LONG-SPAN BRIDGES (ENGM052)
RAFAEL SCUDELARI DE MACEDO (6399594)
COURSEWORK 1
*
23/02/2017
SUSPENSION & CABLE STAYED BRIDGES – BASIC
QUESTIONS AND RISK EVALUATION
This report presents the answers to the questions of coursework 1 of the
module long-span bridges (ENGM052) of the Surrey University’s masters
course in structural engineering. The term is the second semester of the
2016/17 lecture years.
Version
0.0
Author
Eng. Rafael Scudelari de Macedo
Date
23/02/2017
Comments
Submission for evaluation.
LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
COURSEWORK 1
S U S P E N S I O N & C A B L E S T AY E D B R I D G E S – B A S I C Q U E S T I O N S A N D R I S K
E VA L U AT I O N
SUMMARY
SUMMARY .......................................................................................................................................................... 2
1
INTRODUCTION .......................................................................................................................................... 3
2
ITEM 1: RISK ASSESSMENT ......................................................................................................................... 3
2.1
2.2
2.3
2.4
3
ITEM 2: CABLE STAYED BRIDGE .................................................................................................................. 9
3.1
3.2
4
DESCRIPTION OF TYPICAL ELEMENTS ................................................................................................................................... 9
500M SPAN BRIDGE ....................................................................................................................................................... 10
ITEM 3: SUSPENSION BRIDGE ................................................................................................................... 11
4.1
4.2
5
BACKGROUND STUDY ........................................................................................................................................................ 3
RISK ASSESSMENT TABLE..................................................................................................................................................... 5
MOST IMPORTANT LOAD CONSIDERATIONS ....................................................................................................................... 8
REMARKS ............................................................................................................................................................................ 8
DESCRIPTION OF TYPICAL ELEMENTS ................................................................................................................................ 11
500M SPAN BRIDGE ....................................................................................................................................................... 12
ITEM 4: MULTI SPAN ................................................................................................................................. 13
5.1
5.2
5.3
FOR BOTH CASES ............................................................................................................................................................. 13
CABLE STAYED BRIDGE .................................................................................................................................................... 13
SUSPENSION BRIDGE ....................................................................................................................................................... 13
6
ITEM 5: TABLE OF NOTABLE MULTI SPAN BRIDGES ................................................................................. 14
7
REFERENCES ............................................................................................................................................. 15
8
AUTHOR’S SIGNATURE............................................................................................................................. 16
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
2
LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
1 INTRODUCTION
The text of the coursework assignment [1], which was rendered available through SurreyLearn, contains 5
different questions. The questions are herein copied verbatim at the beginning of each section. The deadline for
the submittal date is the 28th of February of 2017 (at 4pm the latest).
The basic description of the assignment, which is valid for all questions, is:
CONSIDER A LONG SPAN BRIDGE CARRYING A FOOTWAY OVER A MAJOR
NAVIGABLE RIVER [1].
2 ITEM 1: RISK ASSESSMENT
Question Text: 1) Outline on the risk assessment table given below the main loads or actions that the bridge will need
to resist. Estimate the likelihood and severity of these loads and complete the REM (see next page) for these actions.
Which in your opinion are the 3 most important load considerations? [1]
2.1 BACKGROUND STUDY
For the development of this question, the student searched on the university’s library for papers containing
information on the causes of failure in bridges. From this research, the student encountered two relevant papers.
One of them, called State-of-the-Art Review on the Causes and Mechanisms of Bridge Collapse, had just been
published in ASCE’s Journal of performance of constructed facilities Volume 30 Issue 2 - April 2016 [2].
In this paper, the authors present the distribution of causes of bridge collapses in the USA as per a studied carried
out in 2003 by Wardhana and Hapipriono [3], in which the causes of 503 reported bridge collapses between
1989 and 2000 have been analyzed. This distribution is shown in Figure 1.
