Slope deflection method - Structure Analysis for Civil engineering design

 Slope Deflection Method - To analysis of Structures

• Slope Deflection Method is useful to analyse indeterminate structures.
• Intdeterminate strutures like continuous beams and plane frames.
• The unknowns in slope deflection method are degree of freedom i.e. slope and deflection.
• Combinedly these slope and deflections are known as displacements. Thus slope-deflection method is a displacement method.
• It is classical method on whick moment distribution method, kani's method and stiffness matrix method are based.

Slope Deflection Method - force method or displacement method

•  It is Displacement method.

 Assumptions in Slope Deflection Method - Structure analysis

• Analysis of a beam and frame means determination of moment and shear force throughout the length of the member
• i.e. determination of BMD and SFD for the member.
• BMD and SFD for a member of structure can be drawn if we know the internal end moments of a member
• Thus, in slope deflection method we establish a relationship between the degree of freedom and the member end moments. This relationship is called slpe deflection relationship.
• Finally by using equillibriums equation we find the slpe deflection relationship to obtain the member moments
• To find out the slope deflection relationship method of superposition is used.
  
• Axial deformation are neglected.
• Shear Deformation are neglected.
• Clockwise moment is take as Positive (+)ve
• Clockwise rotation is take as Psitive (+)ve
• In slope deflection equation, deformation are considered to be caused by bending moments only.
  

Important points about Slope Deflection Method - 

• 1879 -1880 Heinrich Manderla invented similar to slope deflection method.
• 1882 - later Otto Mohr introduced improved methods of it called slpe deflection method.
• 1914 - Axel Bendixen gives great detail of slpe deflection method
• 1915 - George A mancy also gives details about slpe deflection
  

Step for Analysis in Slope Deflection Method

1. Computing of fixed end moment

    the formulae for fixed end actions for various load cases are given in many books and tables from where you can use.
   

2. Relate member and moments to joint displacement

    

   

   In slope deflection equation, deformation are considered to be caused by bending moments only.
   these are also known as solpe deflection equation 
   

3. Formulate equilibrium equations

    These are obtained by making algebraic sum of moments at each joint as zero.In case of frames with sway, additional equations are obtained consiering shear condition

4. Solve the equation

   This will give displacements (Primary unknowns) i.e. slope at joints and deflection.

5. Back-substitution

   In the expression for end moments formed in step 2 substitute value of known dispalcements as obtaind in step 4. this gives final end moments for each member form this,the support reactions can also be calculated.

6. Sketch shear force disarem and bending moment diagram .
   

Fixed Eng Momets Table with diagram

Fixed End Momets

 

 

Graphical Presentation of steps in the determination of slope deflection relationship

Consider all joints to be fixed and determine moments

Fixed support

Allow the one support to settle with respect to other support and find moments on support because of it

End moments caused by settlement of fixed support

 

Allow one end to roatate and find end moment because of it.

End momets caused by ration at hinge suport

 

Allow other end to rotate and find member moments because of it.

 

 

End moments caused by rotation at other supports

 

After adding all end moments for one supports we get

slope deflece equation

 

Frequently asked questions related to slope deflection methods based on ( FAQ'S )

Kani's methods is based on which principle?

• Kanis method is based on application of slope deflection method.
  
• Kanis method offers an iterative approach for applying slope deflection method, it is also known as rotation contribution method.
• In this method if an end of a meber is fixed the rotation at he end being zero, the rotation contribution at the end is also zero
• if an end of a member is hinged or pinned, it will be convenient to consider the end as fixed and to take the relative stiffness as 3/4th 

 what is slope deflection method on the basis of stiffness method or flexibility method?

• Slope deflection method is stiffness method in which unknown joint displacement are found out by applying the equilibriup condition at end
• In slope deflection eqution we use the principple of superposition by considering seperately the moments developed at each support due to each of the displacement ( slopes and displacements) and then loads, so displacement at joint are Independents.

What are the displacement methods other than slope deflection method to analyse indeterminate structures?

• Some displacement methods for anlysis of indeterminate structure.
  

