This document provides guidelines for designing columns, including three important thumb rules: 1) The size of columns should be no less than 9"x9" for a single story structure and larger for taller structures; 2) The distance between columns should not exceed 4m for 9"x9" columns and larger columns are needed for greater distances; 3) Columns should be aligned in straight lines or a grid to avoid structural issues. It emphasizes the importance of following these rules to prevent disastrous mistakes by engineers that could compromise safety and cost lives.

1. Guidelines to be followed for Designing a column
Today, we will discuss something very general. Inspite of knowing these general thumb rules, Civil
Engineers still end up making disastrous mistakes which would not only cost them but also cost the
people living in the building designed by these engineers.
Earlier, I wrote an article describing one of my projects where structural designing was executed on
site (which was extremely pathetic) even before Architectural design was done. (Check
out: Consequences of Wrong Structural Design | Live Project example)
In this article, we will go through the essential thumb rules to be followed for giving a column
layout. Ofcourse RCC columns have to be designed in accordance to the total load on the columns
but apart from that it is essential for every Civil engineer and Architect to remember a few thumb
rules so that they are prevented from making mistakes.
Three thumb rules to be followed are as follows:
1. Size of the Columns
2. Distance between Columns
3. Alignment of columns
Thumb rule no.1
Size of the columns
The size of the columns depends on the total load on the columns.
Minimum size of the column should not be less than 9‖x9‖.
9‖x9‖ columns are to be used for a single storey structure with M15 grade of concrete.
In case, 9‖x9‖ column size is to be used for 1 and half storey structure, then it is advised to use M20
grade concrete.
A safe and structurally sound column size for a 1 and half storey structure should not be less than
12‖x9‖ using M15 grade concrete. This should be in your most preferred and practical options list.
Thumb rule no.2
Distance between the columns
Try to maintain equal distance between the centres of two columns. Always plan a column layout on a
grid.
The distance between two columns of size 9‖x9‖ should not be more than 4m centre to centre of
column.
If larger barrier free distances are required then going for larger column size is to be used.

2. The size of the columns increase because of two factors:
1. Increase in the distance between two columns (This increases the dimensions of the columns as
well the depth of the beam.)
2. Height of the building (Increase in the number of floors is directly proportional to the dimensions
of the columns.
Thumb rule no.3
Alignment of Columns
A rectangular grid is to be made for placing the columns. This helps in avoiding mistakes and placing in
columns can be done in the right way.
The columns can preferably be arranged in two different fashions:
1. In a straight line with the help of a grid
2. In a circular fashion for circular buildings.
Zigzag arrangement of columns is an absolutely wrong way of working out Structural design. It should
be remembered that when columns are erected, beams are laid connecting the columns.
The Zigzag column placement causes three major issues:
1. Unbalanced load transfer
2. Problems in wall construction
3. Problems in laying beams
If these three thumb rules are followed by Civil Engineering and Architecture students,
implementation of wrong Structural design can be prevented.
In the next article, I will explain these three thumb rules with the help of an example.
Consequences of Wrong Structural Design | RCC Structures
A lesson for all the Civil Engineers and Designers to learn
I got a project of designing (Architectural Design) a Hostel in Lucknow, India. The Structural design that
is, column positions and wall construction was already done. The client wanted me to design a Hostel
keeping the column positions and exterior wall construction intact. I have written this article to
address all the Civil engineering students as well as Civil Engineers to avoid making such blunders while
they design. Please do read this article because understanding the intensity of the job of a Civil
Engineer is must for every student and professional. I guess this realization has been washed away and
forgotten in the wave of commercialism.
Hostel Design, Lucknow, India
The client mailed me the layout of the existing construction. After I studied the layout, I figured out
that the Column layout was pathetic. I wonder what kind of Civil Engineer must have made the layout
or if at all any Civil Engineer has done it.

3. Errors in Construction
Wrong size of the Columns
The size of the columns was 9‖x9‖ and the building is supposed to be constructed upto G+2 floors
which is really disastrous for the structure.
It could lead to structural failure and ultimately structural collapse.
(The duty of the Civil Engineer is to understand and not make such dramatic blunders. The
consequences of this kind of structural design could be disastrous.)
Column layout and Exterior wall Construction
9‖x9‖ size columns are only preferred if you were to construct only a ground floor structure using M15
grade concrete. If you are to construct another floor that is (G+1), the minimum size of the column
should not be less than 9‖x12‖ using M15 grade concrete.

