BBS or Bar Bending Schedule is an important aspect of reinforcement detailing in construction projects. It is a process of summarizing all the reinforcement bars and steel quantities required for a reinforced concrete structure. The BBS provides crucial information for the procurement, cutting, bending, and placing of reinforcement bars. In this article, we will discuss everything you need to know about BBS of beam reinforcement and the calculation of steel quantities. From its definition to its significance in the construction industry, we will explore the intricacies of BBS and its role in ensuring a strong and durable structure. So, let us dive into the world of BBS and steel quantity calculation.
bbs of beam reinforcement and steel quantity calculation
BBS (Bar Bending Schedule) of beam reinforcement is a detailed chart that contains the information about the reinforcement bars required for a particular beam. This chart plays a significant role in determining the steel quantity for the beam reinforcement.
The process of preparing a BBS for beam reinforcement starts with understanding the design drawings of the beam. The design drawings provide all the necessary information about the beam such as dimensions, spacing, grades of bars, and the type of reinforcement needed.
The following steps are involved in preparing the BBS of beam reinforcement:
1. Gathering information: The first step is to gather all the necessary information from the design drawings and specifications. This includes the grade of concrete, size of beam, spacing of bars, and the type of bars to be used.
2. Determining the number of bars: Based on the size and spacing of the bars as specified in the design drawings, the number of bars needed for the beam reinforcement is determined.
3. Calculating the length of bars: Using the length of the beam from the design drawings, the total length of the bars required for reinforcement is calculated. This is important as it helps in estimating the total quantity of steel needed for the beam.
4. Creating a BBS chart: The BBS chart is created using the information gathered. It includes the details of each bar such as diameter, length, number of bars, and the shape of the bend.
5. Reinforcement detailing: The detailing of reinforcement bars is done to ensure that the bars are bent and placed correctly as per the design drawings. This includes the hook length, minimum spacing between bars, and lap length at the junctions.
The second aspect of beam reinforcement that needs to be addressed is the calculation of steel quantity. Steel quantity calculation for beam reinforcement is based on the following factors:
1. Concrete cover: The thickness of the concrete cover plays an important role in determining the steel quantity. A higher concrete cover requires more reinforcement to provide adequate strength and durability.
2. Bar spacing: The spacing between bars also affects the quantity of steel needed for beam reinforcement. The closer the bars are placed, the higher the steel quantity will be.
3. Beam size: The size of the beam also plays a significant role in calculating the steel quantity. A larger beam will require a higher quantity of steel for reinforcement compared to a smaller beam.
4. Design load: The design load on the beam is also considered while calculating the steel quantity. A higher design load will require more reinforcement to provide sufficient strength to the beam.
Using the BBS chart and the above factors, the steel quantity for beam reinforcement can be calculated. This calculation is essential for determining the cost of the reinforcement and also for ensuring the structural integrity and stability of the beam.
In conclusion, the BBS of beam reinforcement and steel quantity calculation are crucial aspects in the construction of beams. They ensure that the beams are strong and can withstand the design load while being cost-effective. It is essential to adhere to the design drawings and specifications, and follow the correct procedure for preparing the BBS and calculating the steel quantity for optimum results.
Types of reinforcement ( rebar) used in beam
Reinforcement, commonly known as rebar, is a crucial element in the design and construction of concrete structures. It is used to provide structural strength and prevent cracking or failure of the concrete members. In beams, rebar is placed in the tension zone to resist the tensile forces caused by the applied loads. There are various types of reinforcement used in beams, each with its unique characteristics and purposes. In this article, we will discuss the different types of reinforcement used in beams.
1. Plain Round Bars:
Plain round bars, also known as mild steel bars, are the most commonly used type of rebar in beams. They have a circular cross-section and have a smooth surface. These bars are made of low carbon steel and are mainly used in small and medium-sized beams. They are cost-effective and easy to handle, but their strength is limited compared to other types of reinforcement.
2. Deformed Bars:
Deformed bars, also known as heat-treated bars, are widely used in beam reinforcement. These bars have a ribbed surface that provides better bonding with the concrete, resulting in improved load-carrying capacity. Deformed bars come in various sizes and shapes, such as the twisted, ribbed, or indented design, depending on the specific needs of the structure. They are stronger and more durable compared to plain round bars, making them suitable for heavy-duty beams.
3. TMT Bars:
Thermo-Mechanically Treated (TMT) bars are one of the most advanced types of reinforcement used in beams. These bars are manufactured by subjecting hot-rolled steel bars to a series of cooling and heating processes. This treatment results in a high-strength, ductile, and corrosion-resistant metal. TMT bars are widely used in large and heavily loaded beams, such as those found in bridges and high-rise buildings.
