Euphrates valley in the Middle East!
The man who creates technology i.e. the engineer, with the aid of the scientist, is the
society’s most radical revolutionary. He is the fundamental agent of all social change.
Over the past 125 years the understanding of structural behavior unfolded cascading!
Tools for structural-analysis sharpened, strength of materials began to be understood
better, and ‘lo & behold’. The Art and Science of structure-design took roots.
Meanwhile better construction materials developed and advanced from stone to timber to
brick to wrought iron to cast iron to mild steel to reinforced concrete to high strength
steel to composite construction to prestressed concrete and accordingly, spans began to
become longer and bolder as we progressed into higher strength steel, high tension steel
& high strength concrete.
The flexural strength of a section was proportional to the cube of its depth and only
linearly to it’s ‘width’, was perhaps the greatest revelation in understanding structure
efficiency! The same 3 cm x 25 cm Plank of ‘good’ timber could withstand 6 times the load
if its 25 cm dimension was held vertical instead of the 3 cm dimension was Eureka in
philosophysing the efficiency of the structural-design. profs. argyris / henderson
/zienkiewitzch / makowski et al and we got the all powerful tools of the flexibility method
and the stiffness method for structural analysis and suddenly the unthinkable happened, the
“Aircraft” wing structure (thousands of times indeterminate) could readily be analyzed for
the first time ever !
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To trace this glorious history of bridges from the beginning, we should perhaps divide it into
two periods, as it is customary to talk about history in terms of periods. The first period
would be ‘before concrete’ ie the stone to steel ages, and the second, in which we are living
‘after concrete’. Stone and timber were the traditional building materials since the start of
civilization.
16.2 Arch Bridges
Stone arches used mostly in ‘early bridges’ date back to the days of Babylon. Romans
learned the art of building arches from the Ettruscans. These arches were semicircular. Flat
arcular arches appeared in full glory during the renaissance period.
Although the first theory of arches came to be established as late as 1695 and was used in
practical design only in 1729, the optimum profile of the stone arch had been found very
early by artist-builders intuitively and has changed very little since.
Some of the developments in arch bridges are illustrated as follows:
• Sequence of arches with wide piers look better than narrow ones as shown in Fig.16.1A
&
16.1B.
Very flat and wide spanned arches are possible on good ground as shown in Fig.16.2.
• Series of arches on tall piers are good for construction of viaducts as shown in Fig.16.3.
• Sequence of arches, wide piers look better than narrow one as sown in Fig.16.4.
• Fig.16.5 shows Flat arches deck and arch join in crown.
• Sequence of flat two-hinged arches is shown in Fig.16.6.
Fig.16.1A & 16.1B Sequence of arches
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Fig.16.2 Very flat and wide spanned arches
Fig.16.3 Series of arches on tall piers (viaduct)
Fig. 16.4 High arches open spandrel above arch crown
Fig.16.5 At flat arches deck and arch join in crown
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Fig.16.6 Sequence of flat two-hinged arches
Back in 1502, the great Master Leonardo Da Vinci produced a master sketch for a 240 m stone
structure intended to span the Golden Horn, an inlet between Istanbul and Pera. But then 500
years ago, when the sketch was made, the available technology was incapable of realizing such
an ambitious structure, and in consequence, Sultan Bejazet II feared committing himself to the
project. This sketch was lost for the next 450 years and then, luckily, was discovered by Vebjorn
Sand – a Norwegian artist in an exhibition of Leonardo’s documents in the late 1950s!
Vebjorn built this wooden foot-bridge in Norway based on the great Master’s sketch. Da Vinci’s
celebrated sketch has fascinated architects and engineers ever since it was discovered 50 years
ago. It is simply a pearl of perfection. Vebjorn’s flyover was unveiled in October 2001. It spans
the E-18 Highway between Oslo and Sweden in the town of ‘As’. The Norwegian artist has been
the driving force behind the project since 1995 and he now wants to build a version of this bridge
on every continent. Vebjorn has worked with Architect Kunet Selberg for this bridge in Norway,
which is 100 M long, built of timber by the specialist Moulven Group.