4. If the client insists on using smaller columns (9‖x9‖); in that case, use of M20 grade concrete should be
done mandatorily and the construction should not be initiated before the client agrees to do so.
Wrong alignment of the columns
None of the columns are aligned in a straight line. If we are to construct a wall connecting the
columns, it is not possible to get a straight wall. It is so incorrect. I wonder how the beams are going to
rest on the columns.
(It is my request to all the Engineering students and Civil Engineers to avoid making such terrible
mistakes or rather I should firmly say that do not make such blunders. It is an insult to the field
of Civil Engineering. Your mistakes will cost you as well as others. The collapse of one structure
designed by you can ruin your entire career. Your own life and others lives are also in your
hands. So please be careful.)
Wrong wall construction
The exterior wall construction has also been done incorrectly. The walls just don‘t merge at a
particular corner. Do remember that when you don‘t have a column construction in a corner, two
beams come together and rest on each other which supports your structure.
Design of Foundations
Foundations
Foundation of a structure is like the roots of a tree without which the tree cannot stand. The
construction of any structure, be it a residence or a skyscraper; starts with the laying of foundations.
Before designing the foundation, the type of soil is determined. Depending on whether the soil is hard
soil or soft soil, a specific type of foundation is adopted.

5. Shallow Foundations versus Deep Foundations
Foundations are made in various materials… They could be reinforced cement concrete foundations or
brick foundations or stone rubble masonry foundations etc. The choice of material to be used in the
construction of foundations also depends on the weight of the structure on the ground.
The bearing capacity of soil plays a major role in deciding the type of foundation. The safe bearing
capacity of soil should be 180N/mm2 to 200N/mm2.
Foundations are broadly classified into shallow foundations and deep foundations. The depth of the
foundation means the difference of level between the ground surface and the base of the foundation.
If the depth of the foundation is greater than its width the foundation is classified as a deep
foundation.
.
What would you do in case of a RCC staircase having cracks?
The development of cracks occurring in RCC staircase is one of the major problems to deal with in RCC
construction.
Before we go to the ultimate solution of the repair of cracks in a staircase, I would want all the
students to know that, ―Design in a way that you would never have to look for solutions‖.
This is an important matter. The graver the problem, the harsher and shorter the solution is….

6. Basic elements of Staircase
Earlier, in one of my article, I have explained the “Design of RCC Staircase”. Please do go through
before designing…
. RCC Structures
RCC Structures are nothing but reinforced concrete structures. RCC structure is composed of building
components such as Footings, Columns, Beams, Slabs, Staircase etc.
These components are reinforced with steel that give stability to the structure. Staircase is one such
important component in a RCC structure.
In this article, we will discuss different types of staircases and study the RCC design of a dog-legged
staircase

7. Dog Legged Stair
Stairs
Stairs consist of steps arranged in a series for purpose of giving access to different floors of a building.
Since a stair is often the only means of communication between the various floors of a building, the
location of the stair requires good and careful consideration.
In a residential house, the staircase may be provided near the main entrance.
In a public building, the stairs must be from the main entrance itself and located centrally, to provide
quick accessibility to the principal apartments.
All staircases should be adequately lighted and properly ventilated.
Various types of Staircases
 Straight stairs
 Dog-legged stairs
 Open newel stair
 Geometrical stair

8. RCC design of a Dog-legged staircase
In this type of staircase, the succeeding flights rise in opposite directions. The two flights in plan are
not separated by a well. A landing is provided corresponding to the level at which the direction of the
flight changes.
Design of Dog-legged Stairs
Based on the direction along which a stair slab span, the stairs maybe classified into the following two
types.
1. Stairs spanning horizontally
2. Stairs spanning vertically
Stairs spanning horizontally
These stairs are supported at each side by walls. Stringer beams or at one side by wall or at the other
side by a beam.
Loads
 Dead load of a step = ½ x T x R x 25
 Dead load of waist slab = b x t x 25
 Live load = LL (KN/m2
)
 Floor finish = assume 0.5 KN/m
Stairs spanning Longitudinally
In this, stairs spanning longitudinally, the beam is supported ay top and at the bottom of flights.
Loads
 Self weight of a step = 1 x R/2 x 25
 Self weight of waist slab = 1 x t x 25
 Self weight of plan = 1 x t x 25[(R2
+ T2
)/T]
 Live load = LL (KN/m2
)
 Floor finish = assume 0.5 KN/m
For the efficient design of an RCC stair, we have to first analyse the various loads that are going to be
imposed on the stair.
The load calculations will help us determine, how much strength is required to carry the load. The
strength bearing capacity of a staircase is determined on the amount of steel and concrete used.
The ratio of steel to concrete has to be as per standards. Steel in the staircase will take the tension
imposed on it and the concrete takes up the compression.
These are the essential steps that are to be followed for the RCC Stair Design.