1. Slope deflection method
2. Moment distribution method
3. Stiffness matrix method
4. Kani's method
   

When we use displacement method?

• Displacement method is suitable when Dk < Ds . Number of degree of kinetic indeterminacy is less than degree of static indeterminacy.
  

 

 

Read More →

Burj Khalifa - every civil engineers dream

 Burj Khalifa - Every Civil Engineers dream

Burj Khalifa - Civil Engineers Dream Project

Introduction:-

• Being the tallest building in the world and its beauty attracts anyone in the world. 
• The edifice is located in Dubai, United Arab Emirates. 
• With a total height of 829.8 m, the Burj Khalifa has been the tallest structure in the world since 2010. 
• The building was built within a period of 6 years. 
• The construction began on 6 January 2004 and ended in the year 2010. 
• The building was earlier known as Burj Dubai but was renamed in honor of the ruler of Abu Dhabi and the president of the UAE, Khalifa Bin Zayed Al Nahyan. 

Burj Khalifa Structure

                The world’s tallest building, Burj Khalifa took 6 years for its construction and was inaugurated on 4^th January 2010. The structure is 828m tall and the whole system is a reinforced concrete tower structure. This was the first attempt in world history to have such a large height for structures. This reason made the designers to employ one of the best and latest technology and innovative structural design. The structural features of Burj Khalifa is explained in the following section. 

 

• As the skyscraper has a floor plan of” Y” shape, this plan gives higher performance and provides a full view of the Persian Gulf. 
• Due to the integration of aerodynamic shaping and the plan, the structure can reduce the effect of wind forces. The central core has a higher resistance to torsion. 
• The total floor area of the building is 460000 sq meters. 
• The whole structure is designed as a reinforced concrete building with High-Performance Concrete up to level 156 and up to the top it is designed as a structural steel braced frame. 
• The C80 and C60 cube strength concrete is used with fly ash, portland cement, and the local aggregates.
• A Young’s Modulus of 43800N/mm2 is said to be granted by C80 concrete. The largest pumps in the world were used to pump concrete up to a height of 600 m at a single step

 

 

Burj Khalifa Project - height, storey, floors etc.

The structure is located in Dubai, United Arab Emirates. The structural features include:

• 160 + storey tower
• Podium structure adjacent
• Have a six story office adjacent
• A two story pool facility near

The tower comprises 2,80,000 m² area. This area is utilized for 700 residential apartments located from 45 to 108 floors. Remaining spaces is till the 160^th floor is occupied by the corporate officers. The total project cost is estimated to be US$20billion. The tower construction itself costs $4.2billion. The structural elements used and their amount is mentioned below:

1. Concrete Used = 250000 cubic meter
2. Curtain Walls = 83,600sq.m of glass and 27,900 sq.m of metal
3. Steel Rebars Used = 39,000 tones
4. Man-Hours = 22million man-hours

 

Burj Khalifa - shape of the tower

Adrian Smith is the man behind the structural and the architectural design of Burj Khalifa. The basic structure is a central hexagon core with three wings, which is clustered around it, as shown in figure-2. While moving up along the tower, one wing at each tier is set back. This makes decreasing cross section when moving up. The structure consists of 26 terraces.  

Burj Khalifa - Cross section

Cross Section plan of Burj Khalifa

 

Burj Khalifa - Structure system

The Burj Khalifa employs a ‘Y’ shaped floor plan. This plan provide higher performance and provides a full view of the Persian Gulf. The shape and the upward setbacks help the structure to reduce the wind forces that is acting on the structure. The shape was finally fixed based on the series of wind tunnel tests. The structural system employed for Burj Khalifa can be called as the Buttressed Core System. The whole system is constructed by using high performance concrete wall. Each wing buttresses the other through a hexagonal central core as shown in figure-2. The central core has a higher resistance towards the torsional resistance. The structure is more designed for wind force and related effects. There are corridor walls that extend from the central core to the end of the wing. At the end, these walls are thickened by means of hammer walls. These walls resist the wind shears and moments by acting like the web and the flanges of the beams. There are perimeter columns which are connected to the mechanical floors. The connection between the perimeter columns and the mechanical floors is provided by means of outrigger walls. This help to resists higher wind loads laterally. The outrigger depth is three storey heights. There is periodic encounter of outrigger system through the height of the tower.