FIGURE 1: DISTRIBUTION OF DISTRIBUTION OF CAUSES OF THE 503 REPORTED BRIDGE COLLAPSES DURING THE PERIOD BETWEEN 1989 AND 2000 IN THE
UNITED STATES. DATA FROM [3], IMAGE FROM [2].
The original distribution from [3] is displayed in Table 1.
It is important to notice from the data that the flooding and scour alone account for almost half of the bridge
collapses.
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
TABLE 1: FAILUE CAUSES AND EVENTS. [3]
Failure causes and events
Hydraulic
Flood
Scour
Debris
Drift
Others
Collision
Auto/truck
Barge/ship/tanker
Train
Other
Overload
Deterioration
General
Steel deterioration
Steel-corrosion
Concrete-corrosion
Fire
Construction
Ice
Earthquake
Fatigue-steel
Design
Soil
Storm/hurricane/tsunami
Miscellaneous/other
Total
RAFAEL SCUDELARI DE MACEDO
Number of occurrences
266
165
78
16
2
5
59
14
10
3
32
44
43
22
14
6
1
16
13
10
17
5
3
3
2
22
503
6399594 – RS00742@SURREY.AC.UK
Percentage of total
52.880%
32.800%
15.510%
3.180%
0.400%
0.990%
11.730%
2.780%
1.990%
0.600%
6.360%
8.750%
8.550%
4.370%
2.780%
1.190%
0.200%
3.180%
2.580%
1.990%
3.380%
0.990%
0.600%
0.600%
0.400%
4.370%
100.000%
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
2.2 RISK ASSESSMENT TABLE
The historic bridge failure data, together with the student’s judgement, have yielded the following risk assessment
table. The student considered, for the likelihood of the events listed in [2] or in [3], that:




Percentage ≥ 10%: Frequent.
10% >Percentage ≥ 3%: Occasional.
3% > Percentage ≥ 1%: Remote.
1% > Percentage; or unlisted: Improbable.
The student used for the severity analysis this own judgement. This is due to the scarcity of information on how
frequently the occurrence of a hazard does actually translates itself as distress or collapse of the bridge (as
defined in [3]).
The classification of severity was largely influence by:


An estimation on how probable it is for a given event, when occurred, to cause the collapse or distress of
the bridge.
An estimation on of the predictability of the resulting forces that act on the structure from such an event.
Hazard, load
scenario
Likelihood
Severity
RIM
Flood/Tsunami
Frequent
Medium
U
Scour
Frequent
High
U
Collision –
Auto/Truck/Train
Occasional
Medium
T
RAFAEL SCUDELARI DE MACEDO
Comment
Effects:
 Direct drag forces on the columns and, if
the flood height is critical, act on the
bridge deck;
 May bring debris which hit the structure.
 May erode the riverbed and influence the
foundations.
Treatment:
 The bridge deck should be designed at a
safe height considering historical flooding
data.
 Estimate loads (water flow and debris
collision) on columns.
 Verify if a flood caused lasting effects on
the foundations and take correction actions
if necessary.
Effects:
 Lowering of riverbed due to water erosion,
leading to a reduction of the lateral
resistance of the soil supporting the
foundations.
Treatment:
 Design protection systems, such as a rocky
perimeter around the foundations, to
prevent scour.
Effects:
 High magnitude dynamic load that causes
a high stress concentrated on a given
structural member.
Treatment:
 Add protection systems, such as side rails,
to avoid collision of the vehicles with the
bridge’s vital structural members.
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LONG-SPAN BRIDGES (ENGM052)
Hazard, load
scenario
COURSEWORK 1
Likelihood
Severity
RIM
Collision –
Barge/ship/tanker
Remote
Severe
U
Overload
Occasional
Medium
U
Deterioration/Fatigue
Occasional
Medium
U
Fire
Occasional
High
U
RAFAEL SCUDELARI DE MACEDO
Comment
Effects:
 High magnitude dynamic load that causes
a high stress concentrated on a given
structural member.
