What is Bar Bending Schedule (BBS) in Construction?

In reinforcement detailing of concrete, it is very important to keep an order in which a bar is fixed. The bars that are used are numbered appropriately as per the placement in the drawings and the schedules kept.

Different bar bending schedule format can be followed by the construction industry. The British standard schedules and Indian standards are explained below. The Indian standard codes use Other detailed formats for bar schedules.

What is Bar Bending Schedules?

Bar Bending schedule or bar schedule or bending schedule can be defined as a list that is used to enlist the bars that are used for the reinforcement of the concrete which is planned and decided based on standard codes. The Table-1 shows the bar bending` schedule as per British Standards.

Table.1: BAR BENDING SCHEDULE

For each structural element or a member, a separate schedule has to be prepared which is done corresponding to its detailed drawing. The table-2 shows an example of filled bar schedule. For multi stored building, the bars that are required is scheduled floor by floor.

In the table-1 and 2,

Column 1: This column is the structural element for which the bar schedules have to be prepared. It can be a base, column, beam etc. It is customary to start the schedule with foundation and progress in the way how the building construction is carried out. The same column also asks for the number of members of the similar type that will make up the structure.

TABLE.2: BAR BENDING SCHEDULE EXAMPLE

Column 2: In column 2, the first title is reinforcement, which will ask the physical dimensions of the reinforcement to make the fabricator know the extent of cutting and bending required. The Number of bars in each will refer to the number of similar bars of this mark in the specified member. The total number is equal to the product of total similar members and the number of bars in each.

The size of bar diameter in millimeters is specified in column 2 will refer the steel. R is for plain round mild steel bars that have the strength of 250MPa, Y is the high yield deformed steel bars with the strength of 450MPa and Z is for those type of steel not covered under R or Y type.

Mark in column 2 will refer to the bar mark i.e. the serial number that is allocated in the detailed drawing. They are listed in mark order, this is the order in which they will be assembled in the formwork.

The length requirement in column 2 is obtained only when the bending dimensions are obtained.

Column 3: The third column will ask for Bending Dimensions. This is obtained based on the bending details of the reinforcement. The British code BS 4449, BS 4482, BS 4483 and BS 6744 have certain standard bending shapes documented and called as shape codes. These shape codes are the basis of which the third column is filled. Some of the examples of shape codes are given below.

Table.3: Bar Shape Code As per British Standards

The shape codes will be defined by two digit numbers. The first column will give the number of the shape code. The method of measurement of bending dimensions is given in the second column. The third column will give the total length of the center line. The sketch and dimensions are given in the last column, which is as per the schedule.

Requirements for Preparing the Bar Bending Schedule

As mentioned before, different countries follow different standards for concrete design. This will hence have different bar bending schedule format. But whatever be the standards followed, there are some standard requirements that are to determined to fill up the bar schedule. This will include:

1. Bar Number or Bar Mark Reference
2. The Bar Shape - Shape Code
3. Diameter of the Bar
4. Spacing
5. Length of the Bar
6. Cutting Length of the Bar
7. Number of Bars Used Per Member

 
These needful categories are provided as columns in the bar bending schedule.

Need For Bar Bending Schedules

The detailer will prepare the schedule and the builder will use the schedule for practical implementation. These details are used for the procurement of materials. The schedule is the basis on which quotes and rates are obtained from the reinforcement supplier, the steel fixer and the clerk of works and the quantity surveyor.

All these objectives will make it necessary for a bar bending schedule to be completely documented by all means. The terms 'bar schedule' is given for this documentation and fabricator will mostly prepare separate cutting and bending lists for his own purpose and convenience.

As we got to know that the bar bending schedule is prepared in a sequential order from the foundation to the roof. The cutting and the bending details will be sorted into the type and the size of the bar.

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