Any where in the length of the beam two bars should be placed for both top and bottom locations. So any bat other than the two is called extra bar. In your calculation provide two of the bars throughout the beam length and perform curtailment ( cutting the bar after its development length).

Hereof, how do you calculate extra bars on a beam?

Example of Beam Reinforcement Calculation:

1. Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length.
2. Length of bar B2: A + B + C = 4000 + 2 x 230 – 2 x 40 + (1.414xH – H)
3. B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 4518.3 = 4520mm.

Subsequently, question is, what is top and bottom reinforcement? As tension and compression happens in the opposite zone of the concrete, usually one on the upper and the other on the lower, steel can be categorized as top reinforcement and bottom reinforcement by the location where it is put into the concrete. Also, they are often called longitudinal reinforcement.

In this way, what is extra top bar in slab?

You may provide extra bars if it is framed structure, and if the slab is monolithic with the edge beam due to fixity. Otherwise there may be some cracks will develop before the moment is thrown to the span from support. If it is simply supported say on masonry wall or so, then no extra bars are required.

What is extra bar in beam?

An extra bar or a threaded rebar is provided in a beam to support the hogging moments at the end parts of the beam. Also, extra bars are used to hang the stirrups of the beam.

Related Question Answers

How do you determine the weight of a bar?

1. Weight of STEEL BAR.
2. Weight = Density x Volume {Volume = Area x Length }
3. Density of Steel = 7850 Kg/m3.
4. Area of Steel = pi x d^2 / 4.
5. = 0.785 d^2.
6. Taking, Bar Length =1000 mm = 1 m.
7. Therefore, we can calculate.
8. Weight of Steel Bar = {7850/(1000x1000x1000)} x (3.14 x d^2 /4)x1000.

How do you calculate the length of a bar on a beam?

Example of Beam Reinforcement Calculation:

1. Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length.
2. Length of bar B2: A + B + C = 4000 + 2 x 230 – 2 x 40 + (1.414xH – H)
3. B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 4518.3 = 4520mm.

What is bar bending schedule?

Bar Bending Schedule, commonly referred to as “BBS” is a comprehensive list that describes the location, mark, type, size, length and number, and bending details of each bar or fabric in a Reinforcement Drawing of a Structure.

How do you determine cutting length?

Steps involved in finding the cutting length of stirrups:-

1. Look at the size of column or beam from drawings.
2. Adopt Dia of the bar (generally 8mm Dia is used for stirrups)
3. Deduct the concrete cover or clear cover.
4. Find the total outer length of stirrup after deducting concrete cover.

How do you calculate the length of a beam?

Example of Beam Reinforcement Calculation:

1. Length of B1 = clear distance between walls + 2 x width of walls – 2 x bar cover + 2 x bend length.
2. Length of bar B2: A + B + C = 4000 + 2 x 230 – 2 x 40 + (1.414xH – H)
3. B2 = 4000 + 2 x 230 – 2 x 40 + (1.414×334 – 334) = 4518.3 = 4520mm.

How do I add an extra bar to a slab?

Extra Bars:- The extra bar is provided at the bottom of Cranked bars to maintain the framework of the slab. The length of Extra bar is L/4. Deduct the cover for finding length of bar. Compute the Total wt of steel required for slab reinforcement.

Why we use extra bar in slab?

The rebar keeps the concrete from flexing; thereby making it stronger. It is now common (upon request) to include little filaments of plastic into the cement as it is being mixed and it makes the concrete stronger also.

How do you calculate the number of reinforcing bars in a slab?

The quantity is done in two steps.

1. (Calculation of Bars No's) First, calculate the number of bars required (main and distribution both). FORMULA = (Total length – Clear cover)/center to center spacing + 1. Main bar = (5000 – (25+25))/100 + 1. = 4950 Divided by 100 + 1. = 51 Bars.
2. (Cutting length)

Why reinforcement is provided in top layer of slab?

Distribution bars placed on top of the main bar. Main Reinforcement Bars are used to transfer the bending moment developed at the bottom of the slab. Distribution Bars are used to hold the slabs on either way and to resist the cracks and shear stress developed at the top.

How do you measure a slab crank bar?

Slab thickness = 150mm. Development length, Ld = 40d. D = slab thickness – 2*clear cover – diameter of bar = 150 – 2*25 – 12 = 88mm.

What is 2way slab reinforcement?

Reinforcement detailing of a slab is done based on its support conditions. Slab may be supported on walls or beams or columns. Slab supported directly by columns are called flat slab. On the other hand, when slab is supported on all four sides and bending take place in two directions are said to be Two Way Slab.

