BBS ( Bar Bending Schedule)

 

BBS ( BAR BENDING SCHEDULE)

Q1 What is Bar Bending Schedule?

   Bar Bending Schedule is cut & bending of reinforcement bar into the required shape and making its list which describes.

• Location & marking of bar
• Type of bar 
• Size of bar
• Cutting the length of the bar
• Number of bars 
• Bending details of bar
• Total Quantity

For each bar in reinforcement drawing of a structure, This process of listing is called SCHEDULING

Advantages of Bar Bending Schedule

• Cutting length & Bending of reinforcement can be done
• BBS avoids wastage of steel reinforcement & thus saves project cost.
• It provides a better Estimation of Reinforcement steel requirements for each & every structure member.
• B.B.S. is very much useful during Auditing of Reinforcement & provides checks for theft & pilferage.
• It enables easy and fast preparation of Bills of construction work fro clients & contractors.

Why Steel Is Used As Reinforcement Bar?

• coefficient of Thermal Expansion characteristics similar to concrete.
• Good strength for the economic design of R.C.C. structure.
• Good gripping or good bonding with concrete.
• Good resistance against corrosion for higher durability
• Good bendability for providing the required shape.

Type of Reinforcement Bar

Fe-250

It is a plane steel bar with a smooth surface not making good bonding with the concrete

Fe-415

In this bar, rib around its surface for good bonding with the concrete

Fe-500

In this bar, Rib and lugs both are provided for good bonding with the concrete.

Size & Unit Weight of Bar

Dia. of Bar                            Unit Weight of Bar (D^2/162)

8 mm                                    (8x8)/162=0.395    kg/m

10 mm                                  (10x10)/162= 0.617  kg/m

12 mm                                  (12x12)/162=0.889   kg/m

16 mm                                  (16x16)/162=1.580   kg/m

20 mm                                  (20x20)/162=2.470   kg/m

22 mm                                  (22x22)/162=2.987   kg/m

25 mm                                  (25x25)/162=3.858   kg/m

32 mm                                  (32x32)/162=6.320   kg/m

Bend Deduction & Values

Bend increases the length of the bar so we need a lesser length than we see in the drawing. So cutting length is taken lesser than the required length.

• 45° Bend - Bend deduction 1D
• 90° Bend - Bend deduction 2D
• 135° Bend - Bend deduction 3D
• 180° Bend - Bend deduction 4D

Clear Cover & Effective Cover

Clear Cover - The distance between the outer face of the column, beam to the outer face of the stirrup bar

Effective Cover - The distance between the center of the main bar to the outer face of the column & beam

Values of Clear Cover

FOOTING                      50 mm

COLUMN                      40 mm

BEAM                            25 mm

SLAB                             20 mm

STAIRCASE                  15 mm

CHHAJJA                      15 mm

PILE                               60 mm

PILE CAP                      60 mm