BANSAL INSTITUTE OF ENGINEERING AND TECHNOLOGY LUCKNOW

SUMMER TRAINING REPORT ON BOX GIRDER BRIDGE & POST TENSIONING SYSTEM OF PRESTRESS

Submitted By

WASEEM SAJAD

(ROLL: NO: - 1342200175)

BATCH: - 2013-17

TRAINING SITE: - Construction of 265m long bridge on Jammu Poonch highway (NH144A) at Kalai.

CLIENT: - BORDER ROAD ORGANISATION (BRO)

CONTRACTOR: - A. K. CONSTRUCTION.

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ACKNOWLEDGEMENT

The training opportunity I had with A. K. Construction Builders and Engineers was

a great chance for learning and professional development. Therefore, I consider

myself as a very fortunate individual as I was provided with such an

opportunity. I am also grateful for having a chance to meet so many wonderful

people and professionals who led me though this internship period.

I am highly indebted to Mr. Sikander Khajuria (Project Manager) and Mr.

Tarseem Kumar (Work Supervisor) for their guidance and constant supervision as

well as the kind support throughout the internship. I also extend my heartiest thanks to

all the present Engineers and staff members working in the office including Engineers

and Officers of B.R.O. who have willingly helped me out with the best of their

abilities. Also to the faculties who shaped my knowledge to tackle all problems

in smart and most efficient way.

I also express my gratitude towards all others who whole heartedly helped my

during my internship period.

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ABSTRACT

The report mainly consists of various parts in which I tried to explain my six week

training experience in my hosting company, A.K. Constructions Builders and

Engineers. The content of all chapters is broadly explained and it is constructed from

the practical basis of work.

Initially, I give details about the importance of the project in respect of

connectivity, international trade, defense and related aspects and basic concepts about

Bridge especially Box Girder type.

The second part is the most important one which explains my overall training

experience which comprises Box Girder Bridge, Ready Mix Concrete Plant and most

importantly Post Tensioning system of Prestressing. This chapter is the record of the

overall work I have been executing. It gives a highlight of what I have been doing

during my training period.

After all those chapters explained above I move on to the third chapter and

explain the main benefits of the internship in terms of different aspects and areas. It is

obvious that the internship has a positive outcome in terms of improving skills and

different abilities as a whole. The advantages and gains of the internship are put in

short and precise way to grasp the attention of readers and evaluators.

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INDEX

S: No: - Contents Page: No:-

1. Importance of the project.------------------------------------------------------6

2. Basic about Bridges.-------------------------------------------------------------7

3. Box Girder Bridge. ---------------------------------------------------------------8

4. Project detail. ----------------------------------------------------------------------9

5. Piers. ------------------------------------------------------------------------------------11 Foundation. -------------------------------------------------------------------------------11 Vertical Shaft. ----------------------------------------------------------------------------13 Pier Cap. -----------------------------------------------------------------------------------13

6. Box Girder. -----------------------------------------------------------------------------13

7. Abutment.-------------------------------------------------------------------------------16

8. Mix Design. ----------------------------------------------------------------------------18

9. Prestressing. ---------------------------------------------------------------------------19 Prestressing Process. ------------------------------------------------------------------19 Procedure. -------------------------------------------------------------------------------23 Distressing. -------------------------------------------------------------------------------25

10. Conclusion------------------------------------------------------------------------------- 27

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IMPORTANCE OF THE PROJECT :-

The importance of Kalai Bridge Project is explained in following important aspect:-

Permanent Connectivity:Kalai Brigde is one of the two bridges that connect two Tehsils (Tehsil Haveli and Tehsil Mandi) with rest of the country over river Poonch. The other bridge Sher-e-Kashmir Bridge in Poonch town, however during the flood of 2014 and 2015 a major portion 10 km stretch of NH 144A leading from Kalai to Poonch got slide into the river at various places and also a portion of Sher-e-Kashmir Bridge got completely damaged leading to shift of whole traffic on Kalai Bridge. So to maintain permanent connectivity with whole country this project is very common.

Replacement of old steel truss bridge:The old Kalai Bridge is a single lane steel truss bridge and was built in early 1960s. Due to single lane it often leads to traffic jams. It also requires regular maintenance one in a week and during maintenance traffic is to be stopped. The load carrying capacity of this bridge is also very less so heavy vehicles are not allowed to cross over it. All these conditions lead to an urgent requirement of a new bridge.

Defense aspects:Being very close to the Actual Line of Control this bridge always remain a major target of the enemy and has been attacked many times. The old steel truss bridge is not much resistant to such attacks so a new structure is a must. More than 60% of the total army and BSF present in Poonch district have to cross over this bridge and reach their duty spots to guard the territory.

