Category: ENGINEERING ARTICLES

This section contains engineering interresting articles

Introduction to BIM (Building Information Modeling)

Introduction to BIM (Building Information Modeling)

 

BIM is not a new concept

 

BIM is not a new idea or a new concept, it has been with us for many years now.

The developments in technology have enabled the construction industry to plan design construct and manage more complex and larger scale projects every year more and more.

Professionals in architecture, architectural technology, building surveying, quantity surveying, construction management and property development and planning are planning BIM increasing the efficiency of projects, improving collaboration between different stakholders and creating a central model that contains all the project information or only some of the added values of implementing BIM.

So what is BIM ?

 

 

What is BIM?

 

« BIM is evolution not revolution », it was developed over many years by various scholars from all over the globe who worked hand-in-hand with software developers.

The first BIM concept that appeared on PCs was in 1984. Two years later in 1986 Robert Ash introduced the term Building Modelling for the first time. Building performance data on early BIM applications in 1993. The golden years of BIM development were from late 1990’s to early 2000’s.

In 2004 collaboration on central models appeared on BIM applications the advancements of being accelerated considerably from that point and in 2008 more cutting-edge technologies such as parametric modelling and laser scanning were incorporated into BIM applications.

After 2015, different goverments made amendments to the existing construction regulations to imporve the incorporation of BIM process. For example in 2016, the use of BIM process in funded projects became mandatory in the UK. In 2020, Germany made it compulsory for transportation projects to use the BIM process.

 

While there are different definitions of BIM, it is a process that improves collaboration between different stakeholders throughout building’s lifecycle.

BIM is a process of working together to advance th efficiency of construction projects.

The most important element of a BIM process is a BIM model that contains all building information.

So here are two important questions :

  • What can we do with a building model ?
  • What building information can be integrated into a digital model ?

The answer to both questions is everything.

A BIM model includes a detailed 3D Model with all architectural and structural elements, mechanical and electrical systems, spaces details schedules and all sort of documentations.

It can easily calculate cost estimation, material quantities, energy performance, etc…

 

 

Is BIM only useful for large and complex projects ?

 

Absolutly not, implementing BIM is highly beneficial for fifferent types of projects with various functions and scales.

Scan to BIM for real-time surveying and incorporation of site features create a huge potential to design and construct spaces that are perfectly integrated with various site-specific conditions.

Implementing BIM will also increase project precision and accuracy less errors and mistakes. It will also improve the coordination between different disciplines involved in a project which would eventually result in minimizing time and cost of the projects.

Using BIM, we can have planned overlaps within different stages of the project which results in reducing the project time and cost.

 

Effects of BIM on Project Lifecycle

 

Issues before implementation of BIM

 

  • Incompatible ID systems,
  • lots of problems around file sharing and different file formats,
  • extensive use of paper email overload as more conversations were required among different stakeholders.
  • Low data scurity and unclear modern date ownship
  • low transparency of information flow and of reversion documents
  • limited project records
  • No central model containing all project information

 

Using one system of digital models increases the synchronization between various documents produced by different professionals involved in a project. BIM is the process of designing constructing and manaing a building or infrastructure collaboratively using advanced length digital models.

 

 

 

 

Basic IFC Concepts for Revit users

Basic IFC Concepts for Revit users

 

What is IFC and why it is often misunderstood ?

 

IFC is developed by the buildingSMART association and it is an open standard for the BIM Data exchane.

IFC stands for the Industry foundation classes and it’s not a file format, but actually a semantic schema which defines the way the building related data is described and inherited.

This also means that you can open an IFC file in a simple Texteditor and view its content.

The foundation of IFC are as its name already says the classes, which can describe anything, from a physical object like a wall to abstract concept like a task.

Unfortunately the buildingSMART documentation is very complicated and even scary, because it is actually meant for software developers and not for us mortal Revit users. But the good thing is that you don’t need to get that deep into the theory in order to be able to uses IFC correctly.

 

Using the IFC documentation

 

Now let’s have a look you can find and navigate the IFC documentation. You can always access the latest version through the buildingSMART wbsite at https://technical.buildingsmart.org/

As you can see here, IFC4 is the latest development and it is also still being updated.

IFC2x3 is also still often used, but we will stick with IFC4 in this video series, because it is the latest development and 2×3 will become more and more obsolete in the next years.