16.3 Steel Bridges
While stone and timber remained the common building materials for bridges, the mid-nineteenth
century demanded stronger and bigger bridges over large rivers for railways. So around 1840 the
transition from timber to steel began .In this period cast iron (and later wrought iron) was tried
out by bridge builders.
The first recorded use of iron in bridges was a chain bridge built in 1734 by the German army
across the Odor River in Prussia. However, cast iron was not found very suitable for building
large span bridges, because of low tensile strength of cast iron. A combination of cast iron for
compression members and wrought iron for tension members was used in truss bridges from
1840 onwards, especially for railway bridges. In 1856, Bessemer patented a process for making
large quantities of steel economically. In 1861 Siemens and Martin introduced the open hearth
process. In the last part of the 19th century the new material ‘steel’ caught the imagination of
bridge builders.
The Firth of Forth cantilever bridge of 520m span or Brooklyn bridge, Roebling’s suspension
bridge of 490m span, were a few of the famous achievements of the 19th century to mark the
beginning of modern era of bridge engineering in steel. By the turn of the 19th century, the
growing use and availability of structural steel and greater skills in analysis, design and
construction methods paved the way for longer span bridges.
Multiple span girder bridges, arch bridges and cantilever bridges in steel reached very long spans
with comparative ease. Howrah Bridge (1943), a steel cantilever bridge with a total length of 457
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m, is a typical example of the large crop of outstanding bridges built in steel in the earlier years
of the last century.
16.3.1 Suspension Bridges
A very substantial advance in the understanding of theoretical analysis of the load response of
the structural system of suspension bridges was made by the twenties of the last century and
many elegant bridges were built, like Lin-dern-thal’s Manhattan bridge (1909) with 450m span,
followed by Steinman’s 340m span Flo-riano-polis bridge and the Delaware river bridge of
530m span in 1926, to name a few at random.
The big leap forward came in 1931 with the construction of George Washington bridge, which
has been acclaimed by no less than Stussi as “ a great and the most important step in the
evolution of the ART and CULTURE of bridge engineering”. Le Corbusier was enchanted with
this bridge and in his 1937 publication “When Cathedrals Were White” quipped: “The George
Washington Bridge is the most beautiful bridge in the world... It is blessed …. the seat of grace.”
The bridge broke the 1000m span barrier and its span length of 1060m was double that of
Delaware Bridge, the then longest span in the world.
This also proved (by the successful construction of an eight-lane major roadway without
stiffening girders) an important fact that was already sensed by the great French analyst Navier
and intuitively made use of by the great US master builder, Roebling. The bridge was built by
Amman, a Swiss engineer who had migrated to America in 1904. Three decades later, this
‘foremost bridge builder in the world’, contributed his last great masterpiece to the land of his
adoption…VERAZONA NARROWS ! Amman’s Verrazano Narrows Bridge in New York was
opened in 1964, ten months before he died. Standing with a main span of 1300m, the bridge is a
landmark in the history of long span suspension bridge building.
The lessons in ensuring aerodynamic stability were learnt in a hard way by the tragedy of the
855m Tacoma Narrows Bridge which fluttered and perished in 1940 in a 64 km/h wind. Collapse
of Tacoma Bridge. The plate-type stiffening girders oscillated under high wind out in the open,
resonance reached very large amplitudes and the ‘Galloping Gertie’ collapsed with one side
rising 28 ft. above the other. 10 to 12 m deep wind–stiffening trusses were introduced next, but
these spoilt the beauty.
Prof. Leonhardt’s idea was to prevent the creation of wind forces which cause the dangerous
oscillations, and not to counteract them by additional stiffness of big truss box girders which
even increase wind loads. This can be realized by aerodynamic shaping of the bridge deck so that
the wind stream hitting it broad-side on cannot form eddies. Simultaneously the reaction forces
caused by the wind (static wind loads) can be reduced considerably. The dangerous torsion
element of the oscillation can further be prevented by suspending the deck from one cable only.