Treatment:
 Add protection systems to the columns such
as a rocky perimeter around the
foundations, to avoid direct collision
against the columns.
 Increase the span of the bridge to avoid
being too close to the navigation channel.
 Avoid putting columns on water altogether.
 Instruct the water transit control about the
limitations of the bridge, such as limiting
ship height in accordance with water level.
Effects:
 Increase fatigue problems due to the
heavier loading of the deck.
 In extreme situations, cause failure of the
bridge’s structural members due to
overloading.
Treatment:
 Ensure that the road control personnel have
data on the limiting load of the bridges.
 In critical situations, add weighing devices
on both sides to ensure that carried load
does not exceed the limit.
 For heavy-haul transportation, ensure that
the bridge is capable of sustaining the
special load.
Effects:
 Fatigue and deterioration such as corrosion
may lead to the ultimate failure of the
structural member and therefore must be
controlled periodically.
Treatment:
 Ensure at the design time that the effects of
fatigue and deterioration are limited
and/or controlled.
 Estimate at the design time the required
periodicity of bridge maintenance and
inspection.
 Conduct the necessary inspections properly.
Effects:
 Reduction of capacity due to elevated
temperatures.
 Expansion of the members and bridge
deck may cause additional forces.
Treatment:
 Add fire protection systems to sensitive
members.
 Ad design time, consider the fire loading
as per standard specifications.
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LONG-SPAN BRIDGES (ENGM052)
Hazard, load
scenario
COURSEWORK 1
Likelihood
Severity
RIM
Ice
Remote
High
U
Earthquake
Occasional
Severe
U
Wind/Storm/
Hurricane
Occasional
Severe
U
Construction/Design
Remote
Medium
U
RAFAEL SCUDELARI DE MACEDO
Comment
Effects:
 The bridge deck, since it is fluctuating on
the air, has a higher tendency of creating
a freezing layer than the road that sits on
the ground. Therefore, this adds greatly to
the risk of collision.
 The snow load case must be considered at
design time.
Treatment:
 Ensure at design time that the snow load
case is properly considered.
 Ensure that there is no accumulation of
snow on the bridge deck.
Effects:
 High dynamic loading due to the ground
acceleration is transferred to the bridge
columns.
 May cause movement of the columns,
leading to deck failure.
 May cause, on sandy soils, the effect called
liquefaction, which may completely remove
the bearing capacity of columns.
 May cause the sudden strike-slip or change
in elevation of a geological fault.
Treatment:
 Avoid building the bridge over faults.
 Avoid building the bridge on soils that may
liquefy.
 Take into account, at design time, the
earthquake loads.
Effects:
 Wind loading causes horizontal forces on
the structure.
 May cause resonance effects which result in
large amplifications of displacement.
 Extreme winds may cause vortex effects
that can add torsional forces.
Treatment:
 Ensure that the design considers the wind
loading in accordance with the standards.
 Extreme cases must be considered.
 Perform wind tunnel analyses for sensitive
structures to minimize the possibility of
resonance effects and better understand
the wind pressures.
Effects:
 Engineering errors may cause the under
capacity of the structure.
 Erection of bridges may include complicate
and dangerous load handling.
 Ensure that the workplace safety practices
are followed.
Treatment:
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LONG-SPAN BRIDGES (ENGM052)
Hazard, load
scenario
COURSEWORK 1
Likelihood
Severity
RIM
Comment

Blast/Terrorist Attack
Improbable
Severe
U
Ensure that the design is well performed by
adding an independent peer-reviewer to
the design process.
 Ensure that the load handling is done by
expert personnel.
Effects:
 Blasts may cause sudden impact forces on
the structure, which are very difficult to
predict.
Treatment:
 Ensure the safety of the relevant structures
at public level.
 Avoid disproportionate collapse on design.