The best way to find the IFC classes is to select alphabetical listing from the main page sinc IFC4 we can also browse the list in other languages like German, or also in plain English.

Keep in mind that there are a lot more IFC classes that Revit categories for two reasons : the first one is that IFC classs are often more granular and the second one there are many classes which don’t describe physical elements or don’t have a representation in a BIM modeling software like Revit.

Another important point are the predefined property sets – all of the common property sets are mapped automatically when exporting from Revit.

These are very important because they provide the most important element information in a standardized way, and are always structured and named in the same way, no matter from which software the model has been exported.

Same goes for the Quatity sets, which are a special kind of the property sets are used for QTO workflows.

 

IFC Mapping table in Revit

 

You can find the mapping table if you go to Revit -> Export Settings -> IFC. This table displays the Revit Categories matched to IFC classes and types.

Note that this table is already filled out by default and it should cover the most common usecases but of course you can always change it if needed.

For this, you will need to copy and paste the exact name from the IFC documentation. Certain Revit categories can also be excluded from the export by simply inserting Not Exported.

This is just the starting point, as in most BIM Projects you will need a more granualar mapping on the object level. The mapping table is saved as a simple textfile and can be easily shared.

If you ever want to revert the default settings or of the mapping table gets messed up by switching between different Revit languages, you can reset it very easily select Load, delete the default file and then hit « Standard ». This will regenerate the file you just deleted with the default, hardcoded settings.

Once we have set up the mapping table, you can launch the Export dialog. Here y ou can select between several already pre-defined setups or also modify these.

 

Model View Definitions (MDV)

 

Note that the IFC schema is always combined with a Model View Definition or MVD, which defines a subset of the IFC schema. You can compare an MVD with a 3D view in Revit, where all elements from all phases, all analytical models and calculations are all displayed at the same time.

Model View Definitions help to extract the data in a meaningful way, like a dedicated view of the model.

This is very simplified explanation, but you get the point !

If you use IFC2x3, your choice will usually be the Coordination View 2.0, and for IFC4 the Reference View. These are the default MVDs defined by the buildingSMART for BIM coordination.

 

Open source Revit IFC

 

The client of the BIM Manager should always define which IFC version and which MVD is to be used in a project in order to keep this consistent.

Otherwise, just use IFC4 Reference View for your specific discipline. It is important to keep in mind that Autodesk offers an open source Revit Toolset and regularly updates IFC for Revit independantly from Revit Updates.

This way the developers can react much faster and publish updates whenever needed. Therefore you should keep an eye on the version number and check back on apps.autodesk.com for updates.

The easiest way is to just search for revit IFC and you will be presented with the apps for the four most current Revit versions.

Often you will find these updates a week or two earlier on github, where the developers are also publishing the sourcecode, but you can also download the most current installers here.

 

Current download links for Revit IFC (sidebar): https://bim-me-up.com/​

Autodesk App Store: https://apps.autodesk.com​

Revit IFC on Github: https://github.com/Autodesk/revit-ifc​

Wiki OS with useful tips around openBIM, not only for Revit: ​ https://wiki.osarch.org/index.php?title=Category%3AAutodesk_Revit

Recommended freeware IFC Viewers:

Open IFC Viewer, very fast and supports latest IFC Versions: https://openifcviewer.com/​

BIM Vision, powerful viewer, offers additional features for measurement or easy display of classifications: https://bimvision.eu/download/​

BIMcollab IFC Viewer, popular viewer, offers direct connection to the BIMcollab platform: https://support.bimcollab.com/en/zoom…%E2%80%8B

FZK Viewer, a bit oldschool, not good with big models, but very accurate display of properties: https://www.iai.kit.edu/1302.php​

 

 

BlenderBIM: An open source solution for BIM projects?

BlenderBIM: An open source solution for BIM projects?

 

If you’ve never heard of Blender, it’s only a matter of time! In short, this is freely accessible graphics software, which offers, for example, 3D modeling, simulation, rendering, composition, motion tracking, video editing and animation pipeline functionalities. Created in 1998, it is currently being developed by the Blender Foundation.

Since 2019, the software has been increasingly recognized by companies in the graphics industry, such as Epic Games, Ubisoft or NVIDIA.

