Design of RCC structures

Calculations for Overhead Water tank | Building Construction

November 6, 2011 by Designer

Design of Overhead Water Tank | Design of RCC Structures

As per NBC (National Building Code, 2005) standards,

Water required per person per day = 150 litres

Drinking water = 4litres per person per day

Calculation for an overhead water tank for a 3 BHK Villa:

Let us assume the average family size = 5 persons in the house

Water required for daily chores per person per day as per NBC norms;

150 x 5 = 750 litres

Drinking water required:

4 x 5 = 20 litres

Total quantity of water required = 750+20 = 770 litres

Volume of water = 770/1000 = 0.77 cubic metres

Consequences of Wrong Structural Design | RCC Structures

October 29, 2011 by Designer

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.

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.

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.

Minimum Standards for Structural Design | RCC Structures

October 9, 2011 by Designer

Thumb rules for Structural Design | RCC Structures

I highly recommend use of advanced structural design software like ETabs or Staad Pro for design of structures. This is very important. There are so many variables in design of a structure that no minimum standards can be accurate. This guide can be used for design of very small structures, maybe up to G+1 floors. But I would still recommend use of professional software. Every structural designer should learn these software. Use of manual methods is outdated. Manual method is only used for checks. Real design is done with the help of computers, with very advanced design concepts like pushover analysis, seismic analysis, wind loads simulation and many advanced methods.

You can hire me for your structural design need. Contact me.

Design of RCC Structural Components

In this article, I will discuss the minimum standards that can be followed for the design of RCC structural components of a structure, such as columns, beams, slab and foundation. We will also discuss the minimum safe standards for the reinforcing bars that are to be used for the design of the above mentioned Structural Components.

Minimum cross-sectional dimension for a Column: is 9″x 12″ (225 MM x 300 MM) which is the minimum recommended size. I have designed hundreds of buildings, and never had the misfortune of any structural component ever failing due to loads. I always use M20 grade concrete for construction, as it is the minimum recommended grade of concrete is IS 456:2000. Please don’t skimp on the quality of concrete. The minimum steel in a 9″ x 9″ column is 4 bars of 12 MM with stirrups of 8 MM steel rings at a distance of 150 MM centre to centre. In a 9″ x 12″ column, I add two more bars, to take the total to 6 bars of 12 MM diameter. This design can be safe for up to G+1 floors. But there are a lot of other factors involved.

Also check out:

Thumb rules for making a Column Layout

Construction on Site | Design of RCC Structures

Construction on Site | Design of RCC Structures[/caption]

Minimum RCC beam size should not be less than 9″x 9″ (225MM X 225MM), with an additional slab thickness of 125 MM. I generally use a minimum of 4 bars, with 2 bars of 12 MM thickness in the bottom of the beam, and 2 bars of 10 MM at the top of the beam. I maintain a concrete cover of 40 MM. I recommend use of M20 grade of concrete (1 part cement : 1.5 parts sand : 3 parts aggregate : 0.5 parts water).

Minimum thickness of RCC slab I recommend is 5″ (125MM) because a slab may contain electrical pipes embedded into them which could be 0.5″ or more for internal wiring, which effectively reduces slab depths at certain places, causing cracking, weakening and water leakage during rains. So, a minimum thickness of 5″ should be maintained.

RCC Building Design and Construction | Structural Design

August 4, 2011 by Designer

Step by step procedure to RCC building design | Design of RCC Structures

A building is composed of various structural components such as Foundations, Plinth beams, Columns, Beams, Slab, Staircase, Doors and Windows.

Design of Foundation | RCC Building Design

Foundation design is the structural component from where the RCC design is initiated. The foundation design guide discussed earlier includes in detail the design procedure for isolated column footing. Column footing is the most commonly used type of foundation. It serves a variety of different buildings.

