Bar Bending Schedule for Foundations, Columns, Beams and Slabs

Bar bending schedule is an important structural working document that rightly gives the disposition, bending shape, and total length of all the reinforcements that have been provided in the structural drawing, including the quantity. It is the bar mark from structural detailing drawing that is transferred to the bar bending schedule. We normally quantify reinforcements based on their unit mass.

The unit mass of the reinforcements are derived from the density of steel. The density of steel normally adopted for this purpose is 7850 kg/m³.

Lets take a look at 12mm bar, the area of steel of steel is given by

πd²/4 = π×12²/4 = 113.097mm² = 0.0001131m²

Considering a unit length of the bar, we can verify that the volume is 0.0001131m³

Knowing full well that Density = Mass/Volume

7850 = Mass/0.0001131

Therefore, the unit mass of 12mm Bar = 7850 × 0.0001131 = 0.888 kg/m

Weight per metre = 0.006165×(dia. Of bar)² {kg}

8mm = 0.395kg/m

10mm = 0.616kg/m

12mm = 0.888kg/m

16mm = 1.579kg/m

20mm = 2.466kg/m

25mm = 3.856kg/m

32mm = 6.313kg/m

40mm = 9.864kg/m

There are some basic standard shapes that have definite shape codes. But in modern bending schedule, shape codes are rarely included. However, the real shape of the member is drawn out for the fitters (iron benders) to follow.

To obtain the length of reinforcement bars, use the following relation;

Length of bar = Effective Length + Width of Support – Concrete cover (s) – Tolerances (say 10mm)

Reinforced concrete is the most commonly used structural material in engineering construction. Although concrete is strong in resisting compressive stress, it is weak intention. Hence to withstand tensional stresses, steel is need in concrete. The reinforcement in concrete may be simple bars or rods bend and tied to a given schedule with stirrups. The nominal diameters of bars used on site were Y10, Y12, Y16, Y20, Y25 and Y32 and Y40.

Steel are supplied in two basic types:

• Mild steel (250 N/mm²)
• HYSD steel (460 N/mm²)

Bar Bending Schedule for Foundation

A foundation, especially Pad Foundation always comprises of 3 types of Bar Shapes. When determining the Bar Bending Schedule for Foundation you estimate the amount of Steel require i.e No. of Bar for each member and you must know the total No. of members for each of the bar shapes.

The Diagram Below is an Example of a Bar Bending Schedule for Pad Footings

From the Diagram Above, you can see that the details of the Bar Bending Schedule for Pad Footings of a Building is being Stated. This Schedule help in purchase of the Reinforcements and also help the Iron Bender while Working.

Bar Bending Schedule for Columns

Columns Bar Scheduling also comprises of 3 Bar Shape. When determining the Bar Bending Schedule for Columns you estimate the amount of Steel require i.e No. of Bar for each member and you must know the total No. of members for each of the bar shapes.

The Diagram Below is an Example of a Bar Bending Schedule for Columns

From the Diagram Above, you can see that the details of the Bar Bending Schedule for Columns of a Building is being Stated. This Schedule help in purchase of the Reinforcements and also help the Iron Bender while Working.

Bar Bending Schedule for Beams

When determining the Bar Bending Schedule for Beams you estimate the amount of Steel require i.e No. of Bar for each member and you must know the total No. of members for each of the bar shapes.

The Diagrams Below is an Example of a Bar Bending Schedule for a Floor Beams

From the Diagrams Above, you can see that the details of the Bar Bending Schedule for Floor Beams of a Building is being Stated. This Schedule help in purchase of the Reinforcements and also help the Iron Bender while Working.

Bar Bending Schedule for Slabs

When determining the Bar Bending Schedule for Slabs you estimate the amount of Steel require i.e No. of Bar for each member and you must know the total No. of members for each of the bar shapes.

The Diagrams Below is an Example of a Bar Bending Schedule for the Slab of a Building

From the Diagrams Above, you can see that the details of the Bar Bending Schedule for slab of a Building is being Stated. This Schedule help in purchase of the Reinforcements and also help the Iron Bender while Working.