4. Welded Wire Mesh:
Welded wire mesh, also known as wire fabric, is a prefabricated grid of interlocked steel wires. It is used as a form of reinforcement in beams, providing tensile strength and controlling cracking caused by the shrinkage of the concrete. Welded wire mesh is easy to handle, install, and transport, making it a popular reinforcement choice for beams in smaller construction projects.
5. Fibre Reinforced Polymer (FRP):
Fibre Reinforced Polymer (FRP) bars are a relatively new type of reinforcement used in beams. These bars are made of high-strength fibers, such as carbon, glass, or aramid, embedded in a polymer matrix. They offer excellent corrosion resistance, are lightweight, and have high tensile strength, making them suitable for use in marine and corrosive environments.
In conclusion, the type of reinforcement used in beams depends on various factors such as load, span, environment, and cost. It is essential to understand the different types of reinforcement available and their properties to select the most suitable one for a specific beam design. Properly designed and placed reinforcement can significantly improve the structural integrity and durability of a beam, ensuring the safety of the structure and its occupants.
BBS (Bar bending schedule) of beam
BBS (Bar Bending Schedule) is a detailed document used in the construction industry for the reinforcement of concrete structures. It is a list of reinforcement bars, their size, number, length, and shape required for the construction of a particular concrete element, such as beams, columns, slabs, etc. BBS is an essential component in the design and construction of reinforced concrete structures, and it is prepared by civil engineers or other professionals involved in the project.
In this article, we will discuss the BBS of beams, one of the most critical and frequently used elements in building construction.
Purpose of BBS for Beams:
BBS for beams provides the necessary information for preparing and placing reinforcement bars in the beam as per the structural design and drawings. It acts as a guideline for the construction team to ensure the proper placement and distribution of reinforcement bars to achieve the required strength and stability of the beam.
Components of BBS for Beams:
1. Beam details: The BBS starts with the details of the beam, such as its dimensions, span, load, and design strength. This information is necessary to determine the size and arrangement of reinforcement bars.
2. Reinforcement bar (rebar) details: The next section of the BBS lists all the reinforcement bars required for the beam. This includes the bar size, number, length, and shape. The length of the bars is calculated based on the beam’s dimensions, and the number is determined by the beam’s load-carrying capacity.
3. Bend and shape details: Bending and shaping of reinforcement bars are necessary to fit them into the beam’s formwork. The BBS provides the details of the bends and shapes needed for each bar to be placed correctly in the beam.
4. Bar marks: Each reinforcement bar in the BBS is assigned a unique identification number, known as bar mark. It helps in identifying and tracking the bars during the construction process.
5. Cutting length: The BBS also includes the cutting length of each bar, which is the length of the bar that extends beyond the beam’s edges. This length allows for the proper lapping and anchoring of the bars with adjacent or intersecting beams.
6. Bar spacing: The spacing between reinforcement bars is essential for maintaining the structural integrity of the beam. The BBS specifies the required spacing between bars to ensure proper concrete cover and adequate support.
7. Delivery schedule: The BBS also contains a delivery schedule, which outlines the expected delivery dates of the reinforcement bars. This helps in coordinating with the suppliers and ensures timely delivery of materials to the construction site.
Benefits of BBS for Beams:
1. Accurate reinforcement placement: The BBS ensures the proper placement of reinforcement bars in the beam, preventing any errors or miscalculations in the construction process.
2. Cost-effective: By providing the required information on bar sizes and numbers, the BBS helps in optimizing the use of reinforcement bars, reducing material waste and cost.
3. Time-saving: With all the necessary details readily available in the BBS, the construction team can efficiently carry out the reinforcement work, saving time and streamlining the construction process.
4. Quality control: BBS acts as a quality control measure by ensuring that the reinforcement work is carried out as per the design and specifications, resulting in a structurally sound and stable beam.
In conclusion, BBS for beams plays a vital role in the construction of reinforced concrete structures. It helps in optimizing
How to calculate cutting length of main bar in bbs of beam
To calculate the cutting length of main bar in the bar bending schedule (BBS) of a beam, you need to follow the following steps:
Step 1: Understand the Basics
To calculate the cutting length of the main bar, you need to have a basic understanding of the terms used in BBS. Main bar refers to the longitudinal reinforcement bars (usually steel) that provide strength to the beam. Cutting length is the length of a reinforcement bar that is required to be cut from a standard length to get the required size.