2.3 MOST IMPORTANT LOAD CONSIDERATIONS
In the opination of the student, and in accordance with the data as presented in the references [2] and [3], the 3
most important load cases are:
1. Flood
2. Collision with a vehicle
3. Overloading
2.4 REMARKS
The student finds it important to highlight that the English government recommends, in its “The Building Regulations
2010: Structure A” [4], that:
A3: The building shall be constructed so that in the event of an accident the building will not suffer collapse to an
extent disproportionate to the cause.
This is also appreciated in the EUROCODES. Specifically, the documentation on accidental actions BS EN 1991-17:2006+A1:2014 [5] contains recommendations on the robustness of the structure. Increasing the robustness of the
structure is one of the strategies recommended to mitigate the risk of accidental actions.
Therefore, the recommendations treat accidental actions in a way that the designer ought to analyses the
accidental effects on the structure in order to avoid that a relatively small action cause the collapse of the entirety
of the structure.
RAFAEL SCUDELARI DE MACEDO
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
3 ITEM 2: CABLE STAYED BRIDGE
Question Text: 2) Describe on no more than two A4 pages, with the use of sketches, the main elements of a typical
Cable Stayed Bridge and their main functions in the overall behavior of the structure. If a 500m span cable stay
bridge is planned what is your estimate of bridge deck depth and pylon height above deck level? [1]
3.1 DESCRIPTION OF TYPICAL ELEMENTS
Cable stayed bridges are bridges in which the vertical load of the
bridge deck (including its self-weight) is largely supported by a
series of cables that are directly connected to a central tower at
an angle. The structural behavior of the cable stayed bridge is
self-contained in the sense that the stability is ensured by the
cables, deck and pylon working together to balance the deck on
both sides.
Figure 2 displays the basic load distribution of cable stayed
bridges. In this form of bridge, the vertical load due to the weight
of the deck and of the vehicles are held by the vertical component
of the cable axial forces. This in turn produces a horizontal
FIGURE 2: BASIC LOAD DISTRIBUTION.
resultant that is balanced by the compression on the deck. On the
pylon, the axial forces of the cables cause a compression that is finally transferred to the foundations. The
horizontal forces on the pylon due to the cables are largely countered by the cable forces from the other side, but
there are some designs in which the bending resistance of the pylon takes a substantial part of this load.
A basic arrangement of the elements of the cable stayed bridge is shown in Figure 3.
The pylons are towers with a height H above deck of something close to 25% the span length L. Considering that
the resulting axial load on the stays is dependent on its angle, the height of the pylon ultimately influences the
sizing of the stay members and the overall cost of the structure. The pylons may be constructed in steel, concrete,
or composite. They may have several
different shapes, being the I, H and A shape
the most common. The A shape is generally
used when the bridge has only one plane of
cables that are connected to the center of the
deck. In turn, this obliges that the deck to
present a higher bending and torsional
resistance.
The positioning of the pylons is crucial for
the entirety of the project. They influence the
span length and usability (such as the volume
of the passage underneath, be that for road
FIGURE 3: CABLE STAYED BRIDGE ELEMENTS.
or maritime traffic) aspects. They must be
strategically positioned with the following main items taken into consideration:


Considering the risks of flood, scour and collision, the designer must avoid putting them in the water. If
there is no way to circumvent this, the designer must avoid positioning the pylons inside the navigable
channel and should give preference to shallow waters.
Consideration must be given to the side span. The support of the side spans is an important aspect of the
general stability of the structure and they should exist. Alternatives to the design, with either a shorter side
span or the elimination altogether of the span do exist, but they tend to increase the cost of the project.
The height under the deck of the pylons must consider the deck height, the usability aspects of the bridge (volume
of the passage underneath), the deformation of the structure under traffic and other variable loads and give
allowances for the shift on water level of the navigable channel.
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
The type of the section of the pylon, which is usually a box section, is
also important. Not only they influence the customary structural behavior
and highly influence the cost of the structure, but they also have, as
shown in [6], a large influence on the robustness of the structure against
blast loads.