International trade:The international trade between India and Pakistan at Indo-Pak border (ALC) Chaka-da-Bagh started in 2008 and till now trade happens every Monday. A huge quantity of goods are imported and exported across the border. Kalai Bridge and Sher-e-kashmir bridge play a key role in transport of these goods.

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BASICS ABOUT BRIDGES :-DEFINATIONA bridge is a structure providing passage over an obstacle without closing the way beneath. The required passage may be for a road, a railway, pedestrians, a canal or a pipeline. The obstacle to be crossed may be a river, a road, railway or a valley. In other words, bridge is a structure for carrying the road traffic or other moving loads over a depression or obstruction such as channel, road or railway.A bridge is an arrangement made to cross an obstacle in the form of a low ground or a stream or a river without closing the way beneath.

COMPONENTS OF BRIDGE

The bridge structure comprises of the following parts.Superstructure or DeckingThis includes slab, girder, truss, etc. This bears the load passing over it and transmits the forces caused by the same to the substructures.BearingsThe bearings transmit the load received from the decking on to the substructure and are provided for distribution of the load evenly over the substructure material which may not have sufficient bearing strength to bear the superstructure load directly.SubstructureThis comprises piers and abutments, wing walls or returns and their foundation.

Piers and AbutmentsThese are vertical structures supporting deck/bearing provided for transmitting the load down to the bed/earth through foundation.

Wing walls and ReturnsThese are provided as extension of the abutments to retain the earth of approach bank which otherwise has a natural angle of repose.

FoundationThis is provided to transmit the load from the piers or abutments and wings or returns to and evenly distribute the load on to the strata. This is to be provided sufficiently deep so that it is not affected by the scour caused by the flow in the river and does not get undermined.

While the above mentioned are structurally operational parts, for safety hand rails or parapets, guard rails or curbs are provided over the decking in order to prevent vehicle or user from falling into the stream or for the separation of traffic streams.

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Common types of bridges.

S:No:-

Type Span range

1 Arch (masonry) 3-15 m2 Arch (steel) Upto 519 m3 Arch (concrete) Upto 305 m4 Slabs Upto 9m5 Girder and beams 10 - 60m (exception up

to 250m in continuous6 Trusses (simply supported) 30-375 m7 Trusses (with cantilever combination) 550m8 Suspension bridge 500m-1400m.9 Cable stayed bridge 300 to 600m.

BOX GIRDER BRIDGE :-Girder: - A girder is a support beam used in construction. It is the main horizontal support of a structure which supports smaller beams. Girders often have an I-beam cross section composed of two load-bearing flanges separated by a stabilizing web, but may also have a box shape, Z shape and other forms.

A box girder bridge is a bridge in which the main beams comprise girder in the shape of a hollow box. The box girder normally comprises either prestress concrete, structural steel or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section. Box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. Although normally the box girder bridge is a form of beam bridge box girders may also be used on cable-stayed bridge and other forms.

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PROJECT DETAIL :-

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Bridge type: - Box Girder Bridge.

Total length = 265m.

No. of spans = 5.

No. of Piers = 4.

Length of each span = 53m.

Total width of deck = 12m.

Carriageway width = 7.5m (2 lane)

Footpath = 1.5m on each side of carriageway.

Average height from ground level = 18m.

Concrete Mix used = M50 (for Piers)

M45 (for deck slabs and beams)

M40 (for abutments)

Founding level = 78.108 m (for pier P1)

84.0 m (for al other piers)

Lowest water level (LWL) = 89.40 m

Highest flow level (HFL) = 99.920 m.

Reduced traffic level (RTL) = 106.920 m.

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PIERS :-

o FOUNDATION:-

ELEVATION PLAN

SECTIONAL ELEVATION

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o VERTICAL SHAFT (STEM): 12

Reinforcement detail

Upto 8217mm from base of foundation:

Verticl reinforcement:

100Nos. 32 mmØ

Rings:

10 mm Ø @ 150 C/C

Above 8217 mm from base of foundation.

Verticl reinforcement:

50 Nos. 32 mmØ

Rings:

10 mm Ø @ 300 C/C

o PIER CAP:-

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Width of pier cap = 5.5 m. (at top)

2.65 m. (at bottom)

Thickness = 3.45 m.

Total height of pier cap = 1.5 m.

C/C of bearings = 4.3 m. (perpendicular to direction of traffic)

2.25 m. (along direction of traffic)

BOX GIRDER :-

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Total width of deck slab = 12m.