Step 2: Know the Formula
The formula to calculate the cutting length of the main bar is as follows:
Cutting Length = Development Length + Lapping Length
Where, Development Length = Ld
Lapping Length = Ll
Ld and Ll can be calculated using the following formulas:
Ld = 0.87 x fy x d / τbd
Where, fy is the characteristic strength of steel, d is the diameter of the bar and τbd is the bond stress.
Ll = l x d
Where, l is the number of bars to be lapped and d is the diameter of the bar.
Step 3: Determine Development Length
The development length of a reinforcement bar is the length required for the reinforcement to develop its full strength and bond with the concrete. It varies depending on the bond strength of steel and concrete, the diameter of the bar and the grade of steel used. It can be obtained from the relevant code or can be calculated using the formula mentioned in step 2.
Step 4: Determine Lapping Length
When the length of a reinforcement bar is not enough to span the entire length of the beam, it is necessary to join two or more bars by overlapping them. The lapping length varies depending on the diameter of the bar and the bond strength. It can be obtained from the relevant code or can be calculated using the formula mentioned in step 2.
Step 5: Calculate Cutting Length
Once the development length and lapping length are determined, the cutting length can be calculated using the formula mentioned in step 2. This will give you the total length from which the main bar needs to be cut.
Step 6: Consider Hooks and Bends
In some cases, the reinforcement bars may require hooks and bends for better anchorage and stress distribution. The length of these hooks and bends needs to be added to the cutting length to obtain the final cutting length of the main bar.
Step 7: Add Allowance for Wastage
It is advisable to add a certain percentage of wastage allowance (typically 2-5%) to the final cutting length obtained to accommodate any human error or wastage during construction.
In conclusion, to calculate the cutting length of the main bar in BBS of a beam, we need to have a basic understanding of the terms used, follow the relevant formula and consider necessary additions such as hooks and bends and allowance for wastage. It is important to accurately calculate the cutting length to ensure efficient use of materials and structural integrity of the beam.
cutting length of bent up bar in bbs of beam
Cutting length of bent up bar in bar bending schedule (BBS) of a beam is a crucial factor in the construction of any structure. It refers to the length of the reinforcing steel bar that is used to form a stirrup or a bent up bar at the end of a beam. This bent up bar is essential in providing strength and stability to a beam, especially at the compression zone.
The first step in determining the cutting length of the bent up bar is to have a clear understanding of the beam’s design and plan. The bending moment, shear force, and support conditions of the beam must be carefully studied to ensure that the reinforcing bar is correctly sized and positioned.
The general formula for calculating the cutting length of the bent up bar in BBS is given by:
Cutting Length = (A + B) + (C + D) + 2G
Where,
A = Straight length of the bar on one side
B = Lap length of the bar on the other side
C = Clear cover on one side
D = Clear cover on the other side
G = 90-degree bend allowance
The clear cover refers to the distance between the outer face of the concrete to the nearest edge of the reinforcing bar. It is important to provide the appropriate clear cover to protect the steel bars from corrosion and ensure proper bonding of the concrete.
The lap length of the bar is the overlap of two bars to provide a continuous reinforcement. It is essential to ensure that the overlap length is adequate to transmit the stress from one bar to another without causing any slipping or failure.
The 90-degree bend allowance refers to the extra length of the bar required to compensate for bending at right angles. It is generally taken as 10d, where d is the diameter of the bar.
After calculating the cutting length, it is essential to mark the steel bar accurately and cut it precisely to the required length. Any error in measurement or cutting can result in additional wastage of materials and time.
In conclusion, the cutting length of the bent up bar in BBS plays a significant role in the structural stability and strength of a beam. It is crucial to follow the design requirements and accurately calculate and cut the reinforcing bar to ensure the structural integrity of the beam.
weight of main bar and quantity calculation of main bar for bbs of beam
The weight of main bar and the quantity calculation of main bar are important aspects in the reinforcement of beams in civil engineering. Main bars, also known as longitudinal bars, are the primary steel bars used to resist tensile stresses in a beam. The weight and quantity of main bars in a beam play a crucial role in determining the strength, stability, and durability of the structure.
