Types of footing pdf

Foundation is the lowermost structure in any building, it will transfer the load from superstructure to the soil substructure.

types of footing pdf

There would have been no need of foundation if the soil is good in shear. The column would have been sufficient. But column punches settles or goes inside soil because of a small perimeter. So, the foundation is provided just to increase perimeter so that load is distributed over a large area. Classification Of Beams. Shallow foundations are those founded near to the finished ground surface; generally where the founding depth Df is less than the width of the footing and less than 3m.

Shallows foundations are used when surface soils are sufficiently strong and stiff to support the imposed loads; they are generally unsuitable in weak or highly compressible soils, such as poorly-compacted fill, peat, recent lacustrine and alluvial deposits, etc. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.

Engineering Insider. Vikas Shukla. Leave a Reply Cancel reply Your email address will not be published. Search for: Search.Most of the structure consist of two parts, one above the ground which is known as super structure and the other sub-structure of the foundation which lies below the ground level.

Types of Reinforcement or Mesh used in Different Footings(Foundations)

Foundation aka footing is defined as that part of the structure that connects and transmits the load from the structure to the ground soil. The solid ground on which the foundation rests is termed as the foundation bed. Every structures are provide with foundation at the base to fulfill the following objectives and purposes:.

Shallow Foundation. Deep Foundation. Factors affecting the selection of Foundation. Foundation are classified on the basis of load transmission to the ground into two sub-categories i. Shallow foundations are generally termed as spread footing as they transmit the load of the super structure laterally into the ground.

This type of foundation runs continuous along the direction of the wall and helps to transmit the load of the wall into the ground.

Wall footing are suitable where loads to be transmitted are small and are economical in dense sands and gravels. In this type of foundation the width is times the width of the wall at ground level.

Wall footing may be constructed through stone, brick, plain or reinforced cement concrete. Column footing are suitable and economical for the depth greater than 1. In this type of foundation the base of the column is enlarged. Column footing is in the form of flat slab and may be constructed through plain or reinforced concrete.

Combined footings are those foundations that are made common for two or more columns in a row. It is used when the footing for a column may extend beyond the property line. It is also suitable when the two columns are closely spaced and the soil on which the structure resist is of low bearing capacity.

It may be rectangular or trapezoidal in shape. When an edge footing cannot be extended beyond the property line the edge footing is linked up with the other interior footing by means of a strap beam. Such footings are called as strap footing. It is also know as cantilever footing. A mat foundation is a combined footing which covers the entire area beneath of a structure and supports all the walls and columns.

It is also known as raft foundation. Mat foundation is applicable when:.There are different types of Reinforcement in footings.

We know that we have to insert reinforcement in Footings for tension requirements. As per B. Datta the percentage of reinforcement in footings is between 0. Type of Mesh used in footings is designed by structural engineer according to load analysis.

Here I am discussing the types of mesh reinforcement adopted in different types of footings or foundations. You can also read 10 Types of footings or foundations which we adopt in Construction. This type of Mesh is usually adopted in Plain or Isolated or combined footings.

This type is generally used in low-rise buildings. In this type, bars are placed as a grid. It may have bars of different diameter and spacing in either direction. The spacing may or may not differs in both directions. This type of mesh is adopted in low rise and as well high rise buildings. The footing is reinforced as grid and at the ends of the mesh, the bars are hooked.

Bending the bars ends helps in the proper anchorage of the reinforcement. Where the hook length is 9D. D is the diameter of the bar. It is similar to Plain footing. In this type, The bars are bent at ends upto a height of footing. This type of Mesh is provided in Raft footing.

Raft footing is adopted when soil bearing capacity is very less.

Types of Foundation

In this type, Mesh is divided into two parts, Top mesh and Bottom Mesh. Firstly, the bottom mesh is provided on covering blocks, ends of a bottom mesh are bent at an angle of 90 degree up to a height of 50D where D is Dia of Bar. And then top mesh is tied to the bottom mesh in reverse direction.Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi adipiscing gravdio, sit amet suscipit risus ultrices eu. Fusce viverra neque at purus laoreet consequa. Vivamus vulputate posuere nisl quis consequat. Footing is one of the most important parts of a structure which transfers loads of a structure to the underlying soil.