Design of Foundation – the most commonly used foundation is Column footing.
Calculation of loads in Foundation Design Calculation of loads is very important for the purpose of structural design. This article outlines the thumb rules for the calculation of various loads in foundation design.
Types of Foundations This is a generic article on different types of foundations. It covers some commonly used shallow foundations and also explains pressure distribution under a foundation.

Design of Beams | RCC Building Design

Beams are mainly classified into two types:

Doubly reinforced beam (most commonly used in RCC Construction)
Singly reinforced beam
A series of articles have been written for the design of Singly reinforced sections. The articles include basic definitions and formulas, understanding stresses and modular ratios, assumptions for singly reinforced sections, Design method 1, Design method 2, Moment of resistance and a number of solved numerical examples.

Design of Columns | RCC Building Design

Design of RCC columns

The article discusses the classification criteria for a column, and design of different types of reinforcements for columns which include longitudinal, transverse and helical reinforcements.

Thumb rules for designing a Column Layout

The articles important thumb rules to be followed for column layout design. Three important thumb rules have been discussed.

Size of the Columns
Distance between Columns
Alignment of columns

Continuous Beams | Design of RCC Structures

July 10, 2011 by Designer

Design of Continuous Beam | RCC Structures

Definition

The beam that rests on more than two supports. The beam that rests over multiple columns. Continuous beams increase the structural rigidity of a structure. They offer alternate load path incase of a failure of a section in the beam.

Continuous beams are commonly used in buildings in seismic risk zone.

Three moment equation or Clapeyron’s equation

Four Methods for Analysis of a beam are as follows:

Three moment equation
Moment distribution method
Kani’s method
Slope deflection method

Introduction to Design of RCC Structures

November 16, 2010 by Designer

RCC structures

RCC (Reinforced Cement Concrete) is a construction technology which evolved with the evolution of different structural materials in the 18th century during the Industrial Revolution.

Industrial Revolution brought in new technology which helped in the manufacture of various materials. The Architect Le Corbusier used RCC for various constructions. He believed that any shape and form was possible; if RCC is to be used.

For example, Notre Dame Du Haut, Ronchamp, France

This is an example of Le Corbusier Project where he used RCC like plastic.

Notre Dame Du Haut, Ronchamp, France | RCC Structures

What is RCC?

RCC means Reinforced Cement Concrete, i.e., cement concrete reinforced with steel bars, steel plates, steel mesh etc to increase the tension withstanding capacity of the structure.

Cement Concrete can take up immense compression but weak in tension whereas steel is good in withstanding both tension and compression.

Guide to Design of Shear Reinforcement in a beam

October 14, 2010 by Designer

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.

Shear reinforcement diagram (beam longitudinal section)

Here are the steps for the design of Shear Reinforcement in a beam:

Step one

Nominal shear stress

Tv = Vu/bd

Where, Vu = shear force due to design load

b = width of the beam

d = depth of the beam

Step two

Percentage of steel

Percent steel = Ast/bd x 100

Differences between Working stress method and Limit state method

October 14, 2010 by Designer

The design of the components of the RCC structure can be done in the following two ways:

Working Stress Method
Limit State Method

Here are some of the design procedures of the components of the RCC structures:

Design of RCC beams

Design of RCC columns

Design of RCC staircase

Design of Foundations

Design of Simply Supported Slabs

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.

Read more

Guide to Design of Simply Supported Slabs | Design of RCC Structures

May 28, 2010 by Designer

What are Simply Supported Slabs?

Simply supported slabs are supported on columns or stanchions. They have support on all four sides.

Simply supported slabs are classified as One way slabs and Two way slabs.

One way slabs bend in one direction only and transfer their loads to the two support beams in opposite directions. Their main steel in on shorter span length. L/B ratio is generally less than 2.

oneway

Two way slabs bend in both directions, and transfer their loads and stresses on all four sides. L/B ratio is equal to or greater than 2.

twoway

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.

You can use a free app to design simply supported RCC Slab panel.

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…

Staircase Design | RCC Structures

May 18, 2010 by Designer

RCC Staircase Design

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 dog-legged reinforced cement concrete staircase design.