The mono-cable suspension bridge was created along these conceptual lines. Fig.16.7 shows the
first design for such a completely new type of suspension bridge deck was made in 1960 for the
Tagus Bridge in Lisbon and tendered for by a consortium of European construction firms. The
1104 m span bridge was, however, built the usual way, using Stiffening Trusses, the old mind-set
problem. The aerofoil deck system of Severn Bridge is shown in Fig.16.8.
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Fig.16.7 Mono-cable Suspension Bridge
Fig.16.8 Severn Bridge and aerofoil deck-section.
16.3.2 Introspection of Failures of Steel Bridges
The Hyatt Regency hotel walkway collapse was a major disaster that occurred on July 17, 1981
in Kansas City, Missouri, killing 114 people and injuring more than 200 others during a tea
dance. Based on many a Bridge DISASTER, Where there is lateral interference, particularly
from ‘certain’ critical sides, and readiness to hide ignorance and incompetence, there is always a
way out! All it takes is: “constitute a “COMMITTEE of the like-minded” and procedurally kill
the matter. A competent engineering analysis from purely pathological point of view and an
uninhibited autopsy of the accident are the only ways to help the understanding rise from the
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ashes of disaster. Thus the failure of Tacoma did not condemn suspension bridges. Instead,
simple aerodynamic stability measures found to beat the bridge flutter problem have paved the
way for bigger and more elegant suspension structures.
King’s bridge failure due to brittle fracture did not mean that welding of steel box girders was
banned. It only underlined the need for the right welding technique to be made available at most
bridges. The series of box girder failures of the 1970s could not lead to the conclusion that there
was anything fundamentally wrong with the thin plated structures. The second order analysis of
‘instability of thin plates’ due to geometric imperfections only earned the design attention that
was previously lacking!
Few, if any of the failures, became inevitable merely through the inexactitude of available
methods of computing stresses. It would be an illusion to suppose that greater perfection in such
methods and a bigger pile of computer printouts, ‘of itself’, will reduce the risk of accident.
Sound design is achieved above all by the wisdom and judgment with which the designer applies
his results, not by mere computations! Great courage and judgment are demanded of the
enquirer, as he has a task which requires freedom from bias while at the same time demanding a
definite opinion. It is re-assuring to remember that an Optimist is one who has met too many
Pessimists! Originality comes out of Understanding, and Understanding comes out of relentless
Practice, NOT from mere information. Good Judgment comes out of Experience and Experience
often comes out of bad Judgment.
16.4 Cable Stayed Bridges
In 1820, Navier in opting for the classical suspension system condemned the cable stayed
solution as unsuitable! It remained so until in 1938. Dischinger developed a suspension system
which was actually a combination of cable stayed and classical suspension bridge types.
Prof. Leonhardt hypothecated in his 1972 IABSE Paper that for spans of 750m to 1500m the
cable stayed system was technically and economically superior to the classical suspension bridge
especially with regard to aerodynamic stability.
With respect to the number and configuration of cables and pylons, some of the developments in
cable stayed bridges are illustrated as follows:
1. The number of cables in fan shape supported by two pylons are shown in Fig.16.9A, 16.9B
and 16.9C. The more the cables, the thinner is the beam.
2. The number of cables in harp shape is shown in Fig.16.10.
3. Fig.16.11 shows the hybrid arrangement of cables in fan and harp. This is advantageous for
anchoring in pylon.
4. One side cable bridges are shown in Fig. 16.12A, 16.12B and 16.12C. The cables in fan and/or
harp shapes are anchored in one pylon.
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5. Fig.16.13 sows the use of A-form pylons with corresponding inclination of planes of cables,
fan shaped smaller diameter cables at closer spacing etc., and are the new trends in the design to
realize the large spans. Simple shapes pylons are shown in Fig.16.14.
