Brief Description of Bridges in Hilly Areas

1. Traffic Analysis of Gomti Nagar with respect to Pedestrian Facilities
SRMGPC LUCKNOW [INDIA]
Seminar
Topic- Bridges In Hilly Challenges
By
Abhinav [1112200004]
Under Guidance of-
Mr. Gangesh Kr. Kasaudhan
Asstt. Professor
Department of Civil Engineering

2. Introduction
• A Bridge is a structure build to span a valley, road, river, body
of water, or any other physical obstacle.
• Designs of Bridges will vary depending upon the function of
the bridge and nature of the area where the bridge is to be
constructed.
• The first bridges were made by nature itself—as simple as a
log fallen across a stream or stones in the river.
• The first bridges made by humans were probably spans of cut
wooden logs or planks and eventually stones, using a simple
support and crossbeam arrangement.
• Some early Americans used trees or bamboo poles to cross
small caverns or wells to get from one place to another.

3. Ctd.
• A common form of lashing sticks, logs, and
deciduous branches together involved the use of long reeds
or other harvested fibers woven together to form a
connective rope capable of binding and holding together
the materials used in early bridges.
• Hilly region pose unique problem for bridge construction. In
a restricted hilly area itself climatic conditions, geological
features and hydrological parameters vary considerably.
• Keeping in view the bridge site and various constraints,
type of bridge and method of construction are to be
selected carefully for safe, economical and
successful completion of bridge construction.

4. Fig.1 History of Bridge Development

5. Challenges in Hilly Area Bridges
Construction
Various challenges that come across while constructing bridges
in hilly area are:
• Construction of bridge across deep gorges;
• Construction of bridge on rivers with boundary beds;
• Construction of bridges in extreme temperature zones;
• Construction of bridges on sharp turn on highway;
• Landslide or Debris flow.

6. Bridge Foundation and Substructure
• Foundation construction for any large bridge takes time.
• Problems encountered during construction of foundation depend upon
type of foundation, soil strata encountered, equipment/plant deployed
and logistic problems. Construction difficulties anticipated during the
execution be kept in view while planning the works/ period for the job.
• Foundation can be opened foundation, pile foundation, well foundation or
any other types of foundation.
• In case of well foundation, the various type of soil are encountered and it
becomes difficult to give any clear time schedule about the sinking of
wells unless the soil details are very clear and the anticipated profile
matched with the actual encountered.
• In case of boundary and clayey soil the rate of sinking schedule is likely to
be slow when compared with the sandy soil.
• Also there may be requirement of pneumatic sinking technique
subsequent to open grabbing due to difficulties in sinking of well.

7. Superstructure
• For particular site there are numerous structural arrangements
possible.
• Final proposal be made based on the greater examination of site
condition may be technical, aesthetic and construction
methodology.
• Special care need to be taken in case of deep gorge where there is
sizable difference between soffit level and bed level. This may pose
difficulties for staging and shuttering.
• Proposal recommended for site should be well read in advance.
After the proposal has been finalized for particular bridge, the
construction can be planned.
• The quantities of each items involved and execution method be
listed. Basically method statement should be kept ready for overall
execution including job estimate.

8. Plant Management
Requirement of equipment/plant be assessed systematically
and accordingly action may be taken to arrange this for a
particular job.
• Quantum of work covering all the items with specifications;
• Time available for work execution;
• Details of equipment and also minimum requirement as per
job position;
• Rated capacity of equipment/ plant;
• Assessed capacity;
• Schedule of maintenance;
• Inventory of spare parts required;
• Repair cover to equipment/plant.

9. Material Management
• Material management is a parallel activity along
with start of the Project.
• This cover procurement of camp material, office
equipment, major purchased items, such as
aggregates, sand, cement, steel, structural steel,
shuttering consumables, electrical fittings.
• Forecasting of quantities and cost of various
items on monthly basis must be done at least
three to six months in advance which should be
regularly reviewed.

10. Finance Management
• No project and implimentation or project and implimentation
management can be meaningful without this.
• In case of Government work the manager should get his
budget fixed on monthly basis, on the basis of work done or
minimum to be fed at site, on the decision of higher
authorities.
• Key to measure financial planning lies in taking all above
action and taking suitable measures at appropriate times to
ensure that individual inputs are achieved to the maximum
and capital investment kept at the lowest level.

11. Types of Hilly Area Bridges
• Beam Bridge;
• Truss Bridge;
• Cantilever Bridge;
• Arch Bridge;
• Tied-Arch Bridge;
• Suspension Bridge;
• Cable-Stayed Bridge.

