| CONTENTS | ||
| 1. INTRODUCTION | ||
| 1.1 DEFINITION OF A BRIDGE | 2 | |
| 1.2 OTHER IMPORTANT DEFINITIONS | 2 | |
| 2. SITE INSPECTION | ||
| 2.1 SELECTION OF SITE | 5 | |
| 2.2 EXISTING DRAINAGE STRUCTURES | 5 | |
| 3. COMPONENTS OF BRIDGE | ||
| 3.1 FOUNDATION | 6 | |
| 3.2 SUB - STRUCTURE | 9 | |
| 3.3 BEARINGS | 11 | |
| 3.4 SUPER STRUCTURE | 12 | |
| 4. DESIGN OF STRUCTURE | ||
| 4.1 DESIGN LOADS & STRESSES | 17 | |
| 4.2 HYDROLOGY | 18 | |
| 4.3 SUB-SOIL INVESTIGATION | 18 | |
| 4.4 TEMPORARY WORKS | 18 | |
| 4.5 DESIGN | 19 | |
| 4.6 REINFORCED EARTH RETAINING | 21 | |
| STRUCTURES | ||
| 4.7 SAFETY BARRIERS | 23 |
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1.INTRODUCTION
1.1 DEFENITION OF A BRIDGE
A 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.
For bridges having length more than 60m, detailed estimate is required to be submitted to Govt. for obtaining Administrative Approval. It is, therefore, necessary that site is finalized by the Superintending Engineer, Designs Circle so that detailed soil explorations as may be necessary could be done by Road Project Divisions.
1.2 SOME IMPORTANT DEFINITIONS
Small bridge
Overall length of the bridge between the inner faces of dirt walls is up to 30m and where individual span is not more than 10m
Minor bridge
Total length up to 60m
Major bridge
Total length greater than 60
Culvert
A cross drainage structure having total length of 6 m or less between inner faces of dirt wall
Foot Bridge
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A bridge extensively used for carrying pedestrians, cycles and animals
High Level Bridge
A bridge, which carries the roadway above H.F.L. of the channel
Submersible Bridge/ Vented Causeway
A bridge designed to be overtopped during floods.
Clearance
| The | shortest distance between boundaries at | a | specified | position | of | bridge |
| structure | ||||||
| Freeboard | ||||||
| The | difference between H.F.L. (allowing afflux) and foundation level of road | |||||
| embankment on approaches | ||||||
H.F.L.
Highest flood level is the level of highest flood ever recorded or the calculated level for design discharge
L.W.L.
Lowest flood level is the level of the water surface obtained in dry season
Length of Bridge
The length of a bridge structure will be taken as overall length measured along the center line of the bridge between inner faces of dirt wall
Linear Waterway
Width of waterway between the extreme edges of water surface at H.F.L.
measured at right angles to the abutment face
Effective Linear Waterway
The total width of the waterway of the bridge at H.F.L. minus effective width of obstruction
Safety Kerb
A roadway kerb for occasional use of pedestrian traffic
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Width of Carriageway
Minimum clear width measured at right angles to the longitudinal centerline of bridge between inside faces of roadway kerb or wheel grades
Vertical clearance
The height from the design highest flood level with afflux of the channel to the lowest point of the bridge superstructure at the position along the bridge where clearance is denote
20. Bearings
The part of the bridge structure which bears directly all the forces from the structure above and transmits the same to the supporting structure
Abutment
The end supports of deck of bridge, which also retains earth, fill of approaches behind fully or partly
Spill through Abutment
An abutment where soil is allowed to spill through gaps along the length of abutment such as column structure where columns are placed below deck beams and gap in between is free to spill earth
Afflux
The rise in the flood level of the river immediately on the upstream of a bridge as a result of obstruction to natural flow caused by the construction of bridge and its approaches
Bearing Capacity
The supporting power of a soil / rock expressed as bearing stress is referred to as its bearing capacity
Foundation
The part of bridge is in direct contact with and transmitting load to the founding strata
Pier
Intermediate supports of the superstructure of a bridge
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Retaining Wall
A wall designed to resist the pressure of earth filling behind
Return Wall
A wall adjacent to abutment generally parallel to road or flared up to increase width and raised up to the top of road
Toe wall
A wall built at the end of the slope of earthen embankment to prevent slipping of earth and / or pitching on embankment
Wing Wall
A wall adjacent to abutment with its top up to R.T.L. near abutment and sloping down up to ground level or a little above at the other end. This is generally at 45 degrees to the alignment of road or parallel to the river and follows the profile of earthen banks
Substructure
The bridge structure such as pier and abutment above the foundation and supporting the superstructure. It shall include returns and wing walls but exclude bearings
Skew angle of Bridge
It is the angle between the perpendicular to the flow of traffic direction and the flow direction of river
2. SITE INSPECTION
2.1 SELECTION OF SITE
Where there is any choice, select a site:
(1) Which is situated on a straight reach of the stream, sufficiently below bends
(2) Which is so far away from the confluence of large tributaries as to be beyond their disturbing influence
(3) Which has well-defined banks
(4) Which makes approach roads feasible on the straight
In siting small bridges and culverts, due consideration should be given to the geometrics of the approach alignment and the latter should essentially govern the
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selection of site unless there are any special problems of bridge design.
