The Civil Engineering Industry has a significant role in developing the nation to cater to the need for globalizing market scenarios. In every aspect of infrastructural development, the role and involvement of Civil Engineering experts are inevitable. The knowledge about the process and standards should be known to all. It will be much helpful for anyone, involving in Civil Engineering work at any time reference for their professional knowledge.
Design of Base and Foundation for the Earthquake-Resistant
Building
Abstract. The article presents the design of the base and foundation for the earthquake-resistant 5-
9-storey building of a rigid structural system. The main technical idea is to exclude the most
destructive components of seismic effects, which are transmitted to the lateral, and vertical walls of
basements and foundations, and to reduce the interaction forces of the foundation soils on the
foundation. The design of an earthquake-resistant base and foundation includes a solid reinforced
concrete foundation slab with criss-cross strips, freely supported on an intermediate sandy
cushion, which separates the soils from the foundation slab, and the channels around the
foundation.
Different types of Steel rebars are available from different companies. Selecting the best Steel rebar for construction is important for the strength and durability of the structure. In this article, we are going to look at how to check the quality of steel rebars based on type, brand, mass, dimension, quality, length and chemical composition and how to select the best steel rebar to build RCC Houses.
How to check the quality and select the best steel rebar for the construction of houses in India
1. Check the Type of Steel rebar
Steel rebars are popularly classified as follows based on their manufacturing process
1.1 TMT Bars
TMT bars are thermo-mechanical treated bars. . They are manufactured through a rapid cooling process to create a tough outer surface with a relatively ductile inner core. Hence TMT bars have a better balance between strength and ductility. In the present scenario, TMT bars are widely used for their following advantages.
Superior strength.
Good ductility and elongation.
Better Ribs projection for bonding.
Good weldability.
The TMT Fe500 and TMT Fe500D are two great choices for building all types of homes. Fe500D offers extra ductility. Fe500S is well suited for earthquake-prone areas.
1.2 CRS TMT Bars
CRS TMT bars are corrosion-resistant TMT bars. CRS TMT bars are treated to resist corrosion by epoxy coating or similar methods. They are ideal for building houses in erosive areas such as coastal areas.
1.3 HYSD Bars
HYSD bars are High Yield Strength Deformed bars. They are now replaced by TMT bars.
1.4 CTD bars
CTD bars are Cold-twisted Deformed bars. They were twisted at room temperature to increase strength. CTD bars have low strength, and low ductility and they are more prone to corrosion than other bars.
2. Visual Inspection for Rust and Identification Mark
Steel rebars should be free from rust and dust. Each running meter must have its brand name, diameter and grade details such as FE 500, and FE 550 D. Many branded steel bars come with a company tag.
3. Check for Uniform Mass/Weight
Steel rebars must have a homogeneous mass per unit length. Therefore, when choosing a steel brand for your construction, make sure that all steel rebars of the same diameter and the same length have the same weight.
4. Check for Minimum Mass/Weight
Check if the steel rebar has the following Minimum mass per meter according to the IS Steel Codebook.
Nominal size of Steel rebar
Minimum Mass per meter
4 mm
0.099 kg/m
5 mm
0.154 kg/m
6 mm
0.222 kg/m
8 mm
0.395 kg/m
10 mm
0.617 kg/m
12 mm
0.888 kg/m
16 mm
1.58 kg/m
20 mm
2.47 kg/m
25 mm
3.85 kg/m
28 mm
4.83 kg/m
32 mm
6.31 kg/m
36 mm
7.99 kg/m
40 mm
9.86 kg/m
The mass of the steel bar can be calculated from the popular formula d2/162. Examples are given in my other post.
The unit weight of steel is 7850 kg/m3.
Mass per cross-sectional area per meter is 0.007850 kg/mm2 per meter.
Sometimes there may be a slight deviation in the mass of the steel rebar, but according to the Indian Standard Steel Code book, the deviations should not exceed the tolerance percentage given below.