9. RCC staircase cracks
There are two types of cracks, they are;
1. Minor cracks or surface cracks
2. Major cracks or structural Cracks
Like I said before, the graver the problem, the shorter and harsher the solution….
In case of minor cracks (surface cracks) occurring in the RCC staircase , the cracks can be filled up
with the help of plastering. Surface cracks are not very harmful to the structure. They only result in
marring the aesthetics of the built space.
In case of major cracks (structural cracks) that is causing vibrations when someone walks on the
staircase, the staircase has to be broken and then recast again. (Remedy is as short as it could be)
RCC Column
A column forms a very important component of a structure. Columns supportbeams which in turn
support walls and slabs. It should be realized that the failure of a column results in the collapse of the
structure. The design of a column should therefore receive importance.
Supporting the slabs is the main function of the columns… Such slabs are called Simply Supported Slabs.
Simply supported slabs could be either one way slab or a two-way slab. It depends on the dimensions of
the slab.
A column is defined as a compression member, the effective length of which exceeds three times
the least lateral dimension. Compression members whose lengths do not exceed three times the
least lateral dimension, may be made of plain concrete.
In this article, we are going to discuss in detail the basis of classification of columns and different types
of reinforcement required for a certain type of column.
Reinforced Cement Concrete Column Plan and Section

10. A column may be classified based on different criteria such as:
1. Based on shape
 Rectangle
 Square
 Circular
 Polygon
2. Based on slenderness ratio
 Short column, ? ? 12
 Long column, ? > 12
3. Based on type of loading
 Axially loaded column
 A column subjected to axial load and unaxial bending
 A column subjected to axial load and biaxial bending
4. Based on pattern of lateral reinforcement
 Tied columns
 Spiral columns

11. Minimum eccentricity
Emin > l/500 + D/30 >20
Where, l = unsupported length of column in ‗mm‘
D = lateral dimensions of column
Types of Reinforcements for columns and their requirements
Longitudinal Reinforcement
 Minimum area of cross-section of longitudinal bars must be atleast 0.8% of gross section area of
the column.
 Maximum area of cross-section of longitudinal bars must not exceed 6% of the gross cross-section
area of the column.
 The bars should not be less than 12mm in diameter.
 Minimum number of longitudinal bars must be four in rectangular column and 6 in circular
column.
 Spacing of longitudinal bars measures along the periphery of a column should not exceed 300mm.
Transverse reinforcement
 It maybe in the form of lateral ties or spirals.
 The diameter of the lateral ties should not be less than 1/4th
of the diameter of the largest
longitudinal bar and in no case less than 6mm.
The pitch of lateral ties should not exceed
 Least lateral dimension
 16 x diameter of longitudinal bars (small)
 300mm
Helical Reinforcement
The diameter of helical bars should not be less than 1/4th
the diameter of largest longitudinal and not
less than 6mm.
The pitch should not exceed (if helical reinforcement is allowed);
 75mm
 1/6th
of the core diameter of the column
Pitch should not be less than,
 25mm
 3 x diameter of helical bar
Pitch should not exceed (if helical reinforcement is not allowed)
Least lateral dimension
 16 x diameter of longitudinal bar (smaller)
 300mm

12. What are Simply Supported Slabs?
Before we discuss the technical design rules of Simply Supported slabs, lets just go through its
definition and learn why they are named so…
As the name suggests, simply supported slabs are supported on columns or stanchions…
Simply Supported Slab
Simply supported slabs don‘t give adequate provision to resist torsion at corner to prevent corner from
lifting.
The maximum bending moment will be given if the slabs are restrained. But atleast 50% of the tension
reinforcement provided at the mid span should extend to the support. The remaining 50% should
extend to within 0.1Lx or Ly at the support as appropriate.
RCC Slab Design depends on the on the dimensions of the slab after which the slab is termed as a one-
way slab or a two-way slab…
In the design of RCC structures, Column Design and Beam Design are to be done before we start with
RCC Slab Design
…
Basic Rules followed in the design of simply supported Slab
Thickness of slab
l/d ratio should be less than the following:
 Simply supported slab
 Continuous slab, l/d = 26
 Cantilever slab, l/d = 7
In any case of the above, the thickness should not be less than 100mm