Weight of Main Bar:
The weight of the main bar is dependent on its diameter, length, and the specific density of the steel used. The standard unit for measuring the weight of steel bars is kilograms per meter (kg/m). The weight per meter of main bars can be calculated using the following formula:
Weight (in kg/m) = (D^2/162) x L
Where,
D = Diameter of the bar (in mm)
L = Length of the bar (in meters)
For example, let’s consider a main bar with a diameter of 12 mm and a length of 6 meters. Using the formula, the weight of the main bar would be calculated as:
Weight (in kg/m) = (12^2/162) x 6 = 5.33 kg/m
Quantity Calculation of Main Bar:
The quantity calculation of main bars is crucial in the preparation of the bar bending schedule (BBS). A BBS is a detailed document that provides the information about the quantity and location of all the reinforcement steel bars required for a particular structure. The following steps can be followed to calculate the quantity of main bars needed for a beam:
Step 1: Determine the section of the beam
The section of the beam refers to its dimensions and shape. For example, a rectangular beam would have a different quantity of main bars as compared to a T-shaped beam. The section of the beam is measured in millimeters.
Step 2: Calculate the center line length of the beam
The center line length of the beam is the length of the longitudinal axis of the beam. It can be calculated by adding the length of the top and bottom sections of the beam.
Step 3: Determine the spacing between the main bars
The spacing between the main bars is the distance between the main bars in the beam. It is measured in millimeters and can be calculated by dividing the width of the beam by the number of main bars required.
Step 4: Calculate the quantity of main bars
The quantity of main bars can be calculated by dividing the center line length of the beam by the spacing between the main bars. This will give the total number of main bars required for the beam.
For example, let’s consider a rectangular beam with dimensions 300 mm x 500 mm and a spacing of 150 mm between the main bars. The center line length of the beam would be calculated as (300+500+300)= 1100 mm. Using the formula, the quantity of main bars required for the beam would be:
Number of main bars = 1100/150 = 7.33 (rounded to the nearest whole number)
Therefore, the beam would require 7 main bars of 12 mm diameter, with a total weight of 5.33 kg/m each.
In conclusion, the weight and quantity of main bars are essential factors in the reinforcement of beams and must be accurately calculated to ensure the structural integrity and safety of a building.
quantity calculation of anchor reinforcement for bbs of beam
Quantity calculation of anchor reinforcement for BBS (Bar Bending Schedule) of beam is a crucial step in the design and construction process. Anchorage reinforcement provides stability and strength to the beam by transferring the load to the supporting structure.
The quantity of anchor reinforcement required for BBS of beam depends on several factors such as the type of beam, dimensions of the beam, design load, and seismic considerations. The following are the steps involved in the calculation of anchor reinforcement for BBS of a beam:
1. Determine the type of beam: The first step is to determine the type of beam based on the structural design. Beams can be of various types such as simply supported, cantilever, continuous, or fixed. This information is essential as it will help in determining the required anchorage length and spacing.
2. Calculate the design load: The next step is to calculate the design load that the beam will be subjected to. This load is usually determined by the structural engineer and includes factors such as dead load, live load, and wind load. The magnitude of the load will have a significant impact on the quantity of anchor reinforcement required.
3. Determine the depth of embedment: The depth of embedment is the length of the anchor that will be embedded in the supporting structure. It is usually calculated based on the type of beam, design load, and soil conditions. The greater the design load, the higher the depth of embedment required.
4. Calculate the length of the bar: The anchor reinforcement bars are usually extended beyond the edge of the beam to provide additional anchorage. The length of these bars is typically calculated as three times the effective depth of the beam.
5. Calculate the number of bars: The number of bars required for anchorage will depend on the size of the beam and the design load. The general rule is to provide a minimum of four bars, two on each side of the beam.
6. Determine the spacing of the bars: The spacing of the bars will vary depending on the type of beam and the design load. Generally, the bars should be evenly spaced, and the spacing should not exceed three times the diameter of the bar.
7. Calculate the total quantity: Once the length and spacing of the bars are determined, the total quantity of anchor reinforcement can be calculated by multiplying the total length with the number of bars.
In addition to the above steps, the design must also consider seismic forces, which may require additional reinforcement. The size and spacing of the bars may also vary depending on the local building codes and regulations.
In conclusion, the quantity calculation of anchor reinforcement for BBS of a beam is a critical aspect of the design process in order to ensure the structural stability and safety of the structure. It is essential to follow the proper procedures and calculations to determine the correct quantity of reinforcement needed for the specific beam.
total quantity of steel needed for bbs of beam
The total quantity of steel needed for bar bending schedule (BBS) of a beam depends on several factors such as the span of the beam, the load it will support, and the design specifications. In general, the steel reinforcement is used to increase the strength and stability of the beam.