How do you calculate steel for a slab?

UNIT WEIGHT X TOTAL LENGTH gives you the WEIGHT OF STEEL. You need to calculate how much concrete is required to cast the member first. Example: Consider slab area is 400 square meter, thickness of the slab is 150 mm. Concrete quantity required to cast this slab is 400*0.15 = 60 Cubic meter.

What is Main Bar and distribution bar in slab?

Main bar and distribution bars are defined for Slab. The bars provided along critical direction of bending is called main bars and the bar provided along other direction is called distribution bars. for a one way slab main bars are provided along shorter span and distribution bars are provided along longer span.

How do you calculate steel for a roof slab?

Calculate the length of 1 bar and multiply it with the number of that bars. When you get the total length of bars then multiply it with weight of bar. At last summation of total weight is the required quantity of steel.

What is the minimum spacing of stirrups?

Minimum spacing of stirrups should not be more than 250mm .

What is the maximum spacing of stirrups?

Minimum spacing between two bars can be taken as approximately 50–75 mm. According to cl. 26.5. 1.5 of IS 456, the maximum spacing of the stirrups = 0.75 d = 0.75 (450) = 337.5 mm = 300 mm (say).

How do you calculate the weight of steel?

1. You can easily calculate the mass of the given steel bar, by knowing its section and length.
2. Volume Vof the bar = area of cross-section if the bar × length of the bar,
3. Mass of the bar = Volume of the bar × density of steel.
4. Density of steel = 8.05 g/cm³.

How do you calculate beam and column size?

For Beam:

1. 230 mm x 450 mm excluding slab.
2. Volume of Concrete = 0.23 x 0.60 x 1 =0.138m³
3. Weight of Concrete = 0.138 x 2400 = 333 kg.
4. Weight of Steel (2%) in Concrete = = 0.138 x 0.02 x 8000 = 22 kg.
5. Total Weight of Column = 333 + 22 = 355 kg/m = 3.5 KN/m.

How do you calculate stirrups spacing in a column?

As per code provision the stirrups spacing should be least among the :

1. Least lateral dimension of the column.
2. 16 times the diameter of longitudinal main bar.
3. Not more than 300 mm c/c.

What is meant by 2 legged stirrups?

When we use a single stirrup to tide a beam or column at a time, we say it is two leg stirrup and thus if we use Double stirrup to tide a beam or column at a time, we say it is four leg stirrups. A single stirrup have two leg.

What is top reinforcement?

As tension and compression happens in the opposite zone of the concrete, usually one on the upper and the other on the lower, steel can be categorized as top reinforcement and bottom reinforcement by the location where it is put into the concrete. Also, they are often called longitudinal reinforcement.

What is 2way slab?

Two way slab is a slab supported by beams on all the four sides and the loads are carried by the supports along both directions, it is known as two way slab. In two way slab, the ratio of longer span (l) to shorter span (b) is less than 2. So, main reinforcement is provided in both direction for two way slabs.

What is RCC slab?

RCC slab: reinforced cement concrete slab. It has a combination of steel bars and concrete. Steel bars are placed in concrete with calculated spacing. Cover thickness if concrete is provided around the bars. Bars are tied properly to avoid displacement during pouring of concrete.

What is slab and its types?

Concrete Slab Types – Construction, Cost, and Applications. Concrete slabs, therefore, are further classified into one-way joist slab, flat slab, flat plate, waffle slab, hollow core slab, precast slab, slabs on grade, hardy slab, and composite slab.

Where is one way slab used?

Types of Designs for One-way Slab

• There are mainly three types of designs for one-way slab.
• In one-way solid slab (with beams) system, the slab is supported on beams.
• One-way Ribbed Slab (with beams)system is used for the office buildings (low rise), parking structures, and warehouses.

How do I calculate how much rebar I need?

Assume your longitude is 15 feet and there will be 14 inches between latitude rebar.

1. Convert your longitude measurement into inches: 15 x 12 = 180.
2. Divide your result by the spacing measurement: 180 / 14 = 12.87 (round up to 13)
3. Add one rebar to your result: 13 + 1 = 14.

What is oneway slab?

One way slab is a slab which is supported by beams on the two opposite sides to carry the load along one direction. In one way slab the ratio of longer span (l) to shorter span (b) is equal or greater than 2. i.e Longer span (l)/Shorter span (b) ≥ 2.

What is the use of stirrups in beams?

Stirrups are provided to hold the main reinforcement rebars [1] together in an RCC structure. Stirrups are placed at proper intervals to beams and columns to prevent them from buckling. Also, they protect RCC structures from collapsing during seismic activities (earthquakes).