Conduits | Building Construction

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Construction of Conduits | Civil Engineering

In the previous article, we discussed “Types of Underground Conduits”. Now we will proceed with our discussion on “Construction of Conduits”.

Underground conduits can also be termed as buried conduits. They are constructed in variety of shapes with different materials used for construction.

Load on the conduit

The characters of the conduit determine the load withstanding capacity of the conduit. They are as follows:

  • Material of the conduit
  • Shape
  • Type of the support

For example:

If we take the example of a concrete conduit (rigid material), the load that the concrete conduit can withstand would depend on the following:

  1. Strength of the concrete pipe
  2. Quality of the foundation bedding

How to determine the strength of the conduit?

A three edge bearing test has to be conducted in order to determine the strength of the conduit.

Three edge bearing test
Three edge bearing test

This test simulates a very severe loading condition which would rarely occur in the actual conduits. This helps us determine the maximum load the conduit can take. It has been seen that the conduits can take greater load than that obtained in the test.

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Types of Underground Conduits | Civil Engineering

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Underground Conduits

What are conduits?

Conduits have different meanings in different subjects.

For example:

Geographically, conduits could refer to a channel carrying water, underground tunnel or waterway (river or canal).

In terms of electrical systems, it may refer to an electrical conduit, HVAC (duct) etc.

Electrical Conduits
Electrical Conduits

We are referring to the conduits which is laid underground and used for variety of purposes.

For example:

  • Sewers
  • Drains
  • Culverts
  • Water mains
  • Gas lines
  • Electrical cables
  • Telephone lines

Construction of Earth Tunnels | Building Construction

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How to construct Earth Tunnels?

In this article, we will discuss the procedure of the construction of the Earth Tunnels in a stepwise manner. It will be useful to you all in understanding and remembering the procedure.

We would be studying the construction method of tunnel in two types of soils:

  1. Firm soil
  2. Soft soil

Step1:

Excavation of the ground from below. It is similar to the process used in mining.

Step2:

Check the type and bearing capacity of soil. The method of construction would depend upon the ability of soil to support itself temporarily during construction.

It also depends on the ability of the soil to withstand the magnitude of pressure imposed on it during construction.

Construction of Earth Tunnel
Construction of Earth Tunnel

Step3:

It is important to understand the factors that affect these parameters. They are as follows:

  1. Depth of the tunnel
  2. Diameter of the tunnel
  3. Properties of the soil
  4. Ground water table

Support to the Tunnel

Most of the time, the tunnel requires temporary support during construction and a permanent support after construction.

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Understanding Load Calculations | Structural Design

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Load Calculations | Design of Buildings

In our earlier article, we discussed “Different types of loads” and their importance in Structural design.

Now we will move on with our further discussion on the following points:

  • Design principle assumption and notation assumed
  • Design Constant
  • Assumptions regarding Design
  • Loads on Beams
  • Loads on slabs

Design principle assumption and notation assumed:

The notations adopted throughout are same as given in IS:456:2000

Density of material used in accordance with reference to IS:857-1987s

Sr.no Material Density
1 Plain concrete 24 KN/m3
2 Reinforced cement concrete 25 KN/m3
3 Flooring material (cement mortar) 1.00 KN/m3
4 Brick masonry 19 KN/m3

Design constant

Using M20 and Fe415 grade of concrete and steel respectively for columns and footings

Therefore:

Fck – i. e. Characteristic strength for M15 – 15 N/mm2

Fck – i. e. Characteristic strength for M15 – 15 N/mm2

Fck – i. e. Characteristic strength for M20 – 20 N/mm2

Fy – i. e. Characteristic strength for steel – 415 N/mm2

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Introduction to the calculation of the loads | Building Construction

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Load Calculations | Types of Loads

Students find it difficult to understand the concept of loads although it is a very simple concept. We are going to write a series of articles on “Load Calculations” and help you all in understanding different types of loads that are to be considered for structural designing and also how to calculate them.

In this article, we will discuss different types of loads with examples.

In our next article, we will cover the following points:

An object is subject to mainly two types of forces:

  1. Live loads
  2. Dead loads

Basically, an object subject to any type of force which could be gravitational force (weight), pressure or anything affects the object is called a load.

This concept is used in Mechanical and structural engineering. Let’s take in terms of Structural Engineering. Whenever a structure is designed, these concepts are taken into consideration because real world objects are analyzed in order to design the structure. This is very important in terms of structural stability.

What are “Dead loads”?

As the name itself suggests, dead loads could be termed as self weight of the non-living objects. It could be the weight of the materials, equipments or any other components in the structure that will remain permanent throughout the life of the structure.

Dead load has to be considered in order to make the structural design accordingly. Dead loads vary from structure to structure. Every building is unique and has different considerations.

An additional load is considered in case additional forces build up in a structure in case of settlement or due to secondary effects of pre-stress construction or due to shrinkage of concrete.

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Fly ash Bricks | Building Materials and Construction

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Fly ash Bricks | An alternative Building Material

Fly ash bricks are masonry units that are used in the construction of buildings. They are considered to be a part of good and affordable building materials. They contain Class C fly ash and water.

Fly ash bricks are made by compressing Class C fly ash and water at 4000psi and then curing is carried on for 24 hours at a temperature of 66 degrees Celsius steam bath. Air entrainment agent is used to toughen the bricks.

Fly ash Bricks
Fly ash Bricks

Since the concentration of calcium oxide is very high in class C fly ash, the brick is described as self cementing.

