Bar Bending Schedule for Reinforced Concrete Beam

Bar bending schedule provides the reinforcement calculation for reinforced concrete beam. It provides details of reinforcement cutting length, type of bends and bend length.

We will take one example for reinforcement quantity calculations for a concrete beam.

Bar Bending Schedule for Reinforced Concrete Beam

Example of Beam Reinforcement Calculation:

Consider a beam of clear length of 4m, 300mm wide by 450mm depth. It consists of 2-12 diameter bars at top, and 2-16 diameter and 1 – 12 diameter bars at the bottom. Diameter of stirrup is 8mm spaced at 180mm center to center. Clear cover to reinforcement provided is 40mm.

Fig: RCC Beam Reinforcement Details

Fig: RCC Beam Cross-Section

Now we will calculate the length of reinforcement based on shapes of reinforcement required for reinforced concrete beam in above example.

We will start with bottom reinforcement, B1.

Bar shape of B1 is as shown below:

Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length

Bend length = 6 x 16 = 96 consider as 100mm

Bend length is calculated as 6 x diameter of bar for reinforcement conforming to IS: 1786-1961

Length of B1 = 4000 + 2 x 230 – 2 x 40 + 2 x100 = 4580mm

Length of bar B2 is calculated based on shape of this bar. This bar bends up near the support as shown below:

Length of bar B2: A + B + C = 4000 + 2 x 230 – 2 x 40 + (1.414xH – H)

H = 450 – 2 x 40 – 2 x 12 – 2 x 12/2 = 334mm

B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 4518.3 = 4520mm

Length of Bar T1 = 4000 + 2 x 230 -2 x 40 = 4380mm

Length of Stirrups S1:

Stirrups are spaced at 180mm center to center. Stirrups are provided between walls or support for a beam.

No. of stirrups required for given beam =

  

Length a = 450 – 2 x40 – 8 = 362mm

Length b = 300 – 2 x 40 – 8 = 212mm

Therefore, length of 1 stirrup S1 = 2 x (212 + 362 + 90) = 1328 mm

Where 90mm is the minimum hook length as per IS 2502 – Table – II

Bar Bending Schedule for RCC Beam:

No.	Bar Mark	Bar dia (mm)	No. of bars	Length (mm)	Weight of bars (kg)	Bar Shape
1	B1	16	2	4580	14.5
2	B2	12	1	4520	4.02
3	T1	12	2	4380	7.80
4	S1	8	24	1330	12.6

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What Is A Bar Bending Schedule

Bar Bending Schedule or BBS is actually a detailed tabulated worksheet showing the particulars of reinforcing bars as needed in reinforcement drawings of a structure. The phrase “Bar Bending” is so because at the steel yard where different types of reinforcement are cut and bent this table is used as a reference to bend the reinforcement bars in desired and required shape and sizes.

What information a bar bending schedule has?

Bar Bending Schedule is expected to contain all the important information and summarizes in tabular form. A good bar bending schedule must contain the following information :-

1. Bar Mark No.
2. Cut Length
3. No. of Pieces
4. Bar Cut Shape
5. Bar Diameter

To know more about each of the above information, how to calculate and what it should be please follow this link

What Information A Bar Bending Schedule Should Contain.?

Therefore now we are able to prepare a Template of a bar bending schedule; a typical bar bending schedule would be like this :-

A Typical Bar Bending Schedule Table

Now from here you might be asking one question that what actually is the need of this tedious job of preparing Bar Bending Schedule.

What is the need of Bar Bending Schedule?

The simplest answer for this question would be that money matters a lot and reinforcement bars, in any project, takes a healthy share of the financial term of the project. Therefore in order to purchase material we need an estimate which should be near-to-actual during execution, this estimate may differs from engineer estimate which is only on the basis of experience and is only taking construction or bidding tender drawings as reference which are general and typical.

Thus with the help of Bar Bending Schedule you would have a clear figure about how much reinforcement you need to purchase of various diameters. After purchase the reinforcement the next phase is to cut and bend.

This cutting and bending must follow the bar shape shown in the bar bending schedule, thus before execution bar bending schedule is a must-to-have document at site. It is a good working technique because we cannot bear any error or mistake during this cutting and bending which otherwise will cause financial problems for all concerned.

The next phase after project execution is witness of the quantity by engineer at site as per drawings and verification of this quantity for further payment and financial steps. Engineer during steel fixing check the rebar as per the shop drawing and ensure it matches the bar bending schedule duly approved by the quantity and measurement engineer.

Thus for the payment of the contractor by client this document is also needed.
The contractor actually submits a document called Quantity Witness Report (QWR) to the engineer having attached all the documents required like, reinforcement approved inspection requests, approved structural shop drawings, approved bar bending schedules. This is then verified by the engineer.

What are the qualities of a good bar bending schedule?

It is always ensured that the person preparing the bar bending schedule must have a solid site execution experience. The rebar designation and cut length must be carefully selected as it will be the defining point for the scrap which will be remained after cutting and bending

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What Information A Bar Bending Schedule Should Contain.?

Bar Bending Schedule or BBS is actually a detailed tabulated worksheet showing the particulars of reinforcing bars as needed in reinforcement drawings of a structure. The phrase “Bar Bending” is so because at the steel yard where different types of reinforcement are cut and bent this table is used as a reference to bend the reinforcement bars in desired and required shape and sizes.