 

Burj Khalifa - Concrete used in projects

The high-performance concrete used in Burj Khalifa guarantee low permeability and higher durability. The C80 and C60 cube strength concrete is used incorporating fly ash, Portland cement, and the local aggregates. A young’s modulus of 43800N/mm² is said to be granted by the C80 concrete. The largest concrete pumps in the world were used to pump concrete to height up to 600 m at a single stage. Two numbers of this type of pump was used. As the temperature of the location (Dubai) is very high, there were chance of cracks due to shrinkage. So, the concrete pouring process was carried out at night at a cooler temperature. Ice was added to the concrete mix to facilitate the desired temperature. To withstand the excessive pressure caused due to the building weight, special concrete mixes were employed. Every batch was tested before placing.  

Burj Khalifa - Foundation pile and raft

The superstructure of Burj Khalifa is supported over a large reinforced concrete raft. This raft is in turn supported by bored reinforced concrete piles. The raft has a thickness of 3.7m and was constructed in four separate pours. The grade of concrete raft is C50 which was self-consolidating concrete. The concrete volume used in the raft is 12,500 meter cube. The number of piles used were 194. The piles were 1.5m in diameter and have a length of 43m. Each pile has a capacity of 3000 tons. The concrete grade used in piles where C60 SCC concrete which were placed by tremie method. This utilized polymer slurry to carry out the process. To reduce the detrimental effects of chemicals, cathodic protection where provided under the raft.

 

Pile Raft Foundation in Burj Khalifa. Photos From the Construction Stage

Did you know about :- Burj Khalifa facts

Burj Khalifa World Records

At over 828 metres (2,716.5 feet) and more than 160 stories, Burj Khalifa holds the following records:

• Tallest building in the world
• Tallest free-standing structure in the world
• Highest number of stories in the world
• Highest occupied floor in the world
• Highest outdoor observation deck in the world
• Elevator with the longest travel distance in the world
• Tallest service elevator in the world

 

Tallest of the Supertall - Burj Khalifa

Not only is Burj Khalifa the world's tallest building but it has also broken two other impressive records: tallest structure, previously held by the KVLY-TV mast in Blanchard, North Dakota, and tallest free-standing structure, previously held by Toronto's CN Tower. The Chicago-based Council on Tall Buildings and Urban Habitat (CTBUH) has established 3 criteria to determine what makes a tall building tall. Burj Khalifa wins by far in all three categories.

• Height to architectural top

  • Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the architectural top of the building. This includes spires but does not include antennae, signage, flagpoles or other functional-technical equipment. This measurement is the most widely used and is used to define the Council on Tall Buildings and Urban Habitat rankings of the Tallest Buildings in the World.

• Highest occupied floor

  • Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest continually occupied floor within the building. Maintenance areas are not included.

• Height to tip

  • Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest point of the building, irrespective of material or function of the highest element. This includes antennae, flagpoles, signage and other functional-technical equipment.  

Amazing facts about Burj Khalifa 

• The skyscraper holds 900 apartments,3004 hotels, and 35 floor offices.
• The curtain wall of the whole building is equivalent to 17 football fields. It takes 3 months to 36 employees to clean the windows of the building from top to bottom
• It has 54 elevators which move with a speed of 40 miles per hour equivalent to 10 meters per second.  
• Burj Khalifa is three times taller than Eiffel Tower and two times taller than the Empire State Building.
• It holds the World’s highest outdoor observation deck at about 452 meters above the ground.  
• The skyscraper can be seen from a distance of 95 kilometers away from it.
• At the highest point of Burj Khalifa, visitors can enjoy the temperature different to 15 degrees lower.

• The skyscraper with 163 floors is constructed within a period of 6 years.No one would have thought that the World’s tallest skyscraper would be built within a short period of time.  
  

