01-BRIDGES



BRIDGES

I.SITE SURVEY:

Site survey should be furnished as per check slip for Bridges as prescribed by the department.

a)Report accompanying the Site survey along with HPs of canal with road details.(As per approved HPs.)

b)Site plan along with flow direction of canal, road way  angle and direction of skew if any,net levels @10 M intervals and also covering the approaches to a sufficient distance not less than 1/4 km on either side (IS : 7784 (Part I)

c) LS of canal as per approved HPs    ii) L.S of Road Covering 500 metres on U/S & D/S with levels @ 10m intervals.

d)Important details of road bridge and type of road bridge with carriage way width.

e)Bore hole data / TPs upto Hard strata or for min. depth of 2m for shallow foundations & upto 1/3rd embedment depth below maximum scour depth along the Centre Line @ suitable intervals depending upon the importance of the structure with minimmum 3 Nos covering Canal @ centre, right and left sides.Also the safe bearing capacity of foundation strata be furnished.(IRC78:2000).

2.DESIGN :

a)HYDRAULIC DESIGN :

1)Design of ventway(IRC: 5 -1998 )

2)The bridge  crust level shall be either natural GL or existing road crust level which ever is higher

3)Afflux calculations by Molesworth's formula (Max-50mm) (IRC: 5 -1998)

h =   [v2 / 17.85 + 0.0152]    [A2/ a2 -1 ]   

4)Scour depth calculations (IRC: 5 -1998 )

R =  1.34  [ q2 /f1/3] 

b)STRUCTURAL DESIGN :

SUPER STRUCTURE

a)Design of Deck slab / Girder (IRC: 6-2000 IRC: 21-2000 For DLRB and Girder bridges adopt MOST drgs / plates)

SUB STRUCTURE

1Piers: Minimum Thickness of Pier shall be 1m. (IRC: 6 - 2000 )

2.Abutments,Wings /  Returns be designed adopting TVA procedure/Coulomb's theory/Rankine's theory adopting top width of 500 mm. (IRC: 78-2000,TVA Hand book, )(IRC:40-1995 )

3.Bed blocks in RCC M20 grade (minimum)  (IRC :21-2000)

4.Type of foundation based on foundation strata available -open/ Raft / Piles (IRC: 78-2000 )

5.Unless otherwise metioned, the following minimum grades of Concrete are recommended(IRC: 21-2000)

i) RCC - M 20 Grade

ii) For DLRB RCC Deck / Girder - M25 Grade

iii) CC - M 15 Grade

iv) Levelling course - CC M 10 Grade

6.Protection works on either side of Bridge

100 mm thick CC lining in M10 grade for bed & sides shall be proposed & for a minimum length of 10m on either side of the structure.            

c)MISCELLANEOUS ITEMS :-

Approach slab & approaches RCC Kerbs (IRC: 5-1998 and MOST Drgs)

Railling(MOST Drgs )

Expansion joints, Constructon & Contraction Joints Drainage spouts(MOST Drgs)

Wearing coat (Next higher grade than Deck slab ) Ornamental pillaster(MOST Drgs )

OMAMENTAL PILLASTER(MOST Drgs )

Guide posts or parapets (MOST Drgs )

Design of bearings (IRC: 5-1998,IRC:83 Part-I & II)

3.DRAWINGS

1)General Layout on net level plan duly showing contours.General Plan, Sectional Elevation & End View - Plan indicating Half plan @Top & Half plan @ bottom &  Sectional elevation along the LS  & End view  along the cross section. (Scale : 1:50, 1:100, (or) 1:200)

2)Sections of Piers, Abutments, Wings & Returns RCC Slab,Girder details (Scale 1:50 )

3)Miscellanious details viz duct wall, railings, drainage spouts,bed blocks,bearings etc.,(Scale 1:50 (or) 1: 25 (or)  1: 10 )

4)The Drawings shall contain assumptions made,TPs, specifications(Scale 1: 20 (or) 1: 1)

5)HPs of Canal, Bar bending schedule, stress table etc.

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