2.2 EXISTING DRAINAGE STRUCTURES
If, by chance, there is an existing road or railway bridge or culvert over the same stream and not very far away from the selected site, the best means of ascertaining the maximum discharge is to calculate it from data collected by personal inspection of the existing structure.
It should be seen whether the existing structure is too large or too small or weather it has other defects. All these should be carefully recorded.
3. COMPONENTS OF BRIDGE
3.1 FOUNDATION
3.1.1 Depth of foundations
The foundation shall be taken to such depth that they are safe against Scour, or protected from it. Apart from this, the depth should also be sufficient from consideration of bearing capacity, settlement, stability and suitability of strata at the founding level and at sufficient depth below it.
Depth of shallow foundations may be taken down to a comparatively shallow depth below the bed surface provided a good bearing stratum is available and the foundation is protected
Selection of a particular type of foundation is a very important job as it affects the entire proposal for the bridge. On the other hand if scour depth is less and flood depth is also reasonably small the raft foundation could be the choice.
3.1.2 Important Points
The following points are to be noted while preparing bridge proposal.
(a) Span to height ratio for Raft foundation be kept as 1.00 to 1.25
Open foundation be kept as 1.25 to 1.50
Pile foundation be kept as 1.25 to 1.75
Well foundations it should be 1.50 to 2.00
(b) The dimensions of pier, abutment and well foundation to be taken from type
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designs or from the latest I.R.C. Codes.
(c) Proper uniform sitting of well foundation could be ensured by taking the foundation into rock by about 15 cm.
(d) The raft foundation details are taken from the type designs as applicable.
(e) Other similar designs prepared and approved by the Designs Circle should also be studied and referred to.
(f) Open foundations are comparatively easy to decide about.
(g) Anchorage of open foundation into the rock shall be as per IRC-78 i.e. minimum 0.60m into hard rock and 1.50 m into soft rock excluding scour able layers.
(h) Leveling course and annular filling should be proposed for open foundation. Annular filling should be done with M 15 concrete up to rock level.
(i) Stability of foundation should be worked out. The beginner should obtain the standard calculation sheets from office, and do the calculations manually to gain confidence.
3.1.3 FOUNDATION TYPES
Generally two types of foundations are adopted for bridge structures. (i) Shallow foundations - Open foundations - Raft foundations
(ii) Deep foundations - Pile foundations - Well foundations
Open Foundations
Open foundations are preferred over any other type. These are to be provided when good-founding strata are available at shallow depth and there is not much problem of dewatering. R.C.C. footings are preferred over P.C.C. footing in case of RCC piers.
Raft Foundations
Raft foundation is designed as R.C.C. solid slab. The additional component of cut off walls on both sides U/s and D/s was considered necessary to take care of seepage and possible undermining of the raft due to seepage and the scour due to floods.
It was observed that the raft was showing signs of cracks between pier and cut off walls. The arrangement was, therefore, subsequently changed by resting pier on raft over the cut off walls.
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Raft foundation is, however, not recommended when
- Spans more that 10m raft being uneconomical.
- Bridge foundation that cannot be inspected during its service life.
- Serious problem of dewatering due to large in flow of water/standing water.
- Where open foundations are feasible.
In other cases of small span bridges on weak soils, the raft foundations may be a most practicable solution.