13. Effective span
 Distance between centre to centre of support
 Clear span plus effective depth
Minimum main reinforcement
 0.15% gross c/s of slab – for MS bars
 0.12% gross c/s of slab – for HYSD bars
Spacing of main bars
The spacing or c/c distance of main bars shall not exceed following:
 Calculated value
 3d
 300mm
Distribution or Temperature reinforcement
This reinforcement runs perpendicular to the main reinforcement in order to distribute the load and to
resist the temperature and shrinkage stresses.
It should be atleast equal to;
 0.15% gross c/s of slab – for MS bars
 0.12% gross c/s of slab – for HYSD bars
Spacing of distribution bars
The spacing or c/c distance of distribution bars shall not exceed the following
 Calculated area
 5d
 450mm
Diameter of bars
The diameter of the bars varies from 8mm to 14mm and should not exceed 1/8th
of the overall depth of
the slab.
For distribution steel, the diameter varies from 6mm to 8mm.
Cover
The bottom cover for reinforcement shall not be less than 15mm or less than the diameter of such bar.
RCC Beams
RCC beams are cast in cement concrete reinforced with steel bars. Beams take up compressive and add
rigidity to the structure.
Beams generally carry vertical gravitational forces but can also be used to carry horizontal loads (i.e.,
loads due to an earthquake or wind). The loads carried by a beam are transferred to columns, walls,
or girders, which then transfer the force to adjacent structural compression members. In Light frame
construction the joists rest on the beam.

14. Doubly Reinforced Beam
In this article, we are going to discuss types of beam construction and RCC design of Doubly reinforced
beam…
RCC beam construction is of two types:
 Singly reinforced beam
 Doubly reinforced beam
Singly reinforced beam
A singly reinforced beam is a beam provided with longitudinal reinforcement in the tension zone only.
Doubly reinforced beam
 Beams reinforced with steel in compression and tension zones are called doubly reinforced
beams. This type of beam will be found necessary when due to head room consideration or
architectural consideration the depth of the beam is restricted.
 The beam with its limited depth, if reinforced on the tension side only, may not have enough
moment of resistance, to resist the bending moment.
 By increasing the quantity of steel in the tension zone, the moment of resistance cannot be
increased indefinitely. Usually, the moment of resistance can be increased by not more than 25%
over the balanced moment of resistance, by making the beam over-reinforced on the tension side.
 Hence, inorder to further increase the moment of resistance of a beam section of unlimited
dimensions, a doubly reinforced beam is provided.

15. Besides, this doubly reinforced beam is also used in the following
circumstances:
 The external live loads may alternate i.e. may occur on either face of the member.
For example:
 A pile may be lifted in such a manner that the tension and compression zones may alternate.
 The loading may be eccentric and the eccentricity of the load may change from one side of the
axis to another side.
 The member may be subjected to a shock or impact or accidental lateral thrust.
Design procedure for doubly reinforced beam
Step 1
Determine the limiting moment of resistance for the given c/s(Mulim) using the equation for singly
reinforced beam
Mulim = 0.87.fy.Ast1.d [1 – 0.42Xumax]
Or
Balanced section
Ast1 = (0.36.fck.b.Xumax)/(0.87fy)
Step 2
If factored moment Mu > Mulim, then doubly reinforced beam is required to be designed for additional
moment.
Mu – Mulim = fsc.Asc (d – d‘) [fsc value from page no. 70]
Step 3
Additional area of tension steel Ast2
Ast2 =Asc.fsc/0.87fy
Step 4
Total tension steel Ast, Ast = Ast1 + Ast2
Reinforced Cement Concrete Slab
 A Reinforced Concrete Slab is the one of the most important component in a building. It is a
structural element of modern buildings. Slabs are supported onColumns and Beams.
 RCC Slabs whose thickness ranges from 10 to 50 centimetres are most often used for the
construction of floors and ceilings.
 Thin concrete slabs are also used for exterior paving purpose.
 In many domestic and industrial buildings a thick concrete slab, supported on foundations or
directly on the sub soil, is used to construct the ground floor of a building.
 In high rises buildings and skyscrapers, thinner, pre-cast concrete slabs are slung between the
steel frames to form the floors and ceilings on each level.
 While making structural drawings of the reinforced concrete slab, the slabs are abbreviated to
―r.c.slab‖ or simply ―r.c.‖.