It is considered to be a good alternative to traditional mud bricks since the method of manufacture of fly ash is energy efficient that is it helps save energy, brings about reduction of mercury pollution and plus it is cost effective.

Raw materials used for the manufacture of Fly ash Bricks:

  • Fly ash – which is the primary ingredient
  • Sand or Stone dust – as fine aggregate
  • Lime – source of calcium carbonate which results in the bricks being called “Self-cementing bricks”.
  • Gypsum – to enhance the fineness of the shape of the bricks
  • Cement – to increase bonding and strength

Types of Bonds in Brickwork | Stretcher and Header Bond

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Bonds in Brickwork | Building Construction

In our previous articles, we discussed “what is a bond?” and “Rules for good Bonding”. Let us start our further discussion on types of bonds.

Different types of bonds are:

  1. Stretcher bond
  2. Header bond
  3. Facing bond
  4. English bond
  5. Flemish bond
  6. Dutch bond
  7. English cross bond
  8. Brick on edge bond
  9. Raking bond
  10. Zigzag bond
  11. Garden wall bond

Now we will proceed with our in depth discussion on “Stretcher bond” and “Header bond”.

What is a Stretcher Bond?

As the name itself suggests, stretcher bond is formed by laying bricks horizontally as stretchers on the faces of walls. The length of the bricks is along the horizontal direction of the wall.

Stretcher bond | Exposed Brickwork of a Restaurant
Stretcher bond | Exposed Brickwork of a Restaurant

Stretcher bond is used when walls of half brick thickness are to be constructed. The average size of the brick is 9cmx9cmx18cm. If the wall of thickness 9cm is to be constructed, then stretcher bond can be used.

Various types of wall constructions are done using this type of bond.

  • Sleeper walls
  • Partition walls
  • Division walls (internal dividers)
  • Chimney stacks

Bonds in Brickwork | Building Construction

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Various types of bonds in Brick work

What is a bond?

When bricks are laid adjacent to each other forming a groove in between the bricks which is filled by cement mortar is called a bond. Bonding helps in even distribution of loads over a large area.

There are various types of bonds. Bricks are arranged in courses in such a way that they are tied together and also care is taken of the vertical joints that are formed when bricks are arranged in courses. The bricks used for the purpose of masonry construction are uniform in size.

Bilbee herring bond
Bilbee herring bond

The rule is, “Vertical joints of the successive courses of bricks should not coincide, that is, a continuous vertical joint across the wall should be avoided since it will gradually result into cracks development.” The strength and stability of the wall is less as compared to the properly bonded brickwork. Improperly arranged bricks forming continuous vertical joints are also called “unbounded walls”.

Like I mentioned earlier, there are various types of bonds; these bonds are distinguished by their appearance which basically means their bonding style (fashion in which bricks interlock to tie themselves together).

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Bending Moment and Fixed Moment Calculations

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Bending Moment and Shear Force diagrams

What is Bending Moment?

The element bends when a moment is applied to it. Every structural element has bending moment. Concept of bending moment is very important in the field of engineering especially Civil engineering and Mechanical Engineering.

Unit of measurement: Newton-metres (N-m) or pound-foot or foot-pound (ft.lb)

Bending moment is directly proportional to tensile and compressive stresses. Increase in tensile and compressive stresses results in the increase in the bending moment. These stresses also depend on the second moment of area of the cross section of the element.

What is Shear stress?

Shear stress is defined as the measure of force per unit area. Shear stress occurs in shear plane. There are many planes possible at any point in a structure which can be defined to measure stress.

Stress = Force/Unit area

Example: Bending Moment and Shear Force Calculations

Frame diagrams | Bending moment and shear force calculations
Frame diagrams | Bending moment and shear force calculations

Simply supported bending moment

Mab = wl2/8 = (22×4.14×4.14)/8

= 47.13 KN-m

Mbc = wl2/8 = (22×4.14×4.14)/8

= 47.13 KN-m

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Types of Construction | Building Construction and Design

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Building Construction | Civil Engineering and Design

Construction of buildings can be divided into three main categories:

  1. Load bearing construction
  2. Composite construction
  3. Framed construction

But among the three types, framed construction is widely used for all kinds of constructions.

An engineering structure is an assembly of number of elements transferring the loads and providing a form space to serve the desired function.

Building Construction and Design
Building Construction and Design

The structural design is a science and art of designing, with economy and elegance, a durable structure is that which can safely carry the forces and can serve the desired function satisfactorily during its expected service life span.

The entire process of structural planning and designing requires not only imagination and conceptual thinking but of practical aspects, such as relevant design codes and byelaws, backed up by aple experience, institution and judgement.

The process of design commences with planning of a structure, primarily to meet the functional equipment of the user or client. The functional requirements and the aspects of the aesthetics looked into normally by an architect while the aspect of safety, serviceability, durability and economy of the structure for its intended use over the life span.

What is a building?

A building can be defined as a structure consisting of walls, floors, education, business, manufacturing, storage, hospitalization, entertainment, worship etc.

Normally all building are constructed according to drawings and specifications prepared by architects. Each city has prescribed building bye-laws to which building must confirm. The building bye-laws lay down norms like minimum front, side and rear backs, minimum height and area of habitable rooms, kitchen, bath, minimum area of windows, width of staircase etc, apart from respecting the bye-laws the building design should ensure optimum utilization of built-up space, thermal comfort, proper ventilation, desirable illumination and acoustical characteristics and it should satisfy the functional requirements of people who live and work in the building.

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