Well Foundations
Some important points to be noted regarding well foundations are as follows –
a. If the external diameter of single circular wells exceeds 12 m relevant provisions of clause 708.1.2 of IRC: 78-2000 shall apply.
b. The steining thickness of well shall not be less than 500 mm and shall satisfy the following relationship
h = kd L where h = minimum thickness of steining in m d = external diameter of circular well in m
L = depth of wells in m below top of well cap or LWL whichever is more
K = constant(for wells in cement concrete 0.03,brick masonry 0.05 and twin D wells 0.39(For details refer to clause 708.2.3 of IRC: 78-2000).
Piles Foundations
| Type of Strata | Minimum Embedment | |
| Hard rock | 1.5 x dia. of pile | 400 |
| Soft rock | 3.0 x dia. of pile | 250 |
| 2.0 x dia. of pile | 200 | |
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Although piles can be designed as end bearing or friction piles, only end bearing bored cast-in-situ piles drilled with rotary rig be preferred. Designs with single row of piles per substructure and annular piles filled or not filled should not generally be preferred.
3.2 SUB - STRUCTURE
Type designs available would provide sufficient information about the dimensions of the P.C.C. piers and abutments up to a height of 10m. These type designs available are for non-seismic zones only.
Grade of Concrete as are specified below : For bridges(Length > 60 m) :
| Structural member | Conditions of Exposure | ||
| Moderate | Severe | ||
| P.C.C. | M 25 | M 30 | |
| R.C.C. | M 30 | M 35 | |
| P.S.C. | M 35 | M 40 | |
| For other bridges or Culverts (<60m) : | |||
| P.C.C. | M 15 | M 20 | |
| R.C.C. | M 20 | M 25 | |
The proposed allowable compressive, tensile and shear stresses are as follows:
(i) Flexural compression scb = 0.33 fck for all grades of concret
(ii) Flexural tension stb = 0.033 fck for all grades of concrete
(iii) Shear = As below
(a) The allowable shear stress for R.C.C. members subject to flexure, shear
and members subject to axial compression, the allowable shear stress carried by
the concrete (tc) shall be as per following table.
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| 100 A | Permissible Shear Stress in Concrete, t 14/mm2 | ||||
| bd | Grade of Concrete | ||||
| M 20 | M 25 | M 30 | M 35 | M 40 and above | |
| (1) | (2) | (3) | (4) | (5) | (6) |
| 0.15 | 0.18 | 0.19 | 0.20 | 0.20 | 0.20 |
| 0.25 | 0.22 | 0.23. | 0.23. | 0.23. | 0.23. |
| 0.50 | 0.30 | 0.31 | 0.31 | 0.31 | 0.32 |
| 0.75 | 0.35 | 0.36 | 0.37 | 0.37 | 0.38 |
| 1.00 | 0.39 | 0.40 | 0.41 | 0.42 | 0.42 |
| 1.25 | 0.42 | 0.44 | 0.45 | 0.45 | 0.46 |
| 1.50 | 0.45 | 0.46 | 0.48 | 0.49 | 0.49 |
| 1.75 | 0.47 | 0.49 | 0.50 | 0.52 | 0.52 |
| 2.00 | 0.49 | 0.51 | 0.53 | 0.54 | 0.55 |
| 2.25 | 0.51 | 0.53 | 0.55 | 0.56 | 0.57 |
| 2.50 | 0.51 | 0.55 | 0.57 | 0.58 | 0.60 |
| 2.75 | 0.51 | 0.56 | 0.58 | 0.60 | 0.62 |
| 3.00 and above | 0.51 | 0.57 | 0.60 | 0.62 | 0.63 |
For slabs the allowable shear stress carried by concrete shall be Ktc Where K has the values given below
| Overall | depth | of300 or more | 275 | 250 | 225 | 200 | 175 | 150 | or |
| slab (mm) | less | ||||||||
| K | 1.00 | 1.05 | 1.10 | 1.15 | 1.20 | 1.25 | 1.30 | ||
Forces to be considered for stability of piers and abutments are given in IRC:6-2000 Loads & Stresses. The permissible increases in stresses in the various members under different load combinations are also given in the code. The same is summarized as below
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| DING RETURAN | B | |
| ROAD TOP LEVEL | ||
| PIER CAP | ||
| 1 | 1 | |
| n | n | |
| RIDING RETURN | PIER | |
| BB | ||
| FB | ||
| DOWELS | ||
| RCC RAFT | ||
| B | ||
| SECTIONAL ELEVATION ALONG A-A | ||
| ES | CUT OFF | |
| WALL | ||
| Sr. No. | Load Combination | Increase in permissible | ||
| stresses. | ||||
| 1. | Dead + Live | NIL | ||
| 2. | 1 + Secondary + Deformation + Temperature | 15% | ||
| 3. | 2 | + wind + wave pressure | 33 1/3 % | |
| 4. | 2 | + seismic + wave pressure | 50% | |
| 5. | 2 | + barge impact + wind load | 33 1/3 % | |
| 6. | Dead + water current + buoyancy + | 33 1/3 % | ||
| Earth pressure + erection + friction + | 50% | |||
| wind + grade effect 6 + Seismic - Wind | ||||
Apart from above-mentioned combinations, following load combinations should generally be checked.