 

What’s new for us:

 

The BlenderBIM add-on has been around for some time: a specific add-on for Open BIM processes that rely on the BuildingSmart IFC format. It is built by volunteers from the IfcOpenShell project, still in development mode, and constantly evolving.

 

A new free BIM tool, on software recognized in the world of graphics, and capable of understanding the IFC format. What more ? This is how we focused our attention on the possibilities of this add-on. Is it possible to analyze and modify the data contained in an IFC for example? We summarize everything:

 

By default, in Blender, collections contain objects that have location, materials, etc. With BlenderBIM, we get several additional properties and functionalities: durability, price, description, globalID, assignment of IFC classes, assignment of attributes and sets of properties to elements, calculations of quantities from the geometry of objects, etc.

 

Taking into account the ability of this add-on to interpret the IFC format, we therefore asked ourselves the following question: can we think that Blender, technical and cutting-edge software in the field of graphics, can represent a help for stakeholders? of a construction project? Since BlenderBIM allows you to make modifications to an IFC mockup, it can be a solution in a BIM project, especially in the operation-maintenance phase.

In fact, during this phase, we start by using the model of the work executed “as built” in IFC format. In order to identify the functionalities this sotftware can offer to a project today, several tests were carried out on blender 2.92.0 (BlenderBIM addon blender28-bim-210404-py37-win, IFC2x3)

So here are examples of options we can obtain quite simply with the help of BlenderBIM:

  • The ability to view IFC models,
  • to be able to delete objects (and therefore by extension to divide IFC models by a new save),
  • To be able able to move objects, and change the values ​​of their properties
  • To be able to add new attributes to objects from Blender.

This is possible: but the IFC models we can export from Blender do not seem to keep the new properties, we consider that this option is still limited to a concrete deployment on a BIM project.

In short, from our point of view, IFC export remains difficult to master, and still seems to limit the possibilities of modifying the IFC format thanks to Blender.

To take a step back, it is also necessary to consider that this is a software whose technique is quite advanced and whose handling represents several years of practice.

However, we are counting on the meteoric progress of the BlenderBIM add-on to allow us to manipulate IFCs with more freedom in the future.

 

 

What is the difference between Formwork and Shuttering?

What is the difference between Formwork and Shuttering?

 

Introduction

 

Both formwork and shuttering are used to describe the procedure of making moulds in construction projects. In this process, the concrete gets poured & contained until it gets hardened. To simply put, shuttering formwork is used in concrete construction. While shuttering is a method of foaming moulds using the plywood, formwork creates moulds using a range of materials. Both shuttering and formwork accomplish more or less a similar task.

The primary difference between the two processes is the use of materials to accomplish this constructional job. In many cases, shuttering formwork is described as one form of formwork.

Let’s explore how different these processes are from one another.

 

Times When Shattering is More Significant than Formwork

 

Projects ranging in different sizes might require employing both the methods of formwork as well as shattering. The large-scale projects use a range of formwork types. But in almost all cases, shuttering is a popular option, given that the process is more straightforward and allows significant concrete amounts to be used at a single go.

Wall Form Shuttering

Making the right use of plywood to make shuttering becomes more inexpensive, especially when plywood is a recycling medium. Nonetheless, when it is about shuttering & formwork, not all plywood can serve the purpose. A special water-resistant plywood type is used for outdoors.

Wall Formwork

Falsework Support

 

Both shuttering and formwork will need the falsework support, that too in their various forms. Falsework, as a matter of fact, denotes stabilizers and poles, besides other units used to keep theme in place as the concrete dries.

Not all of these elements are permanent; some come as temporary ones too. So, this means that it can also be taken down right after the concrete sets. For permanent ones, the falsework gets removed as soon as the concrete sets in. This makes shuttering and formwork to remain in place permanently.

Basically, the difference between them is very little. But a definite example of formwork that does not use shuttering is in constructing concrete sidewalk. Rather than using timber for creating the mould, roadform (metal beams) can get used. It features a flat face right against which the concrete setting gets poured to create a clean edge. Connecting grooves and tongues are featured at either end of roadforms.

All you should Know about Surveying and Its Classifications

All you should Know about Surveying and Its Classification

 

Here is everything you need to know about surveying and its different classifications.

Surveying is a fundamental element of civil engineering since it is the initial stage in initiating a new civil engineering project.
A student must master the fundamentals of surveying in order to fully understand the procedures.
To begin learning surveying, one must first understand what surveying is and why it is important.