6. High cable stresses to ensure favorable stiffness ratios and flat aerodynamically shaped
aerofoil beam sections with sharp wind noses are now the order of the day!
Fig.16.9A, 16.9B & 16.9C Number of cables in fan shape.
Fig.16.10 Cables in harp shape.
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Fig.16.11 Hybrid Arrangement of cables between fan and harp shapes
Fig.16.12A, 16.12B & 16.12C One side cable stayed bridges.
Fig.16.13 Simple shapes of PYLONS for Cable Stayed Bridges
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Fig.16.14 Shapes of PYLONS for central suspension
The great Timoshenko, in his ‘History of Strength of Materials’, points out: “The construction
of the first railroads greatly affected the development of Strength of Materials by presenting a
series of new problems in the Art of PURE ANALYSIS especially in bridge engineering which
had to be solved”.
The great Stussi remarked in the IABSE Symposium on ‘Concepts of Safety of Structures’
(London, 1969) that the scientific period of design “was introduced by Louis Navier (17851836) who provided the transition to scientifically based construction with his principal
work: “Resume des Lecons” (1826) and thereby fundamentally created the applied science
of Statics”.
Navier gave these lessons on ‘the application of mechanics in the establishment of
construction and of machines’ in the Royal School of Bridges and Roads (L’Ecole Royale du
Ponts et Chaus-sees), Paris, and some of his students were to emerge as eminent groundbreaking engineers in future years.
16.5 Concrete Bridges
After Navier, the development of engineering design was fostered by very many pioneers
like Carl Culmann, Otto Mohr, and Friedrich Engesser, to name only a few of the giants.
And the glorious history of Roman concrete, used to build such famous structures as the
Pantheon, is more well-known.
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Animal blood was used in their earlier days for mixing ‘concrete’ History of civil engg. is
rather fascinating – if not intriguing.
But the art almost went into oblivion until its grand revival in the recent times marked by the
entry of portland cement into the scene.
With the progress of portland cement concrete, it came to be used in bridges as substitute for
stone. Concrete was first used for a bridge of l3.5m span across a canal in France in 1840.
The Frenchman Lambot’s famous rowboat 3.30m long ‘made by plastering Roque-fort
cement on a skeleton network of iron and wire’ was followed by his English patent in 1855.
Coigent, another Frenchman, took out a patent at about the same time on the structural use of
reinforced concrete. In 1855, Wilkinson secured in England a patent for a “concrete ARCHfloor” reinforced with tie bars, which had been discussed by Fairbim in his celebrated book
(1864). Moiner’s first patent was taken three years later.
Many others about this time took patents on reinforced concrete in one form or other, in
various lands.
Thus in the nineteenth century, reinforced concrete was still in the empirical period of
patents!
The search for a basis of rational concrete ‘structure-design’ began in the last part of the
nineteenth century itself.
Thadd-eus Hyatt is credited to be the first to establish the basis of Analysis of Stress in
Reinforced Concrete by stating ‘the principle of BOND’ and that ‘the reinforcement must be
able to resist sufficient tensile stresses to ‘balance’ the compressive stresses in concrete’.
Hyatt was an American lawyer by education but inventor by nature and was later to take
patents on deformed bars. He published his 28-page book on ‘the use of portland cement
concrete combined with iron’ in 1877 which may have ante-dated the design principles to
emerge by good two decades.
Koennen, a German master-mind, a government architect in Berlin, was commissioned to
‘DEDUCE’ the methods of computation of reinforced concrete sections and he published his
‘design rules’ in 1886.Coignet’s ideas on elastic design were printed two years later.
Inelastic theories of design, which were to be rejected rather irrationally later, also appeared
in 1898.In 1909, the joint code of ACI, ASCE, and other professional societies of America,
interested in reinforced concrete, made its grand entry. The French Commission on
Reinforced Concrete had formulated its DESIGN RULES back in 1906. Here is an
example!!! quoted from the 1904 proceedings of Institution of Civil Engineers, London
(extract of a Paper from La Genie Civil, Paris) about a bridge just constructed, spanning the
river Aisne at Soissons ‘made throughout in reinforced concrete, costing £ 7,700’: “For a
similar bridge in masonry, £ 1,875 would have to be added (to the cost figure), while if the
bridge were in steel, an extra cost of £ 1,460 would be entailed.” These were very telling
figures to guide one’s options. But direct saving in construction cost was not all that
mattered.