Bar Bending Schedule summarizes and should contain the following information :-

1. Bar Mark No.

In Contractual practice of construction projects, the designed made by consultants termed as the Engineers are issued as Construction Drawings by a covering letter termed as Drawing Transmittal Slip (DTS). These construction drawings are typical drawings only showing the criteria of design and requirement as per the standards of design and detailing.

Keeping in view of these construction drawings, contractor prepares his own shop drawings showing detailed sketches and sections as needed by the structure and as desired by the engineer. These shop drawings are submitted for review and approval of engineer which must be approved prior to the execution of work at site.

The structural drawings showing reinforcement in construction drawing only annotate the diameter and spacing along with orientation and occasionally quantity but not too often.

The structural shop drawings on the other hand show the quantity, orientation, Bar designation also known as Bar Mark No. or Bar Annotation No. It is a unique designation of the reinforcement bar which is noted at the end in Bar Bending Schedule.

The two reinforcing bars must be given different designation no. if the bar length is changing or if the bar shape is changing.

2. Cut Length

It is the nominal length as per the requirement of the structure and construction drawing, usually noted in mm. The cut length may or may not contain the bending length which is the extra length needed to bend a large diameter rebar at angle of 30, 45 or 90 depending on requirement. If the bending length is contained in it than during verification of this BBS by consultant they prepare bend deduction sheet and will deduct the bend as it is not payable in most of the circumstances.

3. No. of Pieces

Bar Bending schedule also provide the quantity and number of pieces of each designated bar. It is calculated by dividing the space / structural dimensions by the spacing as required by the design. For example if the length / span of beam is 6000 mm and it has shear ties at spacing of 300 mm center to center i.e. c/c than the quantity or no. of pieces would be 6000 / 300 = 20 nos.

4. Bar Cut Shape

It is the most important column in the Bar bending schedule as far as the bending and cutting of reinforcement is concerned at site. Each bar no. can have different shape depending on the shape of the structure to be reinforced. Thus the bar may have a hook or a bend in any angle which must be properly mentioned. If the bar is provided with a curve than a clear figure showing radius of curvature must be given. Similarly if the reinforcing bar is confined in a sloping portion and the bar is required to have a varying length than a delta is calculated showing the unit increment or decrement of rebar length and must be shown in the bar bending schedule (will be explained later on).

5. Bar Diameter

Each bar No. is shown with a diameter of rebar usually in mega projects the diameter used is of #4, #6, #8 or #10 & #11. Small diameter rebar is used in construction joints or as temperature reinforcement and larger diameter bars are main reinforcement bars.

Each Bar Diameter have a nominal corresponding unit weight which is used at the end of the bar bending schedule showing the weight of each category of bar diameter.

Table showing Each Bar Diameter corresponding to No. and Nominal Unit Weight

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Landings in Stairs – Purpose, Location and Standard Dimensions

What is a Stair Landing?

Landings in a stair is a level floor or platform constructed at a location where the direction of stairs changes, between flights of the stair, or at the top of stair flight.

The locations of landings in a stair is shown in Figure 1, Figure 2 and Figure 3.

Fig.1: Landing is provided between flights of a stair

Fig.2: Stair landing at the top between and bottom of stair flights

Fig.3: Landing is provided when the direction of stair changes

What is the Purpose of Stair Landing?

•  Stair landing is provided to permits stairs to change directions, Figure 4.
•  Another purpose of stair landing provision is to allow occupants to rest.

Fig.4: Landing provided to allow stairway to change its direction

What are the cases in which stair landings are needed?

•  Stair landing should be provided at the top and bottom of each flight of exterior and interior stairs.
•  Stair landing is needed where a doorway at the top of stair flight swings toward the stair, Figure 5 and Figure 6.

Fig.5: Doorway swing on landing of stairway

Fig.6: Doorway opens on toward the stairway

•  For stairways with straight run that have an overall rise greater than 3.65m, an intermediate landing should be provided.

What the cases in which stair landing can be omitted?

•  If a doorway that located at the top of a stair in a dwelling unit is swing away from the stair, then landing is not required between the stair and the door.
•  It is possible to omit landing at the top of a stair serving a secondary entrance to a single dwelling unit provided that the stair does not have more than three rises and the door is sliding or swing away from the stair.
•  Landing stair can be neglected at the bottom of an exterior stair provided that there are no obstruction within a lesser of stair width or 900mm for stair serving single unit and 1100mm for stair not serving a single dwelling unit.

What are the standard dimensions of stair landing?

 The width of landing should not be smaller than the width of stairway they serve as illustrated in Figure 7.

Fig.7: Width of landing determined based on the stairway they serve

•  The dimension of landing in the direction of travelling should be at least equal to the width of the stair and it should not surpass 1219mm where the stairway is a straight run.
•  When a door is opened on the landing, it should not reduce the landing smaller than half of required width. Added to that, when the door is opened completely, it should not project greater than 178mm on the landing.
•  If wheelchair spaces are required on stairway landing, it should not be located with the required dimension of the landing and doors must not swing over the wheelchair space.

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