So first of all :

What is surveying ?

Surveying is simply the process of using direct or indirect measurements to determine the relative positions of various features on, above, or beneath the earth’s surface, and then putting them on a sheet of paper known as a plan or map.

Surveying skills are helpful in various of engineering processes. Any engineering project necessitates the use of surveying.
Below are some of the most important aspects of surveying.

You’re just about to know why surveying is that important , keep reading :

Why is it important ?

The first phase in surveying is to draw out a plan and a portion of the region that will be surveyed.
Based on the nature of the project, the best potential alignment, quantity of earthwork, and other relevant information can be computed using these prepared maps and sections.

Surveying measurements are used in the planning and design of all Civil Engineering projects, including railways, highways, tunneling, irrigation, dams, reservoirs, waterworks, sewage works, airfields, ports, enormous structures, and so on.

So, to conclude, any project of any size is built along the lines and points specified by surveying during its implementation as an initiation to its success and full achievement in the best possible ways.

 

Surveying most common classifications:

 

In order to get more in depth with surveying, you need to know that its most common classifications are:

  •  Plane surveying
  • Geodetic surveying.

Let’s start with the first one :

Plane surveying :

Plane surveying refers to surveying in which the earth’s mean surface is treated as a plane and the spheroidal shape is ignored.
Plane triangles include all triangles created by survey lines. All plumb lines are parallel and the level line is deemed straight.
We are only concerned with a small portion of the earth’s surface in everyday life, and the above assumptions appear reasonable in light of the fact that the length of an arc 12 kilometers long lying on the earth’s surface is only 1cm greater than the subtended chord, and that the difference between the sum of the angles in a plane triangle and the sum of those in a spherical triangle is only one degree.

And that was all you need to know about plane surveying for now.
Now, let’s jump into the second type of surveying which is « the geodetic surveying ».

Geodetic surveying :

 

Geodetic surveying the second method of surveying that takes into consideration the shape
of the earth.
The lines on the surface are all curved, and the triangles are all spherical.
As a result, spherical trigonometry is required to be able to master the different phases of
this kind of surveying.
All geodetic surveys entail labor at a bigger scale and with a high level of precision.
We can say that the goal of a geodetic survey is to identify the precise location on the earth’s surface of a set of widely separated sites that serve as control stations for less precise surveys.

To conclude, there are two types of surveying : the plane surveying and the geodetic one.
As a matter a fact, it’s up to the civil engineer to choose the best type based on each project he’s asked to accomplish.

The question now is :

Are there other ways to classify surveying ?

The answer is a massive YES and you’re about to discover some other ways of classifying surveying.

 

Classification based on nature of field:

There are three categories of surveying that are classified depending on the nature of the field:

  • Land surveying : which is divided into three categories: topographical survey, cadastral survey, and city survey.
    It is concerned with natural and man-made characteristics on land such as rivers, streams, lakes, wood, hills, highways, trains, canals, towns, water supply systems, buildings and properties, and so on.
  • Marine surveying : This classification of surveying is also known under the name of hydrographic surveying, is simply the species and elements related to the water for the purposes of navigation, water supply, harbor construction, and mean sea level determination.
    Measurement of stream discharge, topographic survey of coasts and banks, taking and locating soundings to establish water depth, and recording ocean tidal fluctuations are actually all part of the job we’re talking about.
  • Astronomical Surveying: This type of surveying allows a surveyor to determine the absolute location of any point on the earth’s surface, as well as the absolute location and direction of any line.
    This entails making observations of celestial bodies like the sun or any fixed star. (this one is quite interesting).

 

Classification based on instruments used :

Surveying can be split into six groups based on the different types of instruments employed :

  •  Surveying in a chain
  •  Surveying using a compass
  •  Surveying on a plane table
  •  Surveying using a theodolite
  •  Tacheometric surveying is a method of measuring the distance between two points.
  •  Surveying using photographs

Methods used for classification: Or in other words, classification based on the method used .
Surveying can be classified into the following categories based on the methodologies used:

 

  •  Surveying via triangulation
  • Surveying in a straight line

And … the last surveying classification , and my favorite one is :
Object-based classification:
There are four different forms of surveying based on the object:

  • Surveying of the Earth
  • Surveying of Mines
  • Surveying archaeology
  • Military reconnaissance