- Dead + Live + wind in transverse direction Wind acting perpendicular to deck.
65 % perpendicular and 35 % along the deck. The wind velocity and method of computation of forces is given IRC: 6-2000. (Section-II).
- One span dislodged (i.e. smaller span not in position) for pier and no span condition for abutment.
3.3 BEARINGS
3.3.1 Types
Various bearings in use by the department are M.S. plate, cast steel rocker rollers, neoprene, and POT/ PTFE, R.C.C. Roller.
3.32 Selection
The selection of Bearings should be as follows :
1 | Spans upto and including 10 m for solid slab | Tar paper |
| superstructure | ||
2 | Span > 10 m and < 25m | Neoprene |
3 | For larger spans | POT/PTFE |
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Reference should be made toI.R.C.83 Section IX
Part I Metalic Bearings
Part II Elastomeric Berings
Part III POT, POT/PTFE
3.3.3 Seismic arrestors
To prevent dislodgement of superstructure reaction blocks or other types of arrestors shall be provided and designed for twice the seismic force.
3.4 SUPER STRUCTURE
Various types of superstructures are Arches, Masonry, C.C., R.C.C. Girder and deck slab, Solid Slab, R.C.C. T-Beam Slab, R.C.C. Box Beam, Voided Slab, P.S.C. Two Girder, Three Girder, Multi- Girder, Box Girder, Simply supported continuous Cantilever, Balance Cantilever, Hammer Head, Bow string girder, composite construction, cable stayed, suspension.
3.4.1 Selection of Proper Superstructure
Generally the following criteria should be followed for selection of superstructure depending on span length.
- Spans upto 10m. R.C.C. solid slab.
- Spans- 10 to 15m R.C.C. solid slab /Ribbed slab,
- Spans - 15m.to 20m R.C.C. Multi-girder slab system.
- Spans - 20m.to 30m P.S.C. Girder/Box type superstructure.
- Span - 30m to 60m P.S.C. Box girder.
For spans more than 60 m the discussions should be held with Superintending Engineer, Designs Circle regarding selection of the type of superstructure.
For spans up to 10m solid slab superstructures are found most suitable. As the span increases beyond 10m the thickness of solid slab poses difficulties during concreting. Lot of construction joints are created in the structure if proper programme of concreting is not prepared and insisted upon.
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Spans between 15m to 20m, multi-girder system would be desirable. Two-girder system should be avoided as far as possible. In case of single lane bridges two-girder system is natural choice.
For spans between 20m and 30m R.C.C. box type superstructure is considered suitable. Use of R.C.C. girder and slab system might result in excessive deflections under live load. Box girder is a more desirable shape for the superstructure.
Beyond 30 m span, it is necessary to go for P.S.C. This enables us to somewhat restrict the deck height to the desired level. For spans greater than 60m discussions should be held with Superintending Engineer, Designs Circle for deciding the type of superstructure.
3.4.2 Type Design
Type designs are available for solid slab and girder type superstructures. The type designs prepared by M.O.S.T. are also available for R.C.C. solid slab up to 10 m, R.C.C. Girder slabs upto 24 m and P.S.C. girder slab bridges upto 40 m spans.
3.4.3 Minimum thickness
Minimum thickness of deck slab shall not be less than 300 mm and 200 mm at tip of cantilever in transverse direction and minimum thickness of soffit slab shall be 240mm irrespective of provisions elsewhere. All the specified minimum thickness are from durability point of view.
3.4.4 Expansion Joints
To cater for the expansion and contraction of superstructure suitable expansion joint is required to be provided. The expansion joint is also supposed to be leak proof so that the superstructure, bearings and piers do not get damaged due to such leakage of rainwater etc.