Fan
Mix
There are several different forms of cable arrangements, but the most
Harp
common are fan, harp or a mixture of the two (shown in Figure 4). Their
typical spacing on the deck is of 8 to 10 meters. Since, in the fan type,
FIGURE 4: CABLE ARRANGEMENTS. SOURCE: [9]
the angle of the cables increase as the cables are closer to the pylon
thus yielding a lesser axial load, the fan arrangement usually provides
a smaller total cable weight. Single cables should be avoided, since they present a great problem when it comes
to maintenance (lack of redundancy).
The cables may be of several types, such as with parallel wires, spiral wires or locked coils. Regardless of the
arrangement, they must be protected against water infiltration and must be protected against corrosion.
Therefore, they are usually coated and galvanized, bathed in grease, with a HDPE duct around them.
The design of the bridge deck is governed by transit requirements, but they usually have a depth of 1 to 3
meters, being naturally deeper if a lower deck for train is used.
Considering that the horizontal components of the cables are countered by the bridge deck, it must be able to
resist this compression force and provide the transverse and torsional resistance required for the overall stability
of the structure. The stay arrangement may contain two or one single plane, and this influences the deck design. If
one plane is chosen, the connection will be on the center of the deck and it must provide adequate torsional
stiffness.
There is a wide choice available for the bridge deck. When two cable planes are chosen, it is normal that the
bridge deck will be made either with steel or concrete beams that run between the stay cables and that are
transversely locked by secondary members. This is possible in this case due to the lower torsional requirements.
When one plane of stays is preferred, the design of the bridge deck tends to go towards a solution with box
girders for they are capable of providing the required torsional stiffness. It is important to note that the design of
box girders must allow access to the inside for inspection and maintenance.
The width of the bridge deck is governed by traffic requirements, but it must be wider than the simple traffic
lanes to accommodate the stays – be them on a single plane in the center or at both sides – and also for
protection barriers.
The bridge deck must also consider aerodynamic effects. Regardless of the choice between a box girder or
beams, the lateral, top and lower sides of the deck must be designed considering wind loads and its dynamic
effects such as resonance.
It is common to use, as a strategy to improve the balance of the bridge and make a shorter side span, to use steel
on the central span and concrete on the side spans. Since concrete yields a heavier structure, the side spans will be
more effective when balancing the weight of the main span’s deck. Another common way to improve the balance
of the bridge is to add on the side spans intermediate columns to which the deck is attached on the position of
some stays. These columns will provide a vertical restraint and assist the general balance of the bridge.
3.2 500M SPAN BRIDGE
The premises of the coursework [1] state that the bridge is a footbridge, which yields lower live loads. Therefore,
using the chart in Figure 12 of the lecture notes [7], the student considers that depth of 1.5m is adequate for the
deck depth, being the deck a steel girder
For the height of the pylon above deck, the student takes the customary relation of it being 25% of the span. This
is due to the fact that the pylon height influences the cable angle and the student prefers to optimize the cable
axial forces and their costs. Thus, the height of the pylon is taken as H=500*.25=125m.
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
4 ITEM 3: SUSPENSION BRIDGE
Question Text: 3) Describe on no more than two A4 pages, with the use of sketches, the main elements of a typical
Suspension Bridge and their main functions in the overall behavior of the structure. If a 500m span suspension bridge
is planned what is your estimate of bridge deck depth and tower height above bridge deck level? [1]
4.1 DESCRIPTION OF TYPICAL ELEMENTS
The main structural characteristic of the suspension
bridge lies on its main cable. The vertical load of the
bridge deck (including its self-weight) is supported by
horizontal tension members called hangers. The top of
the hanger is attached to the main cable that usually
runs as a unique cable from the anchors on the
FIGURE 5: SUSPENSION BRIDGE'S MAIN LOAD PATH.
external sides of the two towers. This causes an axial
force on main cable that is held, usually by sheer friction against the ground, by the anchorage blocks. The
vertical forces of the system are held by the towers, which transmit them to the foundations. This basic system is
illustrated in Figure 5.
