HOW TO CALCULATE LOADS ON COLUMNS

The load calculation for a column depends on the type of load.

TYPES OF LOADS ON COLUMN:

Self weight of the column x Number of floors
Self weight of beams per running meter
Load of walls per running meter
Total Load of slab (Dead load + Live load + Self weight)
The columns are also subjected to bending moments which have to be considered in the final design. The best way to design a good structure is to use advanced structural design software like ETABS or STAAD Pro. These tools are leagues ahead of manual methodology for structural design, and highly recommended.
In professional practice, there are some basic assumptions we use for structural loading calculations.

FOR COLUMNS:

Self weight of Concrete is around 2400 kg per cubic meter, which is equivalent to 240 kN. Self weight of Steel is around 8000 kg per cubic meter. Even if we assume a large column size of 230 mm x 600 mm with 1% steel and 3 meters standard height, the self weight of column is around 1000 kg per floor, which is equivalent to 10 kN. So, in my calculations, I assume self weight of column to be between 10 to 15 kN per floor.

FOR BEAMS:

Similar calculations as above. I assume each meter of beam has dimensions of 230 mm x 450 mm excluding slab thickness. So, the self weight can be around 2.5 kN per running meter.

FOR WALLS:

Density of bricks varies between 1500 to 2000 kg per cubic meter. For a 6″ thick wall of 3 meter height and a length of 1 meter, we can calculate the load per running meter to be equal to 0.150 x 1 x 3 x 2000 = 900 kg which is equivalent to 9 kN/meter. You can calculate load per running meter for any brick type using this technique.
For autoclaved, aerated concrete blocks like Aerocon or Siporex, the weight per cubic meter is between 550 to 700 kg per cubic meter. By using these blocks for construction, the wall loads per running meter can be as low as 4 kN/meter, which can result in a significant reduction in the cost of construction.

FOR SLAB:

Assume the slab has a thickness of 125 mm. Now each square meter of slab would have a self weight of 0.125 x 1 x 2400 = 300 kg which is equivalent to 3 kN. Now, assume Finishing load to be 1 kN per meter and superimposed live load to be 2 kN per meter. So, we can calculate slab load to be around 6 to 7 kN per square meter.

FACTOR OF SAFETY:

In the end, after calculating the entire load on a column, please do not forget to add in the factor of safety. For IS 456:2000, the factor of safety is 1.5.
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Simple Derivation of W=D²L/162, the Formula to Calculate Weight of Steel bars


Diameter and length of steel bars are structural requirements of a building, and they are decided based on design procedures given by IS(Indian Standard) codes. Steel bars are sold in the market in price per weight. So we need to calculate the weight of steel required to estimate cost of construction.
The formula D²L/162 is very common and used frequently to calculate the weight of steel bars. In this post, the simple derivation behind this formula is discussed. I hope you will enjoy it.

The formula to calculate the weight of steel is:

W=D²L/162
Where,
W = Weight of steel in Kg
D = Diameter of steel bars in millimeters (mm)
L= Length of steel bars in meter (m)

Derivation of the Formula:

We know that,
Volume= Cross-sectional area x Length 
Weight = Volume × Unit weight
Mathematically,
W = A x L x ρ
A = Area = πD²/4
π (pi) = 3.14
D = Diameter of steel bar
L = Length of steel bar
ρ (Rho) = Density of steel bar = 7850 kg/m³
Therefore,
W = 3.14 x D²/4  x L x 7850 kg
Where D and L are in m

We generally express diameter in millimeter (mm) and length in meter (m) unit. So to make the formula more handy let's take diameter as D mm.
D mm = D/1000 m
Putting D mm value in the expansion of W,
W = 3.141 x (D/1000)²/4 x L x 7850 kg
Or, W = D²L/162 kg
D in mm
& L in m
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A model paper for SSC JE is shared in this post. Click on the download link given below and get the pdf. If you are appearing for SSC JE exam, then give it a try.
CLICK HERE TO DOWNLOAD

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A Precise Note On Open Channel Flow

Fluid Mechanics is a very important subject in Civil Engineering, both from application and exam point of view. It has a significant weightage in almost all competitive exams. Though this subject is common to other branches also, chapter wishes weightage varies from branch to branch. For our branch Open Channel Flow (OCF) is the most important one and enjoys most portion of weightage alone. 
So we thought a really short and precise note on this chapter may be helpful for our readers, and here in this post we are going to share it in pdf format. Must download and give it a try. If you found it useful then share with friends.
CLICK HERE TO DOWNLOAD

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HOW QUALITY OF CEMENT IS CHECKED AT SITE


Cement is probably the costliest ingredient in concrete. Strength of Concrete structures is largely affected by quality and type of cement used in construction. 
Both from economic and safety point of view it is very much advicable to check the quality of cement by thorough inspection. In this post we are going to discuss some simple yet useful methods that are very popular for this purpose and are commonly used in sites.
Lets discuss them one by one.

1. DATE OF PACKAGING:

Strength of cement reduces with time. So the date of packing given by manufacturer should be checked prior to buying. Cement should be used before 90 days from packaging date. For a better clarity the percentage of lose in strength of cement with respect to time is given in the following table.

2. COLOUR OF CEMENT:

Cement of good quality has gray colour with greenish shade. The colour should be uniform throughout.

3. CHECK FOR LUMPS:

No lumps should be present in the cement. Lumps are formed due to absorption of moisture from the climate.

4. RUBBING TEST:

Cement should feel smooth while rubbing in between fingers. If it gives a rough feeling that means cement is mixed with sand.

5 TEMPERATURE TEST:

Simply insert your hand into the cement bag, it should give cool feeling if its quality is good. Otherwise, you may feel warm because of hydration reaction.

6. FLOAT TEST:

Take some amount of cement and throw it in water. The cement should float for sometimes before it sinks in the water.

7. SETTING TEST:

Make a thick cement paste with water and immerse it in water for 24 hours. It should be set and should not develop cracks.

8. STRENGTH TEST:

Prepare a cement block of 25 mm x 25 mm and 200 mm in length. Now submerge it in water for 7 days. Now place it on supports 15 cm apart and load it with 34 kg weight. Block made from good cement will not show any signs of failure.
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Subject Wise WEIGHTAGE Analysis Of GATE

Depending on past year trends of the examination we have prepared subject wise weightage analysis for all subjects in the syllabus , you may find it useful while preparing for the exam. Let's have a look on it.

Engineering Mathematics:


Hydrology:


Surveying:


Environmental Engineering:


Geotechnical Engineering:


Fluid Mechanics:


Strength of Materials:


Highway Engineering:


RCC:

Structural Analysis:



Steel Structure:


Irrigation:


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Subject Wise Weightage Analysis For ESE

Indian Engineering Services abbreviated as IES are the civil services that meet the technical and managerial functions of the Government of India. Like most countries, the Government of India recruits its civil servants and officials on the basis of merit, the middle management positions in the bureaucracy are buried through competitive exams. Large number of candidates take these exams, competing for limited posts. IES officers are selected by the union government on the recommendations made by the Union Public Service Commission (UPSC). A combined three-stage competitive examination (comprising five tests), called the Engineering Services Examination (ESE) is conducted by the UPSC for recruitment to the Indian Engineering Services.

In Y-axis: Total marks asked in last 20 years.
In X-axis: Subjects













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HOW TO CALCULATE LOADS ON COLUMNS

The load calculation for a column depends on the type of load. TYPES OF LOADS ON COLUMN: Self weight of the column x Number of floors ...