Different Types of Formwork Used in Concrete Construction

Different Types of Formwork Used in Concrete Construction

 

Formworks can be crafted from plywood, timber, steel, fabric and plastic as well. The formwork chosen for a particular construction process should be able to withstand the weight of the concrete. Therefore choosing the right type of formwork construction is essential to choose. Many types of the frame are available, which is mentioned below:

 

Timber Formwork

Timber formwork is the most widely used formwork. It has been commonly used in construction from the ancient period. It is quite economical and easy to access. Timber shuttering has the following advantages:

● It is lightweight
● Well composed
● It is easily accessible

Timber formwork is mainly used for small projects, and you can do the formwork construction with locally available timber. When compared with steel, it is quite lightweight.

Timber Formwork

Steel Formwork

 

Steel formwork is quite famous due to its durability, strength and capability of being used multiple times. It is advantageous for small projects, but they are also used for managing big projects. It provides a smooth texture when compared with the timber framework. It can be used in tanks, tunnels, columns and chimneys. Some of the advantages of steel formwork are as follows:

● It is durable and rigid
● Provides smooth finish
● It does not allow moisture to enter
● It can be used for multiple times

Steel Formwork

Aluminium Formwork

 

It is a fact that the density of aluminium is less when compared with the material steel, but it is lightweight. This formwork shares the same benefits as steel formwork. Working with aluminium formwork is indeed economical. It is used in completing big projects.

Aluminium Formwork

Plywood Formwork

 

Plywood formwork is a version of re-moulded timber. These are fixed with timber frames for manufacturing the panels of the desired size. Plywood timberwork is quite easy to manage, and it is flexible also. However, the life of plywood formwork is comparatively lower than other types of formwork.

Plywood Formwork

Fabric Formwork

 

With the development in the construction field, new technology is being used for planning and designing. The construction of complex-shaped fabric formwork has increased over the past few years. The main advantage of using fabric formwork is that it promotes flexibility and makes it possible for generating formwork of the required shape and size.

Fabric Formwork

Plastic Formwork

 

The best part of using plastic formworks is lightweight and can be used several times as well. It is best suited for concrete construction. This kind of formwork is widely becoming popular due to the multiple benefits that it provides. Some of the advantages of working with plastic formwork are given below.

● These material are lightweight, and therefore it needs less managing cost
● It is quite economical for big construction
● If it is being installed in the right way, no doubt it can be used multiple times.

Plastic Formwork

 

 

Different Uses of Box Culverts

Different Uses of Box Culverts

 

 

Introduction

A structure in constructions that allows water to flow under a road, railroad, or a similar obstruction is called a culvert.

These are generally made from a pipe or reinforced concrete and are embedded in the soil. Culverts come in different shapes. It can be round, elliptical, flat-bottomed, open-bottomed, pear-shaped, or box-like constructions.

Box culverts are those four-sided culverts used in making short-span bridges like over highways, waterways, etc. These are made of concrete and RCC (Reinforced Concrete) in particular. Box culverts come across as one of the most useful structures in modern construction. They serve various purposes like for intakes and outtakes, steam tunnels, corridor links, road crossings, service tunnels, and utility trenches.

Let’s understand the different uses of box culverts in detail below.

Uses of Box Culverts

 

Road and Highway Construction:

Box culverts are one of the most important features in road and highway construction. The box culverts let water flow under roads and highways without hampering the flow of traffic. Also, they serve as alternative animal crossings. Since these places need to endure traffic loads and extreme weather conditions, the culverts used here must be robust. Hence it is advised to build culvert out of concrete.

Highway Box Culvert

Use in Railroads :

Just like road or highway construction, box culverts are an essential element used in the construction and maintenance of railroads. They can be used here to replace small bridges or create crossings over creeks and any waterways.

Railway Box Culvert

 

Box Culverts in Utility Work:

Box Culverts are also required in utility work serving as utility tunnels that carry electricity, water, and sewer lines. In places where the climate is cold, and it is difficult to bury lines below the frost level, utility tunnels are imperative. Additionally, they are used to carry communication lines, such as telephone and cable television.

 

What makes Box Culverts Cost-Effective?

 

● Box culverts are a fast and economical method for tunnels under roadways.

● These can be tailored in large sizes to manage increased flow rates and capacities.