A typical suspension is shown in Figure 6.
The towers may be made on concrete, steel
or composite structure. They are usually
composed of two parallel towers having
several horizontal crossbeams to increase
their stability and reduce the buckling length.
The cross section of the towers is usually a
hollow section to reduce costs on materials,
but their shape should also consider the
possibility of accidental actions as per [6].
FIGURE 6: SUSPENSION BRIDGE MAIN ITEMS.
The work conducted by Hashemi et. al. exhibits that, since the pressure loads from a blast neat the towers depend
on the angle between the source and the surface’s normal and, therefore, a circular section would bring the
optimum robustness against accidental loads.
The positioning of the towers, as it was already stated in the answer of question 2 of this coursework, is crucial
for the project. The positioning must account for the specifications on the volume of traffic underneath and the
designer should avoid putting the towers on water due to risk of flood and scour. Specifically, for the suspension
bridges, care must be taken in order to allow the main cable on the side spans to softly descend. If the cable is
allowed to descend following its natural catenary until the cross section of the cable is vertical, the anchorage will
have to account for a lower cable axial force, since its resultant at that location will only have its horizontal part.
As it was for the pylons of the cable stayed bridge, the tower height under the deck of the suspension bridge
must also consider the deck height, the usability aspects of the bridge (volume of the passage underneath), the
deformation of the structure under traffic and other variable loads and give allowances for the shift on water
level of the navigable channel.
The main cables may be either composed on site by a method called air spinning or they may be preformed
parallel wire strand (PPWS). The air spinning, which is a method in which a single wire is passed across the full
length of the bridge over and over until the number of desired wires is reached. Then, the cables must be carefully
arranged to ensure they all carry the same load. The PPWS system used bundles of prefabricated wires with the
full length of the bridge. Then, the bundles are laid over the towers. Care must also be taken to ensure that all the
bundles carry the same load. After the positioning of the wires with either method, they are compressed by a
special device which reduces the void inside to augment durability and reduce diameter. Finally, these cables must
be protected by paint, spray or another system.
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
On the top of the towers there are devices called saddles that fold softly the main cable and allow it to run over
it if necessary. These saddles transmit the vertical load from the main cables to the towers.
The hangers are usually spaced between 10 to 15m and are habitually vertical. A diagonal arrangement may
be used, which increases the rigidity of the cable system with the drawback of inserting fatigue issues. The
hangers are attached to the sides of the bridge deck and to the main cable. These attachments must be carefully
designer to avoid fatigue issues. The device that makes the attachment between the hangers and the main cable
usually consists of a system that compresses a “bracket” against the cable. The forces are transmitted from the
hanger to the main cable by friction.
The main cables are horizontally loose on top of the towers, therefore, the only horizontal restraint in the entirety
of the system that counterbalances the horizontal axil force of the main cable is done by anchorage system. The
anchorage provides the termination for the main cable and must resist its horizontal forces. This may be achieved
by either making the anchorage on a tunnel if hard rock exists on the site’s ground profile, but usually the
anchorage consists of a heavy concrete hollow block. It is hollow to allow maintenance access to it and it must be
heavy because the majority of the horizontal forces is held by friction of the block against the ground. Usually, the
weight of the block must be 4 times the horizontal force of the main cable.
The design of the bridge deck is governed by traffic requirements. Added to the lane’s width must be space to the
protection systems and hanger supports. The profile of the bridge deck may be of several different forms, such as
steel truss, concrete or steel girders, concrete or steel box girders, etc. The steel truss is mainly used in the cases
where two traffic levels are required, whereas due to lack of torsional stiffness the simple girders are not used
commonly nowadays.