The selection of suitable type of footing generally depends on the following factors:. It is a component of shallow foundation which distributes the weight of a load bearing wall across the area of the ground.

It is also known as wall footing. As the name suggests, a spread is given under the base of the foundation so that the load of the structure is distributed on wide area of the soil in such a way that the safe bearing capacity of the soil is not exceeded.

It is square, circular or individually rectangular slab of uniform thickness, provided under each column. The main purpose of using stepped footing is to keep the metal columns away from direct contact with soil to save them from corrosive effect. They are used to carry the load of metal columns and transmit this load to the below ground. When two or more columns are supported by a footing it is called combined footing. This footing may be of rectangular or trapezoidal in plan.

Combined footing is provided under following situations. In such footing, the outer and inner column is connected by a strap beam, does not transfer any load to the soil. The individual footing areas of the columns are so arranged that the C.

G of the combined loads of the two columns pass through the C. G of the two footing areas. Once this criterion is achieved, the pressure distribution below each individual footing will be uniform.

This foundation covers the entire area under the structure. This foundation has only RCC slab covering the whole area or slab and beam together. Mat foundation is adopted when heavy structures are to be constructed on soft made-up ground or marshy sites with uncertain behavior. Mat foundation is also known as raft foundation. The footings having sloping top or side faces are known as sloped footings.

This type of footing is useful in the construction of formwork.Foundation is the most important element of any construction but least understand mechanism. Making minor mistakes causes the whole structure collapse. But the reality is very simple if you read this guide. Obviously, this is not a one stop shop to gain all the knowledge about designing foundation and implementation.

But this comprehensive guide will give you basic knowledge how the design of foundation works and how it supports the whole structure. Before beginning types of foundation. We have a deep sense of responsibility for explaining you the basic mechanism of foundation design. The main function of building elements such as columns, beams is transferring the load stress from slab to beam, beam to the column and then the column to the foundation of the earth soil.

The fun part is that the design people will approach this in a top down level.

WHAT ARE DIFFERENT TYPES OF FOOTINGS?

According to Wikipedia. SBC Safe Bearing Capacity is defined as the capacity of earth soil that supports the load applied to the ground without any shear failure or settlement. It means safe bearing capacity is the maximum average pressure between the foundation and earth soil which should not produce shear failure or settlement.

In Simple, It is the maximum capability of soil to support without any failure or settlement. However, for practical application, we use a factor of safety to find the allowable bearing capacity of the soil. Rules — I want you to play a game where each participant has to hold the maximum number of stumper balls in their hands and have to run metre distance whoever comes first will win the game.

You could able to hold 7 stumper balls Ultimate Bearing Capacity in your hand at once. Now we know how important is to find the Safe Bearing Capacity of soil for the building location. However, the Earth soil must not uniform throughout. So we invite Geotechnical Engineers to examine the earth soil. They will examine the earth soil layers using different types of sampling method and tests along with other details such as water table. Once they finish the examination, they will analyse the soil at the lab and conduct different types of tests to find the real capacity of the soil.

They give us the detailed conditions of the earth soil layer and suggest which type of foundation we could use at this location. Based on this, designer will start to design the building foundation.

Generally, there are two broad categories of types of foundation. This types of Foundation mostly built for lightweight buildings where the condition of the soil is extremely good with uniform layer and low water table.

Shallow foundations also referred as spread footings or open foundation since the earth soil will be completely removed to construct the footing and later filled by backfilling. It is referred as Spread footing because the footing base width is wider than the typical load bearing wall. It is the most common type of foundation widely used for buildings. These foundations connected with plinth beam just below the ground level. It comes in various shapes such as rectangular, circular and continuous according to the load distribution.