Nominal size of Steel Rebar
Mass Tolerance
0-10mm
+-7 %
12-16mm
+-5%
Above 16mm,
+-3 %
The Test specimens taken to check the mass of the steel bar should not be less than 500 mm
5. Check for Steel Grade/Strength
Steel rebars are classified into different grades based on their strength. For example, in the Fe415D standard, “Fe” stands for iron (steel), “415” denotes the Minimum Yield strength (tensile strength) of the steel bar and the letter D shows the ductile property of the steel bar.
The Yield strength and Ultimate Tensile strength required for steel rebars of different grades are given below. You can check the strength and elongation properties of the rebar in the labs with a help of any tensile testing machines like UTM.
Grade of Steel
Minimum Yield Strength
Minimum Ultimate Tensile Strength
Minimum Elongation Percentage
Fe415
415
485
14.5%
Fe415D
415
500
18%
Fe500
500
545
12%
Fe500D
500
565
16%
Fe550
550
585
10%
Fe550D
550
600
14.5%
Fe600
600
660
10%
In the latest amendment of the steel codebook, new grades like Fe415S and Fe500S have been added. These grades have higher ductility than other grades and are more suitable for earthquake-prone areas.
Grade of Steel
Minimum Yield stress
Maximum Yield stress
Minimum Elongation
Fe415S
415
540
20%
Fe500S
500
545
18%
6. Check for Length
Typically, steel rebars are provided in the form of 12-meter lengths and sometimes in the form of spirals during large construction operations. The length of the steel rebar shall not be less than 25 mm or more than 75 mm as specified in the bar specification.
7. Check for Ribs Projection
The Rib Projects on the HYST and TMT bars should not be less than the value given below. The Ribs help to create a good bond between the steel and the concrete.
Nominal size of Deformed Steel rebar
Minimum Ribs Projection
Less than 10mm
0.12mm
12mm to 16mm
0.15mm
above 16mm
0.17mm
8. Chemical Composition as per Indian steel codebook
Grade of Steel
Carbon
Sulphur
Phosphorous
Fe415
0.3
0.06
0.06
Fe415D/Fe415S
0.25
0.045
0.045
Fe500
0.3
0.055
0.055
Fe500D/Fe500S
0.25
0.40
0.40
Fe550
0.3
0.055
0.055
Fe550D
0.25
0.40
0.40
Fe600
0.30
0.40
0.40
9. Selection of Best Steel Rebar Brand for Construction of House
Cost is an important factor when it comes to choosing steel brands. Some cheap steel may not have the required quality, while some high-quality steel may be too expensive for our needs. Listed below are some of the well-known and well-known good quality steel brands.
TATA Steels – TATA Tiscom, TATA Tiscom SD
Tata is the most trusted brand in India. TATA Tiscom is a high-strength TMT ribbed bar. They provide good strength, ductility and elongation. TATA Tiscom SD is super ductile steel rebar. They have a high ductile ratio of 1.5, which prevents them from breaking under sudden loads. They are best suited for buildings in seismic areas to withstand seismic loads.
JSW Steels – JSW Neo steel
JSW is another popular and trusted brand. The JSW Neosteel 550D is a high-strength TMT ripped ductile bar with good uniform mass, strength and ductility. Other popular steel brands are Visakh Steel, Essar Steel, Camden Steel and Amman Steel.
Like in any other industry, keeping up with trends in the civil engineering field is a requirement for any company that wants to remain competitive in a market full of innovation, advances, and transformations. With the creation of better machinery, new technologies, sustainable materials, and fresh perspective the field is progressing every second. Here are the top civil engineering trends for 2022.
Industrialized Construction
Modular assembly of prefabricated parts is a technique that has been taking up more and more space over the last few years, mainly in large-scale works. Previously, only major works benefited from prefabricated technologies, today it is accessible for small enterprises to make more and more constructive models benefit from it. 3D printers allow the building of customized pre-moulded pieces quickly and without wasting materials. Thanks to these technologies guarantee more speed, a better standard of quality and durability, and a better cost-benefit ratio.
Use Of Drones
Drones are increasingly common items in the construction segment. They are very practical to the field given their ability to capture photos, and videos, and even to make measurements in places difficult to access, allowing for initial data to be collected. At the same time, they are helpful for commercial matters as footage collected works for advertising. Due to its popularization prices are expected to fall, making its cost-benefit even better.