16. Design of various types of slabs and their reinforcement
For a suspended slab, there are a number of designs to improve the strength-to-weight ratio. In all
cases the top surface remains flat, and the underside is modulated:
 Corrugated, usually where the concrete is poured into a corrugated steel tray. This improves
strength and prevents the slab bending under its own weight. The corrugations run across the
short dimension, from side to side.
 A ribbed slab, giving considerable extra strength on one direction.
 A waffle slab, giving added strength in both directions.
Reinforcement design
 A one way slab has structural strength in shortest direction.
 A two way slab has structural strength in two directions.
These slabs could be cantilevered or Simply Supported Slabs.
Construction
 A concrete slab can be cast in two ways: It could either be prefabricated or cast in situ.
 Prefabricated concrete slabs are cast in a factory and then transported to the site ready to be
lowered into place between steel or concrete beams.
 They may be pre-stressed (in the factory), post-stressed (on site), or unstressed. Care should be
taken to see that the supporting structure is built to the correct dimensions to avoid trouble with
the fitting of slabs over the supporting structure.
 In situ concrete slabs are built on the building site using formwork. Formwork is a box-like setup
in which concrete is poured for the construction of slabs.
 For reinforced concrete slabs, reinforcing steel bars are placed within the formwork and then the
concrete is poured.
 Plastic tipped metal, or plastic bar chairs are used to hold the reinforcing steel bars away from
the bottom and sides of the form-work, so that when the concrete sets it completely envelops the
reinforcement.
 Formwork differs with the kind of slab. For a ground slab, the form-work may consist only of
sidewalls pushed into the ground whereas for a suspended slab, the form-work is shaped like a
tray, often supported by a temporary scaffold until the concrete sets.
Materials used for the formwork
 The formwork is commonly built from wooden planks and boards, plastic, or steel. On commercial
building sites today, plastic and steel are more common as they save labour.
 On low-budget sites, for instance when laying a concrete garden path, wooden planks are very
common. After the concrete has set the wood may be removed, or left there permanently.
 In some cases formwork is not necessary – for instance, a ground slab surrounded by brick or block
foundation walls, where the walls act as the sides of the tray and hardcore acts as the base.
Span – Effective Depth ratios
 Excessive deflections of slabs will cause damage to the ceiling, floor finishes and other
architectural details. To avoid this, limits are set on the span-depth ratios.
 These limits are exactly the same as those for beams. As a slab is usually a slender member the
restriction on the span-depth ratio becomes more important and this can often control the depth
of slab required in terms of the span – effective depth ratio is given by,

17. Minimum effective depth = span/(basic ratio x modification factor)
The modification factor is based on the area of tension steel in the shorter span when a slab is singly
reinforced at midspan, the modification factors for the areas of tensions and compression steel are as
given in the figure 2 and 4 of the code.
Solid Slab spanning in two directions
 When a slab is supported on all four of its sides, it effectively spans in both directions, and it is
sometimes more economical to design the slab on this basis. The moment of bending in each
direction will depend on the ratio of the two spans and the conditions of restraint at each
support.
 If the slab is square and the restraint is similar along the four sides, then the load will span
equally in both directions. If the slab is rectangular, then more than one-half of the load will be
carried in the shorter direction and lesser load will be imposed on the longer direction.
 If one span is much longer than the other, a large portion of the load will be carried in the shorter
direction and the slab may as well be designed as spanning in only one direction.
 Moments in each direction of span are generally calculated using co-efficients which are
tabulated in the code.
 The slab is reinforced with the bars in both directions parallel to the spans with the steel for the
shorter span placed farthest from the natural acis to five the greater effective depth.
 The span-efective depths are based on the shorter span and the percentage of the reinforcement
in that direction.
Construction of Sunken Slabs | Building Construction
Sunken slabs are used in the toilets, bathrooms and washing place where we have our washing
machines. The purpose of having a sunken slab is to conceal all the pipes below the floor. Since the
pipes that carry water are concealed below the floor, care has to be taken to avoid leakage problems.
It is seen that people are not much aware of the idea of waterproofing the Sunken slab before the floor
finish is done. In this article, we will discuss the method of the construction of Sunken slab and
waterproofing technique.
Method of construction of a Sunken Slab
 The concrete of the R.C.C. (floor and sunken slab) should mixed with a waterproofing material to
get a denser, watertight concrete.
 Then cement and waterproofing material should be diluted in water and splashed onto the RCC
sunken slab. Over that a layer of plaster should be provided using a mortar plasticizer with the
cement mortar.
 Brick laying of walls and plastering (prior to tiling) of the walls and floor should be done with
cement mortar mixed with a mortar plasticizer.
 Tile fixing for the floor and walls tiles should be done with non-shrink, waterproof tile adhesives
to make the tiled area waterproof.
 Sanitary pipe joints should be sealed with sealants specially manufactured for Sealing Sanitary
joints firmly so that no water can leak through.