To calculate the total quantity of steel needed for BBS of a beam, the first step is to determine the cross-sectional area of the beam. This can be done by multiplying the width, depth, and length of the beam. Once the cross-sectional area is known, the amount of steel required can be calculated using the following formula:
Steel Quantity (in kg) = Cross-sectional area of the beam (in m²) x Spacing of the bars (in mm) x Unit weight of steel (in kg/m³)
The spacing of bars is determined by the structural engineer based on the design specifications and is usually mentioned in the BBS. The unit weight of steel is a standard value which can be obtained from the standard codes or specifications.
For example, if the width of the beam is 0.3 m, depth is 0.3 m, and length is 5 m, the cross-sectional area would be 0.09 m². If the spacing of bars is 100 mm and the unit weight of steel is 7850 kg/m³, then the total quantity of steel required would be:
Steel Quantity = 0.09 m² x 100 mm x 7850 kg/m³ = 709.5 kg
This means that 709.5 kg of steel would be needed for the given beam. This quantity can be further broken down into the number and size of individual bars required to meet the spacing requirement. The BBS would include the details of the size, length, and number of bars needed for the beam.
In addition to the main reinforcement, beams also require stirrups or links to provide lateral support. The quantity of stirrups needed can also be calculated using a similar approach.
It is important to note that the total quantity of steel needed for BBS of a beam may also include an allowance for wastage, which can vary depending on the construction site and workmanship. Therefore, it is recommended to consult with a structural engineer for an accurate calculation of the steel quantity needed for a specific beam.
we have to calculate cutting length of stirrup
Stirrups are an essential component in reinforced concrete structures to provide lateral support and prevent shear failure. In simple terms, stirrups are the horizontal reinforcements that are used to hold the vertical bars, also known as main bars or longitudinal bars, together in a beam or column.
To ensure the structural integrity of the reinforced concrete element, the stirrups must be accurately placed and adequately spaced. This requires the calculation of the cutting length of stirrups. Cutting length is the length of the stirrup bar that is required to bend and insert into the concrete element.
The following are the necessary steps to calculate the cutting length of stirrups:
1. Determining the size of the stirrup:
The size of the stirrup is dependent on the size of the longitudinal bars and the structural requirements. The standard size of the stirrup bar is usually taken as one-eighth of the depth of the beam or column. For example, for a beam or column with a depth of 300mm, the size of the stirrup would be 37.5mm.
2. Finding the total length of the stirrup:
The total length of the stirrup is the sum of the required length for bending and overlap. The bending length is the distance between the two points where the stirrup bends to form the shape of the stirrup. The overlap length is the length of the portion of the stirrup that is inserted into the concrete for anchorage.
3. Determining the anchorage length:
The anchorage length is the length of the stirrup that is inserted into the concrete for proper anchorage. It is typically taken as 6 to 8 times the diameter of the longitudinal bar. For example, if the diameter of the longitudinal bar is 12mm, the anchorage length would be 72-96mm.
4. Calculating the bending length:
The bending length can be calculated using the following formula:
Bending length = (perimeter of the beam or column – 2 x cover) – (2 x 90° hooks)
Where, perimeter of the beam or column is the sum of all four sides, and cover is the distance between the outer surface of concrete to the nearest surface of the longitudinal bar.
5. Calculating the total length of the stirrup:
The total length of the stirrup can be calculated by adding the bending length and the anchorage length.
6. Subtracting the overlap length:
The overlap length is then subtracted from the total length of the stirrup to determine the cutting length.
Once the cutting length is calculated, it is essential to add an extra margin of 10-20% to account for any inaccuracies in bending and cutting the stirrup bars. This extra margin will ensure that the stirrups fit correctly inside the beam or column and provide adequate reinforcement.
In conclusion, the precise calculation of the cutting length of stirrups is crucial to ensure the structural stability of reinforced concrete elements. It requires expert knowledge and precision to accurately determine the required length of the stirrup bars for bending and inserting into the concrete. Any miscalculation can result in improper placement of the stirrups, which can compromise the structural integrity of the overall structure.
Conclusion
In conclusion, understanding the basics of bbs of beam reinforcement and steel quantity calculation is crucial for construction professionals. By properly calculating and placing reinforcement in beam structures, it ensures the safety and durability of the building. Being knowledgeable about the different types of bbs, their usage, and the calculation process can help in improving the quality and efficiency of construction projects. Continuous learning and staying updated with the latest techniques and standards in reinforcement and steel quantity calculation is essential for the success of any construction project. With proper planning and execution in this aspect, we can create stronger and more resilient buildings for the future.