Prestressed Concrete Bridge.pptx

CONCERETE

1. Planning, Analysis & design Of Prestressed Concrete Bridge

2. Prestressed Concrete

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/ .  

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/ . P.C.C (1:5:10) mix using 40mm stone aggregate is provided as levelling course for pier footings. The footings are provided in 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, - grade concrete is provided and 900 N/ – 1500 N/ 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 grade of concrete and deck slabs are constructed using - 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

10. PLAN

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 Design of interior panel. Shear force. Dead load bending moment and shear force. Design moment and shear. Design of slab and reinforcement. Check for shear stress. Design of longitudinal girder. Check for ultimate flexural strength. Design of end block.

13. Design of beam B =800 mm D =1600 mm L =30 m F ct = 16 N/mm 2 Loss ratio = F u = f tw = 1.4 N/mm 2 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 Design the Rocker pin 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/ 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/ 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, Dimension Lateral reinforcement Lateral reinforcement near the pile head 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.

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