 

Burj Khalifa - Technology Used 

The tower is consisted of 163 floors and followed a very tight schedule of a 3-day cycle. The key construction Technologies are-

• Auto Climbing formwork System(ACS)

• Rebar prefabrication

• High-performance concrete provides high strength, high durability, and high pumping 

• Advance concrete pumping technology

• The  formwork system can be dismantled and assembled quickly with minimum labor work

• Column/Wall proceeding method.

 for More detail about burj khalifa visit following sites

source : 

https://civilengineeringbible.com/article.php?i=281

https://theconstructor.org/structures/structural-details-burj-khalifa-concrete-grade-foundations/20512/

 

PEOPLE ALSO READ IT

BRICKS - SIZE, SHAPE, CLASSIFICATION, DEFECTS, MANUFATURE, TYPES, STRENGTH, TESTS, ALL TOPICS CIVIL ENGINEERING ORIENTED

 

TIMBER- TIMBER, TYPE, CLASSIFICATION, DEFECTS, SHAKES, TESTS, DRY ROTS, WET ROTS-ETC, SEASONING, CONVERSION, ALL TOPICS CIVIL ENGINEERING ORIENTED 

 

MASONRY & TUNNEL - STONE MASONRY, RUBBLE MASONRY, QUAINS, KING CLOSER, QUEEN CLOSER, D.P.C., POINTING- ( STRUCK, TUCK, WEATHERED, BEADED, RECESSED ) , TUNNEL, OFF -SPUR TUNNEL, BASE TUNNEL, SLOPE TUNNEL, SPIRAL TUNNEL, TUNNEL JACKING, TUNNEL LINING, SHIELD TUNNELING, GROUTING, TUNNELING METHODS, TYPES OF TUNNEL SECTION,

 

Read More →

Top 10 Most Beautiful Civil Engineering Structures in the World

Top 10 Most Beautiful Civil Engineering Structures in the World

• 10. Lake Pontchartrain Causeway
• 9. Burj Khalifa
• 8. English Channel Tunnel
• 7. Golden Gate Bridge 
• 6. Hoover Dam
• 5. Itaipu Dam
• 4. Brooklyn Bridge 
• 3. The Colosseum
• 2. Great Wall of China
• 1. Great Pyramid of Giza 

10. Lake Pontchartrain Causeway

 

Lake Pontchartrain Causeway

The Lake Pontchartrain Causeway in Louisiana (U.S) spans the entirety of Lake Pontchartrain and is 23.83 miles (38.35km) in length. Despite it being opened decades ago in 1959, it is still the longest continuous stretch of bridge over water in the world. The causeway is supported by 9,500 pilings and is so stable that it has suffered a minute amount of damage from major hurricanes and storms when compared to any other causeway worldwide.

Read more - go to site 

9. Burj Khalifa

People also read it

Burj Khalifa

Burj Khalifa - Every engineers Dream - click here

Standing at 829.8 meters, the Burj Khalifa in Dubai is the tallest building in the world. The building’s incredibly tall design inspired the creation of the ‘buttressed core’, an engineering structural system with a hexagonal core which helps to support higher buildings than ever before. The building was named in honour of the ruler of Dubai and President of the United States Arab Emirates, and its design was inspired by the patterns and structures of Islamic architecture. The structure cost $1.5 billion to build. The building has been a major feature in popular culture; it can be seen in the 2011 film ‘Mission: Impossible – Ghost Protocol’ and 2016 film, ‘Independence Day: Resurgence’. Burj Khalifa has broken numerous other records, including building with most floors at 211 and it has received immensely positive acclaim from citizens, engineers and architects.

Burj Khalifa Project Details

The structure is located in Dubai, United Arab Emirates. The structural features include:

• 160 + story tower
• Podium structure adjacent
• Have a six story office adjacent
• A two story pool facility near

 Read more

8. English Channel Tunnel

The English Channel Tunnel links the shore of Kent in the UK with Pas-de-Calais in France. It has the longest undersea portion of any tunnel in the world, at 23.5 miles (37.9km). At its deepest point, it is 75 metres (250ft) below the sea bed and 115m (380ft) below sea level. It is designed to carry high-speed Eurostar passenger trains, international goods trains and a shuttle for road vehicles, making it the largest transport system of its kind in the entire world. When it opened in 1994, it was the most expensive project of all time, with the final cost of an astounding £9 billion. Despite other construction projects being more expensive in recent years, it still considered to be one of the highest-value engineering feats ever.