The modern bridges mostly use box girders due to their suitability in terms of torsional stiffness. In these box
girders, longitudinal stiffeners must be added to the plates so that they are more orthotopically rigid to support
traffic loads. Diaphragms must be added every 2 or 3 meters and personnel access must be provided for
maintenance. Their design must account for aerodynamic effects and preferably the bridge will undergo a wind
tunnel test.
It is good practice to consider removal of one hanger in the load cases during design. This improves the
robustness of the structure against accidental loads and also facilitates maintenance.
4.2 500M SPAN BRIDGE
The premises of the coursework [1] state that the bridge is a footbridge, which yields lower live loads. Therefore,
using the chart in Figure 13 of the lecture notes [8], the student considers that depth of 1.5m is adequate for the
deck depth, being the deck a steel girder.
For the height of the tower above deck, the student takes the customary relation of it being 10% of the span.
Thus, the height of the tower above deck is taken as H=500*.1=50m.
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LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
5 ITEM 4: MULTI SPAN
Question Text: 4) If a multi span cable stay or multi span suspension bridge with shorter spans was to be considered,
describe on no more than one page of A4 paper the factors affecting the conceptual design of this multi span
structure. [1]
5.1 FOR BOTH CASES

Usually multi-span bridges have a tower/pylon on the water. Special care must be taken regarding:
o Flood
o Scour
o Collision
5.2 CABLE STAYED BRIDGE
The main aspects that affect the conceptual design are exhibited in the image below.
FIGURE 7: EFFECTS OF LOADING ON MULTI-SPAN CABLE STAYED BRIDGES. SOURCE: [9]
It is possible to note that the loading on the center has direct effects on the displacements of the other spans, and
this must be accounted for in the design. The effects may be such as additional bending moments on the pylons,
increased loading on the cables, etc.
Other aspects are:


The height of the pylons will be smaller, since they are a function of the free span length.
Since there will be less vertical forces (the length deck for each tower is shorter), the deck will also sustain
lower compressive effects and therefore may be shallower.
5.3 SUSPENSION BRIDGE
Multi span suspension bridges present a heavier change into the conceptual design than that of multi span cable
stayed bridges. Either the designer adds intermediate anchorage and thus creates several single span bridges, or
a single main cable is passed and thus the stiffness of the entirety of the bridge is affected. Regardless of the
solution, the connection of the decks of the spans present problems such as illustrated in Figure 8.
FIGURE 8: EFFECTS OF LOADING ON MULTI-SPAN SUSPENSION BRIDGES. SOURCE: [10].
The main aspects that affect the design are:



Additionally, to the tower underwater, multi span suspension bridges also may provide anchorage in the
middle of the span. Although it is true that the same intermediate anchorage may be used by both sides
(thus providing a considerable balancing from both sides), this can prove to be a challenging and
expensive ordeal due to:
If the designer opts to have only one main cable that passes over several towers, then he must account for
stiffness problems such as described in detail in [11].
The height of the towers will be smaller, since they are a function of the free span length.
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
13
LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
6 ITEM 5: TABLE OF NOTABLE MULTI SPAN BRIDGES
Question Text: 5) Prepare a table of recent and notable multi span cable stay or multi span suspension bridges.
Tabulate; bridge name, year of construction, longest span and bridge length. [1]
Note: Since no minimum count of entries is given, the student considers 18 to be a reasonable sum. The source of
this information is the International Database for Civil and Structural Engineering website [12].