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SUITABILITY CRITERIA FOR ADOPTION OF DIFFERENT TYPES
OF EXPANSION JOINTS
| Sr. | Type of | Suitable for adoption joint | Service | Special Consideration | |
| No | Expansion | Life | |||
| 1 | Buried | Simply supported | 10 years | Only for decks | |
| . | spans up to 10m | With bituminous | |||
| asphaltic wearing | |||||
| coat. | |||||
| 2 | Filler Joint | Fixed end of simply | 10 years | The sealant and joint | |
| . | supported spans with | filler would need | |||
| In-significant movement. | replacement if found | ||||
| damaged. | |||||
| 3 | Asphaltic | Simply supported spans | 10 years | Only for decks with | |
| . | Plug Joint | for right or skew upto | bituminous /asphaltic | ||
| (20 degree) moderately | wearing coat. Not | ||||
| curved or wide deck | suitable for bridge with | ||||
| with maxi- mum | longitudinal gradient | ||||
| horizontal movement | more than 2% and | ||||
| not exceeding 25mm. | cross camber/super- | ||||
| elevation exceeding | |||||
| 3%. | |||||
| 4 | Compression | Simply support of | 10 years | Chloroprene/ closed | |
| . | Seal Joint | continuous spans right or | Foam Seal may need | ||
| skew (upto 30°), | replacement during | ||||
| moderately curved with | service. | ||||
| maximum horizontal | |||||
| movement not exceeding | |||||
| 40 mm. | |||||
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| 5 | Elastomeric | Simply supported or | 10 years | Not suitable for | |
| . | slab seal joint | continuous spans Right or | bridges located in | ||
| skew (less than 70 degree) | heavy rainfall area and | ||||
| moderately curved with | spans resting on | ||||
| maximum horizontal | yielding support. | ||||
| movement up to 50 mm. | |||||
| 6 | Simple strip | Moderate to large simply | 25 years | Elastomeric seal may | |
| . | seal joint | supported.(cantilever/ | need replacement | ||
| continuous construction | during service. | ||||
| having right, skew or | |||||
| curved deck with | |||||
| maximum horizontal | |||||
| movement upto 70 mm. | |||||
| 7 | Modular strip/ | Large to very large | 25 years | Elastomeric seal may | |
| . | Box Seal | continuous/cantilever | need replacement | ||
| Joint | construction with right, skew | during service | |||
| or curved deck having | |||||
| maximum horizontal | |||||
| movement in excess | |||||
| of 70 mm. | |||||
| 8 | Special | For bridge having wide | 25 years | Elastometric seal may | |
| . | joints for | decks/span length of | need replacement during | ||
| special | more than 120 m. or/and | service. Provision of | |||
| condition | involving complex | these joints may be | |||
| movement/rotations in | made with prior approval | ||||
| different directions/ | of competent authority. | ||||
| plans, provision of special | |||||
| type of modular expansion | |||||
| joints such as swivel joists | |||||
| joints may be made. | |||||
These are proprietary items for which 10 years warranty shall be insisted upon from the suppliers.
For larger expansion gaps, of about 50mm and more the joint has to be designed suitably. Other types of joints are :
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- Finger type joint (Cast steel).
- Strip seal joint (Elastomeric)
- Compression seal joint (Elastomeric)
- Slab seal joint (Elastomeric)
- Modular joints. (Modules with Elastomeric)
The above joints are costly as compared to conventional joint described earlier. We are, however, left with no choice for long span bridges but for adopting them. For details of material properties refer latest M.O.S.T. specifications for Roads and Bridges.
The above item are presently patented and hence detailed design calculations are not generally made available. It should be insisted upon.
For details of these joints refer literature given by the manufacturers.
Extra care need be taken for maintaining line and level of the joint to match perfectly with the geometry of the deck surface. Expansion joint is the place wherein lies the comfort of the road users. Improper fixing invites criticism from public.
3.4.5 PARAPET AND KERB
Deciding the type of railing, kerb etc., as per the type of bridge i.e. high level or submersible.
(i)For High Level Bridge
Superintending Engineer Designs Circle’s Type drawings or Sanchi Type parapet as mentioned in designs criteria can also be adopted.
(ii) For Submersible Bridge
Railing shall be removable type. Either pipe railing or collapsible type as shown in the type drawings.
3.4.6 WEARING COAT
Earlier upto 1980 R.C.C. wearing coat was generally adopted. Now as per Govt. in P.W.D. Circular No.CEC/1179/50677/CR-225/D-29-A dated 12.08.80, following type of wearing coat are generally provided for bridges.