BENEFITS OF BAR BENDING SCHEDULE

[1] With the use of bar bending schedule, mechanization of cutting and bending of reinforcement can be done, again reducing the cost and time of project and dependency on skilled labor requirement. It also improves the reliability on accuracy of bar cutting and bending.
[2] It enables easy and fast preparation of bills of construction works for clients and contractors.
[3] It becomes easy for site engineers to verify and approve the bar bending and cutting length during inspection before placement of concrete with the use of bar bending schedule and helps in better quality control.
[4] Bar bending schedule is very much useful during auditing of reinforcement and provides checks on theft and pilferage.
[5] When Bar bending schedule is available, cutting and bending of reinforcement can be done at factory and transported to site. This increases faster execution at site and reduces construction time and cost due to less requirement of workers for bar bending. Bar bending also avoids the wastage of steel reinforcement (5 to 10%) and thus saves project cost.

BAR CODE INDICATION OF REINFORCEMENT IN DRAWINGS

Engineering drawings is a language that communicate with details. Therefore there are standard code to indicate reinforcement in drawing such as:
5Y10-001-150 This means 5 Number of steel of 10mm Diameter, Bar mark 001, At 150mm Spacing.

Bar location can be vary as follows:

Notation for Slab:

T1 -Top outer layer

T2 -Top second layer

B1 -Bottom outer layer

B2 -Bottom second layer

CUTTING AND BENDING OF BARS

There is a steel yard in the site for storing, cutting and bending of bars. Reinforcement bars are cut into required lengths and bent into required shapes shown on the bar schedule either manually or by means of machinery.

In manual operations, laborers used the bar bending bench on which strong nails are fixed and GI pipes with suitable lengths to bend the bars. That is used for smaller diameter bars. For bending of larger diameter bars, bar bending machine is used. After bending all reinforcement bars were bundled and clearly numbered according to the bar mark so that steel fixers will not face any difficulty when fixing them.

HOW TO MINIMIZE BAR WASTAGE

On site, several steps were adopted for that purpose. Those are, Use of 12m long bars rather than using shorter bars. For example 6m bars off cuts of 12m bars were used to prepare stools, separators etc.

• Off cuts of larger diameter (25mm) bars-for spacer bars
• Off cuts of smaller diameter (10mm) bars-for stools

MATERIALS NEEDED IN SETTING OF REINFORCEMENTS

[1] SPACER BAR

Spacer Bar is use when there are 2 or more Layers of reinforcements, its most time use in Beams to space the reinforcements of different layer as shown in the image above.

[2] BINDING WIRE

Bars are jointed with using wires which is called “binding wires”. Hackers are used to bind these

[3] CONCRETE COVER

They were made up of 1:3 ratio of cement mortar. Concrete Cover should be immersed in water for 28 days to get the maximum strength. All the beams were checked to ensure adequate cover blocks are provided to the bottom and sides of the beam reinforcement. Main bars of the columns were adjusted to ensure the covering requirements before concreting. Stools of correct height were used to maintain the require gap between top and bottom reinforcement nets and cover blocks were also provided to bottom reinforcement.

[4] STIRRUPS OR LINKS

stirrups are usually one piece of steel that is bent into a rectangular/square/Triangle shape. The stirrup typically wraps around the bottom and top bars of the beams and Columns. A designer should specify the size, spacing and location along the length of the beam or column where the stirrups are required.  In my site specify the stirrup dimensions in our section drawings, so that the stirrup can be manufactured prior to installation. The installer should be careful to fabricate the stirrup from one piece of steel and adequately overlap each end.

[5] STOOLS

This is locally called Horse Leg, Stools are used to separate the top reinforcement mesh and bottom reinforcement mesh. Dimension of the Stools could be change as requirement. Those should be strength enough to bear the loads without changing the gap of two layers. 12 mm or 16 mm bars are used to make the stools.

 

 

Love this post and you love to get a copy

Click on either the button below to Get the PDF file and Read Offline.