18. How to calculate the total load on the footing? |
Building Construction
This article is on request from my readers. Engineering students generally get confused when it comes
to calculating loads for footings. They ask weird and inappropriate questions regarding the load
calculations. This is because they haven‘t understood what loads are to be calculated when
footing/foundation for a building is designed.
Calculation of loads is extremely simple. I hope after reading this article, the queries of many of my
readers would get a satisfactory answer.
Four loads are to be considered in order to measure total load on the
footing:
1. Self load of the column x Number of floors
2. Self load of beams x Number of floors
3. Load of walls coming onto the column
4. Total Load on slab (Dead load + Live load)
If you get well versed with load calculations, then calculating the size of the footing and following the
procedure for foundation design wouldn‘t be a problem
Foundation Design
Foundation is the base of any structure. Without a firm foundation, the structure cannot stand. That is
the reason why we have to be very cautious with the design of foundations because our entire structure
rests on the foundation.
Laying of Column Footing Reinforcement
The strength of the foundation determines the life of the structure. As we discussed in the earlier
article, design of foundation depends on the type of soil, type of structure and its load.On that basis,
the foundations are basically divided into Shallow Foundations and Deep Foundations.

19. In this article, we are going discuss the step by step guide to Column Footing Design….
Reinforced Concrete Footings
Footing comprises of the lower end of a column, pillar or wall which i enlarged with projecting courses
so as to distribute load.
Footings shall be designed to sustain the applied loads, moments and forces and the induced reactions
and to ensure that any settlement which may occur shall be as uniform as possible and the safe bearing
capacity of soil is not exceeded.
In sloped or stepped footings, the effective cross-section in compression shall be limited by the area
above the neutral plane, and the angle of slope or depth and location of steps should be such that the
design requirements are satisfied at every section.
Design Procedure of Column Footings
Here is a step-by-step guide to Column Footing Design:
Column Footing Plan and Section
Step 1

20. Area required for footing
Square = B = (w+w1)/P0
Where, Po = safe bearing capacity of soil
w1 = self weight of footing
w = self weight of footing
For Rectangle = b/d = B/D
A = b x d
Net upward pressure on the footing
q/p = W/A
Step 2
Bending Moment
Critical section for maximum bending moment is taken at the face of the column
For a square footing,
Mxx = q x B/8 (L – a)2
Mxx = q x L/8 (B – b)2
Myy = q x B/8 (L – a)2
Step 3
To fix the depth of the footing shall be greater of the following:
Depth from bending moment consideration
d =?(M/Qb)
where, Q = moment of required factor
Depth from shear consideration
Check for one way shear
Check for two way shear or punching shear
Critical shear for one way shear is considered at a distance ‗d‘ from face of the column.
Shear force, V = qB [ ½(B – b) d]
Nominal shear stress, Tv = k . Tc
Tc = 0.16?fck

21. Step 4
Check for two way shear
Critical section for two way shear is considered at a distance at a distance d/2 from all the faces of the
column.
SF, V = q [ B2
– (b + d)2
]
SF, V = q [L x B – (a + d)(b + d)]
Nominal shear stress, Tv = V/2((a+d)(b+d)d) ——- {for a rectangle
Tv = V/4((b+d)d) ——- {for a square
Tv = k . Tc
k = 0.5 + ? > 1 ; [? = ratio of sides of the column
Tc = 0.16?fck
Area of steel, Ast = M/(?stjd)
Property Valuation System
Studying Building Estimation and Costing helps us evaluate the value of the property according to its
current market trends. The Value of a property is listed into various different categories such as;
1. Market Value
2. Book Value
3. Capital Cost
4. Capitalized Value
In this article, we are going to discuss different categories under which a property is evaluated
that is Valuation is done.
Market Value
The market value of a property is the amount which can be obtained at any particular time from the
open market if the property is put for sale. The market value will differ from time to time according to
demand and supply.
The market value also changes from time to time for various miscellaneous reasons such as changes in
industry, changes in fashions, means of transport, cost of materials and labour etc.
Book Value
Book value is the amount shown in the account book after allowing necessary depreciations. The book
value of a property at a particular year is the original cost minus the amount of depreciation allowed
per year and will be gradually reduced year to year and at the end of the utility period of the property,
the book value will be only scrap value.