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Visionary: Abrams, giving his well-known correlation of ‘water-cement ratio with concrete
strength’, wrote in 1919: ‘use the smallest quantity of mixing water that will produce a
plastic or workable concrete’, what a visionary pronouncement back then! With careful
control of water and proportioning, attention was focused on ‘Workability, Placing, and
Compaction’. The wonderful M. Freyssinet proposed ‘compaction by VIBRATION’ way
back in 1917! Alongside came the improvement in composition and in the fineness of
grinding of cement and the strength of concrete actually increased, what a turning point
again! In Europe, they used m.s. plain; Americans preferred it deformed! The designers had
chained themselves universally to a low permissible stress of 125 MPa and the bogey of
cracking and corrosion made higher strength reinforcement almost a taboo!
16.5.1 Prestressed Concrete Bridges
The big break in the art of reinforcing the concrete came with the introduction of
‘PRESTRESSING’. The idea of prestressing, conceived and put to practice in the 20th
century, is the single biggest happening of greatest significance in the entire History of
Construction on this planet .
The man who first gave the form and content to this concept, the originator of prestressed
concrete, was none other than the builder-geneous of our time M. Eugene Freyssinet,
perhaps the greatest civil- engineering visionary of all times. A lesser man would have
been content with the fame and fortune he had in the 1930s. But Freyssinet was a man with a
mission in his heart. His life carries an obvious message . His bitter struggles for seven long
years for the cause of prestressed concrete made history. If history has to have its heroes,here
was one for the History of Bridges!
M. Freyssinet took patents in 1928. He was out to sell the history’s most exciting building
material, but alas, with no buyers around He had reportedly told his friend, M. Le Corbusier:
“I reached my goal. Now I am looking around to see what I can use this discovery for and
who will accept it. How Do I Convince Them? and in my opinion modern society needs it for
all their housing and their highways.” M. Le Corbusier was so touched by the sentiments of
his FRIEND as to conclude: “into that one short sentence he has crammed a vast wealth of
poetry, lyricism, solidarity, and concern for mankind and for the hearts of human beings”.
In 1960, beam bridges had already reached spans up to 160m, and Master Engineer
Morandi’s bridge across Lake Maracaibo in Venezuela was under construction with spans
of 235m already using stay cables ! In 1970, the longest span of beams reached 230m in
Japan, and for cable-stayed concrete bridges designs had been made with about 300m spans.
The achievements in building long-span bridges in prestressed concrete are too close to our
times to afford a historical perspective. The development of new landmarks in span, form,
and Construction-technology, is growing at a dizzy pace.
The originator of construction in ‘free’ cantilever box beam superstructures built without the
use of false work, which has revolutionized the building of prestressed concrete bridges, is
Prof. Ulrich Finsterwalder— one of the greatest bridge builders of our times.
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A later modification of this method is the cantilever construction with precast segments
introduced in the 1963 construction of Choisy-le-Roi bridge in Paris & the Ole’ron Bridge in
France by Enterprises Compenon-Bernard…. operating under the most famous Freyssinet –
Guyon school of Bridge culture and thought.
Urado Bay bridge in Japan is a 270m span cantilever type bridge. Use of lightweight
aggregates in future may increase the span range of these elegant bridge types further.
So, in brief, the present development of prestressed concrete proved to the hilt that
Freyssinet’s seven years of ordeal did not go in vain.
Engineering has come a long way since --- at least in some ways Precasting techniques,
using spine segments and even placing Bearings at bottom of pier (to cut out majority of
moments in foundations) for instance. Precasting techniques used in Prestressed Concrete
bridges,are illustrated as follows:
1. An early example of placing bearings at bottom of pier, is the 700 m PSC Hammersmith
flyover in London, as shown in Fig.16.15.
