3. ABSTRACT.
This project deals with the proposal of a PRESTRESSED CONCRETE BRIDGE. This structure consist of
Beam, peirs, girders and footing . And the PSC bridge decks constructed in two methods (i).Pretensioned prestressed
concrete bridge decks, (ii). Post-tensioned prestressed concrete bridge decks. Pretensioned prestressed concrete bridge
decks generally comprise precast pretensioned units used in conjunction with cast in situ concrete, resulting in composite
bridge decks which are ideally suited for small and medium span in the range of 20 to 30 m. Post-tensioned prestressed
concrete bridge decks are generally adopted for longer spans exceeding 20 m. This project relates the model of
‘KINATHTHUKKADAVU PRESTRESSED CONCRETE BRIDGE’ and mainly this bridge constructed the by the
advantages of, it provided for long span, it reduced the deflection and it can carry maximum of loads compared to
reinforced concrete bridges. Prestressed concrete(PC) technology is being used all over the world in the construction of a
wide range of bridge structures. However, many PC bridges have been deteriorating even before the end of their design
service-life due to corrosion and other environmental effects. In view of this, a number of innovative technologies have
been developed in JAPAN to increase not only the structural performance of PC bridge, but also their long-term
durability.
4. INTRODUCTION
PLANNING
The proposal of prestressed concrete bridge consists of deck slab, piers, bearings, footing
and other amenities of single span of PSC Bridge having the length of the span is 30 m.
SPECIFICATIONS
1.CLEANING THE SITE
The proposal area is to be cleaned of all the loose stones, plants, trees, materials, rubbish of
all kinds as well as of root of trees etc., entirely rubbed out.
2.EARTHWORK EXCAVATION
After cleaning the site, centre line of foundation lines for excavation is started. The
submerged unit weight of concrete is 9.5 N/𝑚𝑚2
.
5. FOUNDATION CONCRETE
The earth work excavation for the foundation is proposed to a depth of 2.0 m
below the ground level. For design, the submerged unit weight of the soil is
9.5 N/𝑚𝑚2.
P.C.C (1:5:10) mix using 40mm stone aggregate is provided as levelling
course for pier footings. The footings are provided in 𝑀20 grade concrete.
FOOTINGS
Footing are provided pile footing for the bridge consists of 16 group of 16
piles. And the length of the pile is 12 m spaced at 1.5 m c/c.
GRADE OF CONCRETE AND STEEL
For the PSC Bridge construction, 𝑀40 - 𝑀45 grade concrete is provided and
900 N/𝑚𝑚2 – 1500 N/𝑚𝑚2 grade steels are to be provided.
6. SUPERS STRUCTURE
The super structure includes the beam, deck slab, piers and bearings. The piers are
constructed using 𝑀20 grade of concrete and deck slabs are constructed using 𝑀40 - 𝑀45
concrete respectively.
DECK SLAB
The primary function of a bridge deck is to support the vehicular vertical loads and distribute
these loads to the steel superstructure. The deck is typically continuous along the span of the
bridge and continuous across the width of the span.
BEAM
A properly prestressed concrete beam can span longer distance than a reinforced concrete
beam and it is thinner, lighter in weight, and uses less concrete without cracking or breaking
PIER
A pier is a raised structure, including bridge and building supported by Widely spread piles or
pillars. The lighter structure of a pier allows tides and currents to flow almost unhindered,
whereas the more solid foundations of a quay or the closely spaced piles of a wharf can act as
a breakwater, and are consequently more liable to silting.
7. BEARING
Bearing are mechanical arrangements provided in the superstructure to transmit the
load to the substructure. They can be thought of as the interface or via media between the
superstructure and the substructure.
GIRDER
A girder bridge is perhaps the most common and most basic bridge. A log across a
creek is an example of a girder bridge in its simplest form. In modern steel girder bridges, the
two most common girders are I-beam girders and box-girders.
AGGREGATES
Is a granular material, such as sand, gravel, crushed stone and iron blast furnace slab,
and when used with a cementing medium forms a hydraulic cement concrete or mortar.
CEMENT
Cement is any material that hardens and becomes strongly adhesive after application in
plastic form. The term cement is often used interchangeably with glue and adhesive.In
engineering and building construction, the term usually refers to a finely powdered,
manufactured substance consisting of gypsum plaster or Portland cement that hardens and
adheres after being mixed with water.