 Read more

7. Golden Gate Bridge

The Golden Gate Bridge is considered by many to be one of the most beautiful bridges in the world. This $27 million project is a mile-long suspension bridge that spans a strait, connecting the city of San Francisco to Marin County. It opened in 1937 and was the longest suspension bridge in the world for almost three decades. The bridge is one of the most recognised and influential symbols of the United States and has been declared a Wonder of the Modern World by the American Society of Civil Engineers.

 Read more

6. Hoover Dam

Constructed during the Great Depression, the Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado River. The construction of the Hoover Dam impounds Lake Mead, the largest reservoir in the United States. It was such a large project that several temporary towns were built during its construction to house the thousands of workers who made it. The dam is named after President Herbert Hoover, cost the equivalent of over $660 million to build and was completed in five years, two years ahead of its schedule.

 Read more

5. Itaipu Dam

On the Parana River, bordering Brazil and Paraguay lies the Itaipu Dam. This mega-dam produces more hydroelectric energy than any other dam in the world – measuring in at an immense 103,098,366-megawatt-hour (MWh). The energy produced by the dam is split evenly between Paraguay and Brazil, although it generates so much electricity that there is surplus energy for Paraguay which is transferred back to Brazil.

 Read more

4. Brooklyn Bridge

The Brooklyn Bridge is one of the oldest bridges in the United States and was the first steel-wire suspension bridge in the world. Completed in 1883, it connects the boroughs of Manhattan and Brooklyn by spanning the East River. The bridge was designed and completed by two generations of engineers, John August Roebling and his son Washington Roebling, who took charge of the project when his father became ill. It cost $15.5 million to build. Originally called the New York and Brooklyn Bridge, as well as the East River Bridge, its name officially changed to Brooklyn Bridge after 30 years of being called that by locals. Since its opening, it has become a historic icon of New York City and is one of the city’s most visited tourist attractions. It was designated a historic landmark in 1964.

 Read more

3. The Colosseum

The Colosseum is one of the most recognisable structures in the world and is the largest amphitheatre ever to be built. This structure is almost 2,000 years old and has a capacity of between 50,000 and 80,000 people, making it as large as many modern stadiums. This construction sits at the heart of Ancient Rome, Italy and was used for the entertainment of the Roman citizens. It has featured in countless examples of popular culture and is still studied and written about today.

 Read more

2. Great Wall of China

With a history of more than 2,000 years, the Great Wall of China is one of the greatest wonders of the world, and one of the most visited tourist attractions globally. Whilst it is known to Western cultures as the ‘Great Wall’, Chinese people refer to it as Chéng which means both ‘wall’ and ‘city’. The intrinsic connection between settlements and walls in China means that they share the same term, so the ‘Great Wall’ to us, is the ‘Long City’ and the ‘Long Wall’ to the people of China. The Great Wall stretches from Dandong in the east of the country to Lop Lake in the west. The entire wall with all its different branches, measures out at 13, 171 miles in length. It isn’t possible to know exactly how much the wall would have cost to build, but modern calculations say it would be somewhere between $13billion and $65 billion.

 

 Read more

1. Great Pyramid of Giza

The Great Pyramid of Giza is one of the Seven Wonders of the Ancient World, and despite being the oldest, it remains largely undamaged. It is the largest of the three pyramids in the Giza pyramid complex and was the tallest construction in the world for over 3,800 years. It is believed that the pyramid was built as a tomb for the fourth Dynasty Egyptian pharaoh, Khufu and was constructed over a twenty-year period. Many experts estimate that 5.5 million tonnes of limestone, 500,000 tonnes of mortar and 8,000 tonnes of imported granite were used to make it. Experts also estimate that it would cost around $5 billion to build a replica today.

 

 Read more


Across the history of mankind, we have used our intelligence to create large, impressive structures and buildings. There have been many great civil engineering projects that have become historic landmarks and icons, but we consider these to be amongst the greatest. They showcase our ability to design and construct our own unique vision.