2. The excellent example of spine segments, is the 1000 m long PSC Mancunian Way
Flyover in Manchester, as shown in Fig.16.16. The Fig.16.17 shows the cross section of the
flyover and the Fig.16.18 shows the section through the 2-lane and ramp structures.
3. Another very good example of Precast segmental PSC construction, is the 2.1 Km long AlKhaleej Viaduct in Riyadh, Saudi Arabia.
4. For a 3-lane precast unit,the arrangement of prestressing cables is shown in Fig.16.19 and
the cross section is shown in Fig.16.20.
Fig.16.15 PSC Hammersmith Flyover in London
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Fig.16.16 Spine Segments - the 1000 m long psc Mancunian Way Flyover in
Manchester
Fig.16.17 Cross Section of Mancunian Way Flyover in Manchester
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Fig.16.18 Section Through 2 Lane and Ramp Structures
Fig.16.19A & 16.19B 3-Lane Precast Unit
16.5.2 Precast Segmental Construction
Flyovers have also been built totally using Precast elements. The stages of construction are
shown in Fig.16.20, 16.21, 16.22 & 16.23.
Precast abutments and wingwalls : The construction is illustrated in Fig.16.24. With respect to
Fig 16.24 following are the details of construction of precast abutment & wing walls
1. Concrete erection pads are cast in place to proper elevation and location.
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2. Deadmen footings are cast in place with steel dowel rods projecting from the deadmen to
facilitate welding of the braces.
3. Formwork for the cast-in-place footing is positioned.
Fig.16.20 Construction Stage 1
Fig.16.21 ConstructionStage2
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Fig.16.22 Construction Stage 3
Fig.16.23 Construction Stage 4
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Fig.16.24 Construction of Precast abutments and
wingwalls
1.
Concrete erection pads are
cast in place to proper
elevation and location.
2.
Deadmen footings are cast
in place with steel dowel
rods projecting from the
deadmen
to
facilitate
welding of the braces.
3.
Formwork for the cast-inplace footing is positioned.
4.
Precast abutment and
wingwall panels are set in
place by crane.
5.
Steel shims are used as
required to set the top
elevation of the abutment
and wingwalls.
6.
Erection
braces
are
attached to the deadmen
and panels after each piece
is erected.
7. After auxilliary horizontal
reinforcement is positioned
the footings are cast. When
the footing concrete has
attained strength, the
abutment acts as a
cantilever retaining wall
and is no longer dependent
on the tie back braces
Notes:
A. Abutments and wingwall panels are dapped 2 in. and the reinforcing bars protrude from
the panels into the footing.
B. Weld plates anchored into the panels provide for joining of adjacent panels and welding
of erection braces.
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C. Dowel sleeves, 3-in. diameter, provide for anchorage of the precast concrete bridge deck
members which offer additional strut support to the abutment walls.
D. Abutments and wingwall panels are dapped 2 in. and the reinforcing bars protrude from
the panels into the footing.
E. Weld plates anchored into the panels provide for joining of adjacent panels and welding
of erection braces.
Fig.16.25 Prestressed concrete sheet pile abutments and wingwalls.
1.
2.
3.
4.
5.
6.
7.
Prestressed concrete sheet pile abutments and wingwalls.
Prestressed concrete piling pier.
Reinforced concrete abutment and wingwall caps.
Precast or cast-in-place concrete pile cap.
Precast concrete curb unit.
Prestressed concrete deck unit
Precast concrete guard posts
16.6 Conclusion
Continuing efforts to expand scope and application of bridge engineering have led to
growingly imaginative forms of construction. It is an undeniable professional responsibility
on the part of a good bridge engineer to have the professional depth to know the culture
and the subtle turning points that tempered the bridge-craft as it developed and reflect
on them to carry forward its wonderful legacy!
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