12. Beam Bridge
• Beam bridges are the simplest structural forms for bridge
spans supported by an abutment or pier at each end.
• No moments are transferred throughout the support,
hence their structural type is known as simply supported.
• The simplest beam bridge could be a stone slab or
a wood plank laid across a stream.
• Bridges designed for modern infrastructure will usually
be constructed of steel or reinforced concrete, or a
combination of both.

13. Fig.2 Beam Bridge

14. Truss Bridge
• A truss bridge is a bridge whose load-bearing superstructure is composed
of a truss, a structure of connected elements forming triangular units.
• The connected elements may be stressed from tension, compression, or
sometimes both in response to dynamic loads.
• Truss bridges are one of the oldest types of modern bridges.
• The basic types of truss bridges shown in this article have simple designs
which could be easily analyzed by 19th- and early 20th-century engineers.
• A truss bridge is economical to construct because it uses materials
efficiently.
Fig.3 Truss Bridge

15. Cantilever Bridge
• A cantilever bridge is a bridge built using cantilevers, structures that project
horizontally into space, supported on only one end.
• For small footbridges, the cantilevers may be simple beams; however, large
cantilever bridges designed to handle road or rail traffic use trusses built
from structural steel, or box girders built from prestressed concrete.
• The steel truss cantilever bridge was a major engineering breakthrough when
first put into practice, as it can span distances of over 1,500 feet (460 m), and
can be more easily constructed at difficult crossings by virtue of using little or
no falsework.
• A simple cantilever span is formed by two cantilever arms extending from
opposite sides of an obstacle to be crossed, meeting at the center.
Fig. 4 Cantilever Bridge Components
Fig. 5

16. Fig. 6 Howrah Bridge

17. Arch Bridge
• An arch bridge is a bridge with abutments at each end shaped
as a curved arch.
• Arch bridges work by transferring the weight of the bridge and
its loads partially into a horizontal thrust restrained by the
abutments at either side.
• A viaduct (a long bridge) may be made from a series of arches,
although other more economical structures are typically used
today.
Fig. 7 Zhijinghe River Bridge

18. Tied-Arch Bridges
• A tied-arch bridge is an arch bridge in which the outward-directed
horizontal forces of the arch, or top chord, are borne as tension by the
bottom chord, rather than by the ground or the bridge foundations.
• Thrusts downward on such a bridge's deck are translated, as tension, by
vertical ties of the deck to the curved top chord, tending to flatten it and
thereby to push its tips outward into the abutments, like other arch
bridges. However, in a tied-arch or bowstring bridge, these movements
are restrained not by the abutments but by the bottom chord, which ties
these tips together, taking the thrusts as tension, rather like the string of a
bow that is being flattened. Therefore, the design is often called
a bowstring-arch or bowstring-girder bridge.
Fig.8 Tied-Arch Bridge

19. Suspension Bridge
• A suspension bridge is a type of bridge in which the deck (the load-bearing
portion) is hung below suspension cables on vertical suspenders.
• The first modern examples of this type of bridge were built in the early
19th century.
• Bridges without vertical suspenders have a long history in many
mountainous parts of the world.
• This type of bridge has cables suspended between towers, plus
vertical suspender cables that carry the weight of the deck below, upon
which traffic crosses.
• This arrangement allows the deck to be level or to arc upward for
additional clearance.
• Like other suspension bridge types, this type often is constructed
without falsework.
Fig.9 Capilano Suspension Bridge

20. Cable-Stayed Bridge
• A cable-stayed bridge has one or more towers (or pylons), from
which cables support the bridge deck.
• There are two major classes of cable-stayed bridges: harp and fan.
• In the harp or parallel design, the cables are nearly parallel so that the
height of their attachment to the tower is proportional to the distance
from the tower to their mounting on the deck.
• In the fan design, the cables all connect to or pass over the top of the
towers. The fan design is structurally superior with minimum moment
applied to the towers but for practical reasons the modified fan is
preferred especially where many cables are necessary. In the modified fan
arrangement the cables terminate near to the top of the tower but are
spaced from each other sufficiently to allow better termination, improved
environmental protection, and good access to individual cables for
maintenance.
• The cable-stayed bridge is optimal for spans longer than cantilever
bridges, and shorter than suspension bridges.

21. Fig.10 Cable stayed Bridge over Cooper River

22. Conclusion
• All bridges held generally the same amount of weight. The arch bridges
held a little more than the other bridges. They were in the 1400-1500
gram range. The other bridges were in the 1000-1200 gram range.
• The bridges would not stand up on their own, so a support at each end
had to be constructed. Balancing the weights on the bridges required
patience. Clamps were used to hold the bridges during gluing.
• The bridges supported different amounts of weights because each type
has different construction. The arch bridges supported the most weight
because of the great natural strength of the arch. The pier bridges
supported the least weight because the supporting piers broke during
construction.

23. Thank You