Every engineer will have a different opinion on the most impressive creations. Honourable mentions include: the Millau Viaduct, which is the tallest cable-stayed road bridge in the world and the Shanghai Tower skyscraper in China, which is now the second-tallest building in the world. It is clear that the future of engineering is bright, and as technology advances, we will get to see even more incredible creations.

 

source - https://www.cobaltrecruitment.co.uk/blog/2017/03/top-10-most-impressive-civil-engineering-projects-of-all-time

Read More →

Basic Definitions and Simple Tests on Soil Mechanics

Introduction

This page discuss some of the basic definitions and simple tests used throughout the subject.

• The phase diagram is a simple, diagrammatic representation of a real soil.
• The phase diagram is also known as block diagram.
• A soil mass consists of solid particles, water and air, which are segregated and placed separately, known as three-phase system.
• A three-phase system becomes a two-phase system when the soil is absolutely dry (solids + air) or when the soil is fully saturated (solids + water).
• In phase diagram, volumes are represented on the left side, whereas weights are represented on the right side.

Volumetric Relationships

In total, there are fi ve volumetric relationships. These are as follows:

1. Void ratio (e):

• It is defi ned as the ratio of volume of voids to volume of solids.
• Range: e > 0
• e = Vv/Vs
• For some soils, it may have a value even greater than unity.
• The void ratio of coarse grained soils is, generally, smaller than that of a fi ne-grained soil.

2. Porosity (n):

• It is defined as the ratio of volume of voids to the total volume.
• n Vv/V
• Range: 0 < n < 1
• Also called ‘percentage voids’.
• Both porosity and void ratio are the measure of the degree of denseness (or looseness) of soil. Relationship between n and e:
• e = n /(n-1)
• n = e /(e+1)

3. Degree of saturation (Sr ):

• It is defined as the ratio of volume of water to the volume of voids, in soil.
• It is expressed as a percentage.
• Sr = Vw/Vv
• Range: 0 ≤ S ≤ 100%
• For dry soil, V w = 0 ⇒ S = 0
• For saturated soil, V w = V v ⇒ S = 100%

4. Percentage air voids (na ):

• It is defined as the ratio of volume of air to total volume, of soil.
• na=Va/V
• Range: 0 ≤ n a ≤ n

5. Air content (ac ):

• It is defined as the ratio of volume of air to the volume of voids, in soil.
• ac=Va/Vv
• Range: 0 ≤ a c ≤ 100%
• For dry soil, V a = V v ⇒ a c = 100%
• For saturated soil, V a = 0 ⇒ a c = 0
• Relationships between a c , n a , n and s:
• ac + S =1
• na= n*ac

Read More →

Soil Structure and Clay Mineralogy

Soil Structure

• Geometric arrangement of soil particles with respect to one another is known as soil structure.
• Depending upon the particle size and mode of formation, the following types are found.

Single Grained Structure

• Found in coarse grained soils, like gravel, sand.
• The major cause for formation is gravitational force. Here the surface forces are negligible.
• Under the influence of gravitational forces, the grains will assume a particle to particle contact referred to as single grained structure.

Single grained structure may be loose or dense as shown below.

• (a) Loosest state
• (b) Densest state

Honey-comb Structure

• It is possible for fine sands or silts.
• Both gravitational force and surface force are responsible.
• Such a structure can support loads, only under static conditions.
• Under vibrations and shocks, the structure collapses and large deformations take place.

Flocculated Structure

• This structure occurs in clays.
• Clay particles have a negative charge on surface and a positive charge on edges and flocculated structure occurs when there is an edge-to-face orientation.
• A flocculated structure is formed when there is a net attractive force between the particles.
• Soils with flocculent structure have a high void ratio and water content and, also have a low compressibility, a high permeability and high shear strength.

Dispersed Structure

• A dispersed develops in clays that have been reworked or remolded.
• Remoulding converts ‘edge-to-face’ orientation to ‘face- to-face’ orientation.
• Dispersed structure is formed when there is a net repulsive force between particles.
• Have low shear strength, high compressibility and low permeability.