Carriageway width = 7.5m (2 lane)

Footpath = 1.5m on each side of carriageway

o Bottom flange:-Thickness = 450 mm.Width = 6.5 m.

o Web:-Thickness = 500 mm (near supports) 300 mm (at mid span)

o Deck slab:-Thickness = 400 mm. (near web)

250 mm (at center line)300 mm – 200 mm (for cantilever portion, footpath)

o Belister Block : -It is provided when cross-sectional area of box girder is not enough to provide sufficient no of profiles for prestressing, then additional required profiles are provided in Belister Block

ABUTMENT : -

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COUNTERFORTS TENSION REINFORCEMENT

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MIX DESIGN :-

o M-45 (Mix) 53 grade cement:-For 1 m3 of MixAggregate 20 mm. = 620 kg. 10 mm. = 623 kg.Sand = 630 kg.Cement = 479 kg.Water = 167 kg.Admixture = 5100g.

o M-40 (Mix) 43 grade cement:-For 1 m3 of MixAggregate 20 mm. = 620.45 kg. 10 mm. = 620.45 kg.Sand = 549.13 kg.Cement = 479 kg.Water = 167.45 kg.Admixture = 5148g.

o Admixture used: WRA admixtureSuper plasticizing admixtureSulphonated Napthaline

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PRESTRESSING

HYSD STRANDS USED: -

Total no. of profiles in each span = 26

6 in each web (total 12)

4 in bottom flange

10 in Belister block.

15.2mm 7 ply HYSD wire strand class II IS 14268 – 1995 uncoated stress relived LRPC strand.

E = 19163.76 kg f /mm2

Breaking Load = 27200 kgf.

Area = 143.50 mm2

PRESTRESSING PROCESS : -

PRESTRESSING METHOD USED :- (POST TENSIONING SYSTEM)

Force applied from one directional only.

MATERIAL USED DURING CASTING: 1. DUCT PIPES 2. HYSD STEEL WIRES STRANDS (CABLES) 3. GUIDE CONE

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(Grouting spout)

(HYSD strands) (Guide Cone)

EQUIPMENTS USED FOR TENSIONING (STRESSING): 1. BEARINGS

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Bearing

HYSD strands Guide cone Guide Cone

2. WEDGES (MASTER GRIP) (wedges allows only unidirectional motion of cable)

3. COLLAR

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4. ANCHOR BLOCK Star

Collar Plate

Anchor Block

5. JACK 6. STAR PLATE 7. HYDRAULIC PUMP 8. CRANE ( To lift and adjust jack )

JACK HYDRAULIC PUMP

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9. ALUMINIUM /STEEL PIPES OF SUITABLE DIA AND LENGTH .

PROCEDURE :- Place the duct pipes at designed position in smooth curves between the reinforcement with

guide cones at both ends of duct pipes and Insert designed no. of cables (HYSD strands) in duct pipes and cast the member. After designed no. of days stressing (tensioning) is done.

Clean all the cables with suitable solvent (petrol) and adjust bearing over cables at both ends.

Apply wax over wedges and grip them over cables to fix cables with bearings.

Fit the collar over bearing and adjust star plate on combination of collar and bearing

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Apply jack on above made combination then fit anchor block inside the jack.

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Connect the jack to hydraulic pump and stress the cables.

DISTRESSING :-

The case of distressing in case of some structural failure such as:

Breakdown of one or more cables from the bundle of cables. Breakdown of guide cone. Breakdown of prestressing member.(cracks) etc

In such cases sometime the whole member is to be recast and sometime it is just need only small repairs using mix with special admixtures and both cases most of the time cables are to be released of stress.

Once the strands get stressed, they get rigidly locked with master grips inside the bearing. To release stress first master grips are to be removed which can be done only by applying tensioning force to strands. All the strands cannot be released of stress at once it is done individually for each strand. For this purpose special type jack and another bearing with suitable arrangement is used.

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Jack for tensioning individual strands. Damaged guide cone.

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CONCLUSION

The training is a bridge between the theoretical knowledge and the practical or the real work at the field of construction or civil engineering work. The responsibilities of the hosting company are to teach student and shape them as a real site workers. My hosting helped me and my friends who took the internship session in this company in acquiring different knowledge in different positions.

In review this internship has been an excellent and rewarding experience. I have been able to meet and network with so many people that I am sure will be able to help me with opportunities in the future.

One main thing that I have learned through this internship is time management skills as well as self-motivation. When I first started I did not think that I was going to be able to make myself stand for eight hours a day at site everyday. Once I realized what I had to do, I organized my day and work so that I was not overlapping or wasting my hours. I learned that I needed to be organized and have questions ready for when it was the correct time to get feedback. From this training and at site I had to learn how to motivate myself through being in the office and at site for so many hours.

I enjoy this line of work, but I will keep my other options open. I will continue to work hard in my position and hope to continue to learn about the

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industry and meet new people. This was an excellent experience and I hope that other interns got as much out of it as I did!

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