22. Capital cost
Capital cost is the total cost of construction including land, or the original total amount required to
possess a property. It is the original cost and does not change while the value of the property is the
present cost which may be calculated by methods of Valuation.
Capitalized Value of a Property
The capitalized value of a property is the amount of money whose annual interest at the highest
prevailing rate of interest will be equal to the net income from the property. To determine the
capitalized value of a property, it is required to know the net income from the property and the
highest prevailing rate of interest.
Therefore, Capitalized Value = Net income x year’s purchase
Year’s Purchase
Year‘s purchase is defined as the capital sum required to be invested in order to receive a net receive
a net annual income as an annuity of rupee one at a fixed rate of interest.
The capital sum should be 1×100/rate of interest.
Thus to gain an annual income of Rs x at a fixed rate of interest, the capital sum should be x(100/rate
of interest).
But (100/rate of interest) is termed as Year‘s Purchase.
Capital Sum = Annual income x Year’s Purchase
The multiplier of the net annual income to determine the capital value is known as the Year‘s Purchase
(YP) and it is useful to obtain the capitalized value of the property.
Building Estimation and Costing
Building Estimation and Costing is a vital part of Civil Engineering. No project can begin without the
total Building Estimation and Costing done by the Engineer. The entire Cost of construction and the
infrastructure used for the purpose of construction is estimated and the final costing is done on the
basis of which a certain percentage of the Project cost is paid to the Engineer, the Architect and other
consultants involved in the project.Valuation is one such important part of Building Estimation and
Costing. Valuation is done after the project is complete on the latest trends of the land prices in the
market.
In this article, we will discuss what is Valuation and the six important purposes of Valuation.
Valuation
Valuation is the technique of estimating and determining the fair price or value of a property such as a
building, a factory or other engineering structures of various types, land etc.

23. Six important Purposes of Valuation
The main purpose of valuation are as follows:
Buying or Selling Property
When it is required to buy or sell a property, its valuation is required.
Taxation
To assess the tax of a property, its valuation is required. Taxes may be municipal tax, wealth tax,
Property tax etc, and all the taxes are fixed on the valuation of the property.
Rent Function
In order to determine the rent of a property, valuation is required. Rent is usually fixed on the certain
percentage of the amount of valuation which is 6% to 10% of valuation.
Security of loans or Mortgage
When loans are taken against the security of the property, its valuation is required.
Compulsory acquisition
Whenever a property is acquired by law; compensation is paid to the owner. To determine the amount
of compensation, valuation of the property is required.
Valuation of a property is also required for Insurance, Betterment charges, speculations etc
RCC Specifications
 Shuttering shall be done using seasoned wooden boards of thickness not less than 30mm.
 Surface contact with concrete shall be free from adhering grout, nails, splits and other defects.
 All the joints are perfectly closed and lined up.
 The shuttering and framing is sufficiently braced.
 Nowadays timber shuttering is replaced by steel plates.
 All the props of approved sizes are supported on double wedges and when taken out, these
wedges are eased and not knocked out.
 All the framework is removed after 21 days of curing without any shocks or vibrations.
 All reinforcement bars conform IS specifications and are free from rust, grease oil etc.
 The steel grills are perfectly as per detailed specifications.
 The covers to concrete are perfectly maintained as per code.
 Bars of diameter beyond 25mm diameter are bent when red hot.
 The materials proportion should be as per the specifications of the concrete.
Number of Cement bags required for a specific cement concrete ratios
 For cement concrete of ratio 1:1:2(1 cement:1sand/coarse sand:2graded stone aggregate) require
11no bags of 50kg.
 For cement concrete of ratio 1:1.5:3 require 7.8no bags of 50kg.

24.  For cement concrete of ratio 1:2:4 require 6 no bags of 50kg.
 For cement concrete of ratio 1:3:6 require 4.25no bags of 50kg.
 For cement concrete of ratio 1:4:8 require 3.2 no bags of 50kg.
 For cement concrete of ratio 1:5:10 require 2.50 no bags of 50kg.
 For cement concrete of ratio 1:6:12 require 2.25 no bags of 50kg
Methods to calculate Property Depreciation | Building Costing
and Estimation
Depreciation is the gradual exhaustion of the usefulness of a property. This may be defined as the
decrease or loss in the value of a property due to structural deterioration, life wear and tear,
decay and obsolescence.
Methods of Depreciation
Four Methods for calculating depreciation
1. Straight line Method
2. Constant percentage method
3. Sinking Fund Method
4. Quantity Survey Method
Straight Line Method
In this method, it is assumed that the property losses its value by the same amount every year. A fixed
amount of the original cost is deducted every year, so that at the end of the utility period, only the
scrap value is left.
Annual Depreciation, D = (original cost of the asset – Scrap Value)/life in
years
For example, a vehicle that depreciates over 5 years, is purchased at a cost of US$17,000, and will
have a salvage value of US$2000, will depreciate at US$3,000 per year: ($17,000 ? $2,000)/ 5 years
= $3,000 annual straight-line depreciation expense. In other words, it is the depreciable cost of the
asset divided by the number of years of its useful life.