● Because of the rigidity and monolithic operation, separate foundations are not required which makes box culverts quite economical.

 

Suggested Read:

 

Reinforced Concrete Box Culvert Calculation Spreadsheet

Standard DWG Autocad Drawing For Box Cell Culvert

Pipe Culvert Wing Wall CAD template DWG

Culvert General Plan and Sections Details CAD Template DWG

Box Culvert Curved Concrete Layout CAD Template DWG

Box Culvert Concrete Reinforcement Details CAD Template DWG

Culvert Concrete Reinforcement Details CAD Template DWG

Box Culvert Design and Calculation Spreadsheet

What is a truss Bridge ? Types of Bridge Trusses

What is a truss Bridge ? Types of Bridge Trusses

 

Definition of a truss Bridge:

 

Truss is a structure of connected elements forming triangular units, and a bridge whose load-bearing superstructure is composed of a truss is a truss bridge.

From a mechanical point of view, truss structures are highly efficient in using the strengths of construction materials due to the fact that only axial forces are resisted in truss members.

Truss bridges are one of the oldest types of modern bridges. Trusses are generally assumed as pinned connection between adjacent truss members. Therefore, the truss members like chords, verticals, and diagonals act only in either tension or compression.

Axial forces in truss bridges under deadweight. (A) Pratt truss. (B) Warren truss.

 

Moreover, a truss is generally more rigid than a beam because a truss is composed of a variant of triangles and it has the ability to dissipate a load through the whole truss. The truss bridge is also called a beam bridge with braces.

For modern truss bridges, gusset plate connections are generally used, then bending moments and shear forces of members should be considered for evaluating the real performance of the truss bridges, which is achieved by the aid of finite element software.

For the design point of view, however, the pinned connection assumption is considered for security concerns and also for simplifying the structural design and analyses.

In addition, as the axial forces (but not bending moments and shear forces) are generally governs the stress conditions of the members, such assumption generally will not cause large errors between the real bridges and the design models.

According to this assumption, the truss members can be in tension, compression, or sometimes both in response to dynamic loads.

Owing to its simple design method and efficient use of materials, a truss bridge is economical to design and construct.

Short-span truss bridges are built as simply supported, while the large span truss bridges are generally built as continuous truss bridges or cantilever truss bridges.

 

 

Truss bridge examples

Types Of Trusses :

There are three common truss configurations that are often used in bridges, namely Warren truss, modified Warren truss, and Pratt truss.

All these truss configurations can be used as an underslung truss, a semithrough truss, or a through truss bridge.

Warren trusses have parallel chords and alternating diagonals. Warren trusses with verticals to reduce panel size are named as modified Warren truss.

Pratt trusses have diagonals sloping downward toward the center and parallel chords.

Truss types according to structural forms. (A) Warren truss. (B) Modified Warren
truss. (C) Pratt truss

What is Vibroflotation Ground Improvement Method?

What is Vibroflotation Ground Improvement Method?

 

Vibroflotation is a technique developed in Germany in the 1930s for in situ densification of thick layers of loose granular soil deposits. Vibroflotation was first used in the United States about 10 years later. The process involves the use of a vibroflot (called the vibrating unit).
The device is about 2 m in length. This vibrating unit has an eccentric weight inside it and can develop a centrifugal force.
The weight enables the unit to vibrate horizontally. Openings at the bottom and top of the unit are for water jets. The vibrating unit is attached to a follow-up pipe. The figure below shows the vibroflotation equipment necessary for compaction in the field.
The entire compaction process can be divided into four steps:
  • Step 1. The jet at the bottom of the vibroflot is turned on, and the vibroflot is lowered into the ground.
  • Step 2. The water jet creates a quick condition in the soil, which allows the vibrating unit to sink.
  • Step 3. Granular material is poured into the top of the hole. The water from the lower jet is transferred to the jet at the top of the vibrating unit. This water carries the granular material down the hole.
  • Step 4. The vibrating unit is gradually raised in about 0.3 m lifts and is held vibrating for about 30 seconds at a time. This process compacts the soil to the desired unit weight.

What is Footing ? Types Of Footings

What is Footing ? Types Of Footings

 

Introduction:

 

Foundation is the main part of any type of structure (Buildings, bridges, tunnels…). It distributes the weight of the structure over a large area of soil, avoid unequal settlement, increase structural stability and prevent lateral movement of structure.