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Conventional Practice
High Level Bridges : Bituminous 50 mm DBM + 25 mm AC/SDBC
Submersible Bridges : C.C. M-20 with temperature steel.
Long Span Bridges : Bituminous.
Better treatment considered today is –
12 mm Mastic Asphalt as leak proof layer.
+ 50 mm DBM
+ 25 mm Bituminous concrete / Mastic Asphalt
3.4.8 WATER SPOUTS
Waterspouts are required to drain out the rainwater from the deck surface quickly. The deck has camber or super elevation, which help rainwater get quickly towards kerbs. The waterspouts located near the kerb further disposes the water out. One water spout per 20 sq.m. of the deck area is considered adequate.
- 4. DESIGNING
4.1 DESIGN LOADS & STRESSES
All new structures shall be designed for the condition when footpath is used as carriageway. The footpath portion may be provided at the same level as the bridge carriageway and separated by crash barrier in non built-up areas. In built-up areas, raised footpaths shall be provided.
All the components of structures shall be designed for a service life of 100 years except appurtenances like crash barriers, wearing surface and rubberized components in expansion joints and elastomeric bearings. All the requirements to achieve durability and serviceability shall be implemented.
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4.2 HYDROLOGY
All the structures shall have adequate waterway, which shall in any case be not less than that of existing bridge (except when such waterways can be reduced in cases like clogging or silting of spans, etc.). The design discharge shall be evaluated for flood of 100-year return period.
4.3 SUB-SOIL INVESTIGATION
Independent sub-soil investigations shall be carried out to establish the soil parameters required for detailed design of foundations in accordance with relevant provisions of IRC:78 and MORTH Specifications.
4.4 TEMPORARY WORKS
4.4.1 Form Work
The Concessionaire shall be responsible for the safe, workable design and methodology for all temporary or permanent forms, staging and centering required for supporting and forming the concrete of shape, dimensions and surface finish as shown on the drawings (Refer IRC:87). Adequate foundation for the staging shall be ensured. Redundancy in support system shall also be ensured by providing diagonals and additional members.
The following guidelines shall be adopted:
(i) Formwork shall be of steel, marine ply or laminated plywood.
(ii) Only such shuttering oil (release agent) shall be used, which permits easy removal of shutters without leaving stains or other marks on the surface of the concrete. Requirements given under Clause 3.5 of IRC:87 shall also be complied with.
(iii) In case of tubular staging of heights more than 10 m, special attention shall be paid to the structural adequacy of the system, efficacy of the connections (clamps etc), and foundations. Foundation blocks of adequate thickness in M15 cement concrete shall be provided under the base plates to prevent differential settlements.
(iv) In case of prestressed concrete members, the side forms shall be removed as early as possible and the soffit forms shall permit movement of member without restraint, when prestress is applied.
(v) Adequate foundations for formwork shall be ensured.
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4.4.2 Special Temporary and Enabling Works
Designs, drawings and methodology proposed by the Concessionaire in the use of special temporary and enabling works like Launching Girders, Cantilever Construction Equipment, Tall Formwork, Shoring for Earth Retention, Lifting and Handling Equipments and the like shall be submitted to the Independent Engineer (IE) for his review and comments if any. The Concessionaire shall be fully responsible for the design and structural adequacy of all temporary and enabling works. Review by IE shall not relieve the Concessionaire of this responsibility.
4.5 DESIGN
4.5.1 Foundations and Sub-structures
The design of foundations and sub-structures shall conform to IRC:78.
Open Foundations
The design of open foundations shall conform to IRC:78. Floor protection shall be provided as per Section 2500 of MORTH Specifications.
Pile Foundations
(i) The design of pile foundations shall be done as per IRC:78. The Concessionaire shall submit a method statement supported by the following:
(a) Bore-log details for each foundation;
(b) Design assumptions;
(c) Design calculations both for single pile or group of piles and for pile type;
(d) Type of piles-Bored cast-in-situ piles and driven piles;
(e) Procedure adopted for installation of piles;
(f) Arrangements for load testing of piles;
(g) Format for reporting of test results.
(ii) The Concessionaire shall submit the following information regarding proposed proprietary system of piling:
(a) General features of the process/system along with specifications and standards.