25. Constant Percentage Method or Declining balance Method
In this method, it is assumed that the property will lose its value by a constant percentage of its value
at the beginning of every year.
Annual Depreciation, D = 1-(scrap value/original value)1/life in year
Sinking Fund Method
In this method, the depreciation of a property is assumed to be equal to the annual sinking fund plus
the interest on the fund for that year, which is supposed to be invested on interest bearing investment.
If A is the annual sinking fund and b, c, d, etc. represent interest on the sinking fund for subsequent
years and C = total original cost, then –
Sinking Fund Method
Quantity Survey Method
In this method, the property is studied in detail and loss in value due to life, wear and tear, decay,
obsolescence etc, worked out. Each and every step is based is based on some logical grounds without
any fixed percentage of the cost of the property. Only experimental valuer can work out the amount of
depreciation and present value of a property by this method.
Design of RCC Structures
The design of the components of the RCC structure can be done in the following two ways:
1. Working Stress Method
2. Limit State Method
In this article, we are going to discuss the major difference between the two important
methods of RCC design. This will help us understand the mechanics of the Structural Design
and which method is to be adopted for better efficiency.

26. Working Stress Method
 The Stresses in an element is obtained from the working loads and compared with permissible
stresses.
 The method follows linear stress-strain behaviour of both the materials.
 Modular ratio can be used to determine allowable stresses.
 Material capabilities are under estimated to large extent. Factor of safety are used in working
stress method.
 The member is considered as working stress.
 Ultimate load carrying capacity cannot be predicted accurately.
 The main drawback of this method is that it results in an uneconomical section.
Limit State Method
 The stresses are obtained from design loads and compared with design strength.
 In this method, it follows linear strain relationship but not linear stress relationship (one of the
major difference between the two methods of design).
 The ultimate stresses of materials itself are used as allowable stresses.
 The material capabilities are not under estimated as much as they are in working stress method.
Partial safety factors are used in limit state method.
Design of Shear Reinforcement in a beam
The beam is failed by the diagonal tension in which the cracks start from support and extend upto a
distance equal to effective depth and making an angle more or less than 45 degrees.
Design of Shear reinforcement in a beam
A reinforced cement concrete beam 300mm wide and 500mm effective depth is subjected to a
shear force of 40KN at the ends. The beam is provided with 6 bars of 20mm diameter of which 3
bars are cranked at 45 degrees. Design the shear reinforcement for M20 grade concrete.
Here are the steps for the design of Shear Reinforcement in a beam:
Width of the beam = b = 300mm
Shear force = Vu = 40KN

27. Effective depth = d = 500mm
Area of steel, Ast = 3 x 3.14/4 x 20 x 20 = 942.47 mm2
Step one
Nominal shear stress
Tv = Vu/bd
Tv = 40 x 1000/(300 x 500) = 0.26N/mm2
Step two
Percentage of steel
Percent steel = Ast/bd x 100
Percent steel = (942.47 x 100)/ (300×500)
= 0.63%
Step three
As per IS: 456: 2000
Tc = 0.48 + (0.56-0.48)/(0.75-0.5) (0.63 – 0.5)
Tc= 0.52 N/mm2
Therefore, Tv < Tc
No shear reinforcement required.
Step four
Provide minimum shear reinforcement;
As per IS : 456 : 2000
Asv/bsv = 0.4/(0.87 fy)
Assuming 6mm diameter, 2 – legged stirrups
Asv = (2 x 3.14 x 6 x 6)/4 = 56.54 mm2
Sv = (0.87fy.Asv)/0.4b
Sv = (0.87 x 250 x 56.54)/(0.4×300) = 102.47mm say 100mm
As per IS:456:2000,
Maximum spacing = 0.75d

28. = 0.75 x 500
= 375mm
Provide 6mm diameter, 2-legged stirrups@100mm c/c.
Maximum spacing = 0.75d
= 0.75 x 230 = 172mm
Provide 6mm diameter 2-legged stirrups @ 100mmc/c