8. PRESTRESSING TENDONS
Because of the high creep and shrinkage losses in concrete, effective
prestressing can be achieved by using very high strength steels in the range of 270,000 psi
or more.
9. DATA COLLECTION FOR PLANNING
PLANNING OF THE STRUCTURE
ANALYSIS OF THE STRUCTURE
METHODOLOGY
11. Types of designs.
1.Design of slab
2.Design of beam
3.Design of bearing
4.Design of pier
5.Design of well foundation
6.Design of pile foundation
12. Design of slab
The slab of the bridge is designed for 30 m span and 7.5 m carriage width.
The slab elements are to be designed under the following steps are to be considered
1. Design of interior panel.
2. Shear force.
3. Dead load bending moment and shear force.
4. Design moment and shear.
5. Design of slab and reinforcement.
6. Check for shear stress.
7. Design of longitudinal girder.
8. Check for ultimate flexural strength.
9. Design of end block.
13. Design of beam
B =800 mm
D =1600 mm
L =30 m
Fct= 16 N/mm2
Loss ratio = 𝜂 = 0.85
Fu = ftw = 1.4 N/mm2
The above data’s are to be used to design the bridge beam. And the following steps are to be
provided.
1.Check for adequacy
2. Prestressing force
3. Eccentricity
4. Design of web shear
5. Design of flexural
6. Area of steel required
14. Design of bearing
The bearing is designed for the purpose of allowed to control the movement and it can be
reduce the stresses involved. And it is provides a resting surface between the bridge piers and
bridge deck.
span = 30 m
Reaction = 2500 kN
In this bridge provides the rock and roller bearing is to designed.
The following steps are to be used to designed
1. Design the Rocker pin
2. Check for bearing stress
15. Design of piers
A structure built on posts extending from land out over the water.
Mean velocity of flow = 0.64 m/sec
Safe bearing capacity of soil = 350 kN/𝑚2
Span = 30 m
Thickness of wearing coat = 100 mm
Thickness of footing = 600 mm
The following design steps are to be followed.
1. Loading on super structure
2. Design the loading
3. Water current on pier
4. Wind force
5. Area of steel required.
16. Design of well foundation
A well foundation is designed for an abutment of 10 m × 5 m base dimensions. The
well foundation on a sandy soil.
Height of abutment = 6.0 m
Total vertical load = 12,000 kN
Total lateral load at the scour level = 400 kN
Submerged unit weight of soil = 9.5 kN/𝑚2
The above data’s is to be adopt the design the well foundation
Design steps
1. Calculation of length
2. Thickness of steining
3. Reinforcement
4. Bottom plug
5. Check for the section
17. Design of Pile foundation
Pile foundation is type of deep foundation which are generally used in high raise
building construction and bridge construction.
Bridge consists of piles = 16
Total load = 12,000 kN
Space = 1.5 m c/c
Depth = 12 m
The above data’s are to be used for pile foundation design.
Steps adopted for pile design are,
1. Dimension
2. Lateral reinforcement
3. Lateral reinforcement near the pile head
4. Lateral reinforcement near the pile end.
18. CONCLUSION
• 30 m Length Bridge is considered for analysis of precast pre-stressed concrete
bridges, and for all the cases, deflection and stresses are within the permissible limits.
• We can clearly see the effectiveness of using precast pre-stressed concrete girder
configuration as it gives us most of the design parameters within permissible limits
of serviceability, deflection and shear compared to ordinary deck slab configuration.
• To obtain even better working results the precast pre-stressed concrete girder
configuration deck slab can be subjected to pre/post tensioning. The pre-stressing
force can be applied more easily.
• Ordinary configuration of deck slab creates long term maintenance and serviceability
problems as it has more number of exposed components in the structure. This
problem can be overcome conveniently in case of precast pre-stressed concrete girder
deck slab configuration.
19. REFERENCES
• [1] IRC 6:2010, Standard Specifications and code of practice for Road Bridges Section II:
Loads and Stresses.
• [2] IRC 18:2000, Design Criteria for Prestressed Concrete Road Bridges.
• [3] IRC 21:2000, Standard Specifications and code of practice for Road Bridges Section
III: Cement Concrete.
• [4] IS 1343: 2012, Code of practice for Prestressed Concrete.
• [5] N. Krishna Raju, 1981, Prestressed Concrete, Tata McGraw-Hill Publishing Company
Limited.
• [6] S. Ramamrutham, Theory of Structures, Dhanpat Rai Publishing Company.