Type
Suspension
Suspension
Suspension
Suspension
Suspension
Suspension
Suspension
Suspension
Suspension
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Cable Stayed
Name - Country
Ma'anshan Bridge - China
Taizhou Bridge - China
Yingwuzhou Yangtze River Bridge - China
Barito River Bridge - Indonesia
Dhodhara-Chandani Suspension Bridges - Nepal
Sarnora Machel Bridge - Mozambique
Bonny-sur-Loire Bridge - France
Momosuke Bridge - Japan
Chatillon Bridge - France
Erqi Yangtze River Bridge - China
Rio-Antirrio Bridge - Greece
Ting Kau Bridge - China
Jiashao Bridge - China
Yiling Yangtze River Bridge - China
Millau Viaduct - France
Mezcala Viaduct - Mexico
General Rafael Urdaneta Bridge - Venezuela
Murom Oka River Bridge - Russia
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
Year Span (m) Length (m)
2013
1080
11209
2012
1080
2960
2014
850
2100
1997
240
1096
2005
1452
225
1973
180
90
1951
120
360
1922
104
248
1951
76
328
2011
616
2922
2004
560
2880
1998
450
1675
2013
428
10138
2001
3246
348
2004
2460
342
1993
312
884
1962
37
8700
2009
321
1340
14
LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
7 REFERENCES
[1] D. Collings, "LONG SPAN BRIDGES - COURSEWORK 1," 2017. [Online]. Available:
https://surreylearn.surrey.ac.uk. [Accessed 2017].
[2] L. Deng, W. Wang and Y. Yang, "State-of-the-Art Review on the Causes and Mechanisms of Bridge
Collapse," J. Perform. Constr. Facil., vol. 30, no. 2, 2016.
[3] K. Wardhana and F. Hadipriono, "Analysis of recent bridge failures in the United States," J. Perform.
Constr. Facil., vol. 17, no. 3, p. 144–150, 2003.
[4] Department for Communities and Local Government, "The Building Regulations 2010: Structure:
Approved Document A," 2013. [Online]. Available:
https://www.gov.uk/government/uploads/system/uploa
ds/attachment_data/file/429060/BR_PDF_AD_A_2013.pdf. [Accessed 2017].
[5] European Committee for Standardization, BS EN 1991-1-7:2006+A1:2014 - Eurocode 1 — Actions on
structures - Part 1-7: General actions — Accidental actions, Brussels: CEN, 2014.
[6] S. K. Hashemi, M. A. Bradford and H. R. Valipour, "Dynamic response and performance of cable-stayed
bridges under blast load: Effects of pylon geometry," Engineering Structures, pp. 50-66, 15 April 2017.
[7] D. Collings, "Lecture Notes - UNIT 1C - Introduction to Cable Stayed Bridges," University of Surrey,
Gildford, 2017.
[8] D. Collings, "Lecture Notes - UNIT 1B - Introduction to Suspension Bridges," University of Surrey,
Guildford, 2017.
[9] Johns Hopkins University, Whiting School of Engineering, "Cable-Stayed Bridges - History, Aesthetics,
Developments," [Online]. Available: http://www.ce.jhu.edu/perspectives/protected/lectures/2012
/Lec12_cablestayed_2012.key.pdf.
[10] D.-H. C. Huu-Tai Thai, "Advanced analysis of multi-span suspension bridges," Journal of Constructional
Steel Research, vol. 90, pp. 29-41, 2013.
[11] D. Collings, "Multiple-span suspension bridges: state of the art," Bridge Engineering, vol. 169, no. BE3, p.
215–231, 2016.
[12] N. Janberg, "The Largest Database for Civil and Structural Engineers," Structurae, 2017. [Online].
Available: https://structurae.net/. [Accessed 2017].
[13] Univerza v Ljubljani, "Lecture 15B.8: Cable Stayed Bridges," 2016. [Online]. Available: http://fggweb.fgg.uni-lj.si/~/pmoze/esdep/master/wg15b/l0800.htm. [Accessed 2017].
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
15
LONG-SPAN BRIDGES (ENGM052)
COURSEWORK 1
8 AUTHOR’S SIGNATURE
__________________________________
Eng. Rafael Scudelari de Macedo
CREA-PR 111.542/D
RAFAEL SCUDELARI DE MACEDO
6399594 – RS00742@SURREY.AC.UK
16