Smart Urbanization
Buildings and the entire urban space in which they are integrated will undergo marked changes over the years. Thanks to new technologies the capacity of urban planning will be better and more systemic, hence improving people’s quality of life. Social impact plays an important role in construction now more than ever, and it is key for engineers to meet both individual and collective needs.
Automated Machines
The use of human labour can be a risk to the employee’s health, depending on the person it can also mean low productivity, low quality of service, or even dangerous work. With this in mind, professionals in the field are creating methods to carry out construction stages in an automated way through machines that do all the physical work. For example, through Artificial Intelligence (AI), machines can build walls with a shallow margin of error. Robotic equipment is key in reducing the risk of accidents with workers.
The construction sector has shown significant progress in accepting technological changes in construction processes. With new technologies and materials, it is possible for the civil engineering field to be one that brings out the best of cities as well as offers new living possibilities for all of us.
The volume of concrete required = 0.038 m3/square feet area
Example:-If Plan Area = 40 x 20 = 800 Sq. m.
So, for the plan area of 800 Sq. m. the area the total volume ofconcrete required
= 800 x 0.038m3 = 30.4m3
2. Thumb Rule for Steel Quantity for Slab, Beams, Footings & Columns
Following are some important thumb rules for steel calculation for slab, beam, column, and footings.
Steel required in residential buildings = 4.5 Kgs – 4.75 Kgs / sq. Ft.
Steel required For Commercial buildings = 5.0 Kgs-5.50 Kgs/Sq. Ft.
You can also use BN Dattarecommendations for the more accurate result,
The following recommendations Thumb Rules For Civil Engineering are given in B N Datta for the Steel quantity used in different members of the building.
1) Slab– 1% of the total volume of concrete (Slab steel calculation thumb rule) 2) Beam– 2% of the total volume of concrete 3)Column– 2.5% of total volume of concrete 4) Footings – 0.8% of the total volume of concrete
Example:
How to calculate the steel quantity of slab having the Length, width, and depth of the slab is 5m x 4m x 0.15m
Step 1: Calculate the Volume of Concrete:
The Total Volume of Concrete for given Slab = 5 x 4 x 0.15
= 3m3
Step 2: Calculate The Steel Quantity Using Formula:
As per the guidelines are given in the BN Dutta reference book the steel quantity of slab is 1% of the total volume of concrete utilized.
Thumb rule to estimate Steel quantity of above slab = Volume of Concrete x Density of Steel x % of Steel of Member
Steel weight required for above slab = 3 x 7850 x 0.01 = 235Kgs
Shutteringcosts are taken as 15-18% of the total construction of the building. Shuttering work is done to bring the concrete in Shape. The Thumbrule to estimate the shuttering required is 6 times the quantity of concrete or 2.4 times of thePlinth area.
For example, the concrete quantity is 0.5m3, then
Area of Shuttering is 0.5 x 6 = 3m2
Components of Shuttering
Shuttering Ply Quantity estimation
The Shuttering plate Ply, Battens, Nails are components of Shuttering.
Suppose, The Shuttering Ply has a length, width & depth of 2.44 x 1.22 x 0.012
The No. of ShutteringPly Sheets = 0.22 times of Shuttering
Suppose, the Shuttering Area = 3m
Then Ply required for shuttering = 0.22 x 3 = 0.66m2
5. Battens Quantity Calculation
Shuttering Batten usually has a length & width of 75mm x 40mm.
Batten Quantity = 19.82 x No. of Ply Sheets
If work requires 25 Ply sheets, the total quantity of Battens are 19.82 x 25 = 495 Battens
Nails & Binding Wire Quantity in Shuttering:
Approximately, 75 grams of Nails were used in the shuttering of the 1m2 area.
75gms of Binding wire is used for every 1m2 of Shuttering.
Thumb rule for Shuttering oil estimation :
Shuttering oil is applied on the shuttering platesurface used to de-frame or de-assemble from the concrete easily.
Total required Shuttering oil = 0.065 x Total Area of Shuttering
(or)
For every 15m2 of shuttering 1 liter of shuttering oil is consumed.
Example :
If, total area of shuttering is 15 m2, then Shuttering oil Consumption = 0.065 x 15 = 0.975.