There are different types of soil and for each individual one, soil bearing capacity is different. So, depending on the soil profile, size and load of the structure, engineers choose different types of foundation which can be shallow foundation or deep foundation.

Shallow foundation system consists of two main types: Footings and raft or mat foundation.

Footing is one of the most important parts of a structure which transfers loads of a structure to the underlying soil.

The selection of footing depends on the following factors:

  • The depth of the soil at which safe bearing strength exists.
  • The type and condition of soil.
  • The type of the superstructure.

Types Of Footings:

 

The different types of footings used for building construction are listed below:

  • Wall footing / Strip footing
  • Spread Footings
  • Isolated Footings
  • Stepped Footings
  • Combined Footings
  • Sloped Footings
  • Strapped Footings

Wall footing / Strip footings

 

Strip footings (known as strip foundations) are a shallow foundation type, usually boasting a foundation level that is no greater than 3m from the ground surface.

Strip foundations can be used for most subsoils, but are most suitable for soil which is of relatively good bearing capacity. They are particularly suited to light structural loadings such as those found in many low-rise or medium-rise domestic buildings – where mass concrete strip foundations can be used. In other situations, reinforced concrete may be required.

Very broadly, the size and position of strip foundations is typically related to the wall’s overall width. The depth a traditional strip foundation is generally equal to or greater than the overall wall width, and the foundation width is generally three times the width of the supported wall. This results in the load being transmitted at 45º from the wall base to the soil.

Wide strip foundations may be required where the soil is soft or of a low bearing capacity, so as to spread the load over a larger area. Wide strip foundations will typically require reinforcement.

Strip footing foundation

Spread Footings

 

The spread footing is utilized to support the column & walls and additionally to convey & disseminate the load coming to the structure to the soil below it.

With loads provided within the upward direction, this footing actually acts like an inverted cantilever, and this sort of footing is typically a rigid element & they’re orthogonal just in case of symmetric 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 soil is not exceeded.

 

Isolated Footings

 

Isolated footings (also known as Pad or Spread footings) are commonly used for shallow foundations in order to carry and spread concentrated loads, caused for example by columns or pillars.

Isolated footings can consist either of reinforced or non-reinforced material. For the non-reinforced footing however, the height of the footing has to be bigger in order to provide the necessary spreading of load.

Its thickness is constant and its shape can be circular, rectangular or square. It is economic and requires less excavation but its size is highly depended on the load and it is less resistant in lateral forces.

 

Stepped Footings

 

This type of footing includes the construction of a footing step by step until it reaches the desired width. This technique is mostly used in residential buildings but its utilization has been decayed over the last decades.

The stepped footing is a simple type of isolated footing which is provided over soil having less bearing capacity. Because of low soil capacity load need to be transferred on the larger area.

Stepped footings are also used to keep metal columns away from direct contact with soil to save them from corrosion effects. This type of footing carries the load of metal columns and transmit this load to the underground.

Stepped Footing Foundation

 

Combined Footings

 

Whenever two or more columns in a straight line are carried on a single spread footing, it is called a combined footing. Isolated footings for each column are generally the economical. Combined footings are provided only when it is absolutely necessary, as

  • When two columns are close together, causing overlap of adjacent isolated footings
  • Where soil bearing capacity is low, causing overlap of adjacent isolated footings
  • Proximity of building line or existing building or sewer, adjacent to a building column.

Combined Footing Foundation

Sloped Footings

 

The strapped footings having sloping top or side faces are known as sloped footings. This type of footing is useful in the construction of formwork.

Sloped or trapezoidal footings are designed and executed with utmost attention to maintain a top slope of 45 degrees from all sides. The amount of reinforcement and concrete used in the sloped footing construction is less than that of plain isolated footing. Therefore, it decreases the utilization of concrete and reinforcement.

Sloped Footing Foundation

Strapped Footings

 

A strap footing usually supports two columns, so it’s a special type of combined footing. If a property line exists at or near the edge of an exterior column, a normal isolated footing would be placed eccentrically under this column and it would tend to tilt.

This problem may be prevented by connecting this footing with the adjacent interior footing with a strap concrete beam. The use of a strap footing may be justifiable where the distance between columns is long and a regular combined footing is impractical due to the required large excavation.

Strap Footing Foundation

 

 

 

 

 

 

 

 

 

 

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