(b) Authenticated copies of license/agreement, if any;
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(c) Details of plant and equipment to be used along with the names of manufacturers and name of process/system;
(d) Details of projects where the process/system has been successfully used;
(e) Limitations, if any;
(f) Acceptance tests and criteria;
(g) Installation and maintenance procedure and schedule; and
(h) Performance warranty.
Well Foundations
(i) For conventional method of well sinking, the Concessionaire shall submit a method statement including the following:
(a) Design calculations and drawings,
(b) Procedure for sinking and plugging of well,
(c) Format for reporting of test results.
(ii) If proprietary system of well sinking like jack down method is proposed to be used, the Concessionaire shall submit relevant information covering inter-alia the following:
(a) General features of the system along with specifications and standards and justification for the thickness of steining proposed to be adopted;
(b) Authenticated copies of license/agreement, if any;
(c) Details of plant and equipment to be used along with the names of manufacturers and name of process/system;
(d) Details of projects where the process/system has been successfully used;
(e) Limitations, if any;
(f) Acceptance tests and criteria;
(g) Installation and maintenance procedure and schedule; and
(h) Performance warranty.
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(iii) The Concessionaire in his Methods Statement shall include the procedure for sinking by special methods, carrying out tests, if any, of wells including design criteria/calculations, drawings and formats for reporting test results.
4.5.2 Approach Slabs
Approach slabs shall be provided as per Clause 217 of IRC:6 and Section 2700 of MORTH Specifications.
4.5.3 Superstructures
The design of reinforced and pre-stressed concrete superstructures shall be as per IRC:21 and IRC:18 respectively. The design of steel and steel-concrete composite super structures shall conform to IRC:24 and IRC:22 respectively.
The Concessionaire shall submit Method Statement indicating inter-alia the following:
(i) Sources of materials,
(ii) Design, erection and removal of formwork,
(iii) Layout of casting yard together with necessary details,
(iv) Production, transportation, laying, compacting and curing of concrete,
(v) Sequence of concreting in cast-in-situ construction, side shifting of girders, if applicable and placing of girders on the bearings,
(vi) Details of construction joints,
(vii) Prestressing system, if required,
(viii) Methodology and equipment for side shifting and launching of pre-cast girders,
(ix) Key personnel for execution and supervision,
(x) Testing and sampling procedure,
(xi) Equipment details.
4.6 Reinforced Earth Retaining Structures
Reinforced earth retaining structures shall not be provided for height more than 6 m unless otherwise specified, and near water bodies. Such structures should be given special attention in design, construction, ground improvement where necessary,
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maintenance and selection of System/System design. Local and global stability of the structure shall be ensured.
Design Accreditation and warranty for life of the structure from the approved supplier/ manufacturer shall be obtained and furnished. A qualified and experienced technical representative of the approved supplier/manufacturer shall be present on site throughout during the casting and erection phases to ensure that the quality of the works executed by the Concessionaire is in accordance with good industry practice.
The Concessionaire shall submit relevant information on the system covering inter-alia the following:
(i) General features of the system along with specifications and standards;
(ii) Authenticated copies of license/agreement, if any;
(iii) Details of plant and equipment to be used along with the names of manufacturers and name of process/system;
(iv) Details of projects where the process/system has been successfully used;
(v) Limitations, if any;
(vi) Acceptance tests and criteria;
(vii) Installation and maintenance procedure and schedule; and
(viii) Performance warranty.
The Concessionaire shall submit a method statement including the following:
(i) Design assumptions, calculations and drawings,
(ii) Construction Procedure,
(iii) Tests to be conducted including frequency and the formats for reporting the test results.
The packaging of reinforcing elements shall clearly indicate the name of the manufacturer/ supplier and brand name, date of production, expiry, if any and batch identification number along with the manufacturer’s test certificates.
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4.7 Safety Barriers
(i) For bridges without foot paths, concrete crash barriers shall be provided at the edge of the carriageway on all new bridges.
(ii) The type design for the crash barriers may be adopted as per IRC:5. The design loading for the crash barriers shall be as per Clause 209.7 of IRC:6.
(iii) For bridges with foot paths, pedestrian railing shall be provided on the outer side of footpath.
(iv) The railings of existing bridges shall be replaced by crash barriers, where specified in Schedule-B of the Concession Agreement.
(v) Parapets/Railings of the existing bridges/culverts to be repaired/replaced shall be specified in Schedule-B of the Concession Agreement.
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