Note — You can get a rough idea of the foundation shape using SBC of soil. You can also design different geometrical shapes of foundation such as circular, square or rectangular. There are no limits. Also, You can find the Safe Bearing Capacity of soil in this method if you know the column load. Sometimes two or more footing may be combined because the adjacent footing might be closer where shuttering is not possible at all for the given procedure like below one. Strip foundations are continuous footing which will be constructed at the load bearing masonry construction where walls will be acted as load bearing structure.

The footing will be constructed continually under the walls to support the load developed on the walls. These types of footings constructed in old masonry construction still these are in existence in local construction.Following are the types of shallow foundations: 1. Spread Footing 2.

What Is Foundation And Its Types – Civil Engineering

Combined Footing 3. Raft Foundation 4. Annular Slab or Ring Foundation. Foundation which spreads the load from a wall or column to a greater width is known as spread foundation or footing.

The spread footing provided to the walls of a load bearing structure is known as wall footing, continuous footing, or strip footing. Spread footing may also be stepped footing as shown in Fig. Strip footing, shown in Fig. Strip footing constructed of stone masonry usually has a stepped cross section, similar to the one shown in Fig.

With the development of concrete, however, both load bearing structures and strip footings have become more or less obsolete, except for small lightly loaded residential buildings. It is also known as continuous footing or wall footing.

Spread footing provided to the columns of a framed structure is called isolated footing, column footing, or pad foundation. Square column foundations, shown in Fig. Circular footing, shown in Fig. For unequal column loads, trapezoidal footing, shown in Fig. For footings situated near property lines, a strap footing, as shown in Fig.

In this case, the footing near the property line exterior footing is connected to the footing inside the site interior footing through a strap beam.

types of footing pdf

The strap beam transfers the load of the exterior column footing partially to the interior footing through structural action. A raft foundation also called as mat foundation is also provided for heavy structures located over highly compressible and weak soils extending to large depth. The plan and section of a raft foundation is shown in Fig.

A ring foundation is sometimes provided for a large water tank with its columns connected through a ring beam and supported over an annular slab, as shown in Fig. If a good bearing stratum of soil or rock is available at a shallow depth, a shallow foundation is the first choice as it is more economical and is always preferred to a deep foundation.

The following are the advantages of shallow foundations when compared to deep foundations:. Construction of shallow foundations is simple as the depth involved in laying the foundation is less. The equipment required for the construction of shallow foundations is simple and less costly. Shallow foundations can be constructed in a short time, which would further help in reducing the cost of hiring equipment and labor. The quantum of soil investigation required for shallow foundations is less because the pressure bulb extends to less depth as compared to deep foundations.

For deep foundations as the depth of soil involved is more, the uncertainty is also more. The settlement of shallow foundations may be more and requires careful consideration.

types of footing pdf

Otherwise, the structure may undergo damage or failure. In the case of deep foundations, when taken to hard stratum, the settlement of foundation and hence of structure may be less.

A deep foundation is adopted only when a shallow foundation cannot be provided.Foundation or Footing is the most important and basic part of a structure. There are different types of foundations that function as to transfers loads of a structure to the underlying soil.

The isolated footing is commonly used in reinforced cement concrete columns because it very is simple and most economical as compared to the other footings. The isolated footings are independent footings for every column and provided for each column separately in buildings. In spread footing, spread bars are provided under the column and Wall base. So that the load of the structure is distributed on the wide-area of the soil in such a way that the safe bearing capacity of the soil is not exceeded.

Normally footing having the sloping top or side faces. The isolated sloped footing is used to distribute the load evenly from columns to the soil. The main function of the strap footing was to help in the distribution of the weight either heavily loaded column as well as the eccentrically loaded column. This type of footings is provided because of these situations if.

Mat foundation is used when heavy structures are going to be constructed on soft ground or marshy sites. The mat foundation covers the entire area under the structure.

Types of Footing – Building Construction Foundation

The mat foundation is also known as the raft foundation. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Now Trending: Mosaic Tiles — Its Weight of concrete per c Contents 1 Types of Foundations 1.

Adegboro m. Samuel June 17, Reply. This is really a tutorial class.


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