Composite Structure

• A composite structure in the form of coarse grained skeleton or clay-matrix is formed when soil contains different types of soil particle

Clay Mineralogy

• Important clay minerals kaolinite, Illite, montmorillonite and halloysite, are present in clays.
• In coarse grained soils, like gravel, sand, rock minerals like quartz, feldspar, mica, etc., are present.

Kaolinite Mineral

• One molecule of kaolinite mineral is made of one silica sheet and one gibbsite sheet.
• Various such molecules are joined by hydrogen bonds.
• These show less change in volume due to changes in moisture content.
• Kaolinite is thus the least active of clay minerals.
• Example: China clay

Illite Mineral

• One molecule of Illite is made of two silica sheets and one gibbsite sheet, but in silica sheet, silicon atom is replaced by aluminum atom.
• Various such molecules are joined together by ionic bond (potassium ion).
• These shows medium swelling and shrinkage properties.
• Example: Alluvial soil.

Montmorillonite Mineral (Also Called ‘Smectite’)

• One molecule of montmorrilonite mineral is made of two silica sheets and one gibbsite sheet.
• Gibbsite sheet is sandwiched between silica sheets.
• Various such molecules are loosely bonded through water.
• These soils show high volume changes on moisture variation (i.e., large swelling and large shrinkage).
• Example: Black cotton soils, bentonite soil.

Diffuse Double Layer and Adsorbed Water

• Clay particles usually carry a negative charge on their surface.
• Because of net negative charge on the surface, the clay particles attract cations, such as potassium, calcium and sodium, from the moisture present in the soil to reach equilibrium.
• The layer extending from the clay particle surface to the limit of attraction is known as a diffuse double layer.
• The water held in the zone of the diffuse double layer is known as adsorbed water or oriented water.
• The plasticity characteristics of clay are due to the presence of adsorbed water.
• Clays using non-polar liquid, such as kerosene in place of water, does not show any plasticity characteristics.
• The thickness of adsorbed water layer is about 10–15 A°for colloids, but may be up to 200 A° for silts.

Read More →

Soil Mechanics - Study all topics

 Soil Mechanics Geo-technical

Engineering

Table of content

Chapter 1  Origin of Soils and Clay Mineralogy

• Introduction
• Soil formation and soil types
• Types of soil
• Commonly used soil designation
• Soil structure and clay mineralogy
• Soil structure
• Single Grained Structure
• Honey-comb Structure
• Flocculated Structure
• Dispersed Structure
• Composite Structure
• Clay Mineralogy
• Kaolinite Mineral other IMP link
• Illite Mineral
• Montmorillonite Mineral or Smectite
• Diffuse Double Layered Adsorbed Water

Chapter 2  Basic Definitions and Simple Tests

• Introduction
• Volumetric relationships
• Weight relationships
• Volume-weight relationships
• Specific gravity of solids (G)
• Mass specific gravity or apparent specific gravity (Gm )
• Important relationships
• Simple tests

Chapter 3  Index Properties and Soil Classification

• Introduction
• Index properties of soils
• Atterberg limits (or consistency limits)
• Soil classification

Chapter 4  Permeability

• Introduction
• Hydraulic head (h)
• Darcy’s law
• Seepage velocity (vs)
• Coefficient of absolute permeability (k )
• General expression for coefficient of permeability of soil
• Factors affecting permeability of soils
• Determination of coefficient of permeability

Chapter 5  Effective Stress and Seepage Pressure

• Introduction
• Definitions
• Importance of effective stress
• Effect of water table fluctuations on effective stress
• Capillary water
• Frost heave
• Frost boil
• Seepage pressure (P s )
• Quick Sand Condition
• Piping
• Prevention of piping failure
• Factor of safety against piping or quick sand

Chapter 6  Seepage Analysis, Stress Distribution and Compaction

• Introduction
• Seepage analysis
• Characteristic of flow net
• Uses of flow net
• Flow Net in an-isotropic soils
• Flow net in a non-homogeneous soil mass
• Flow net in a non-homogeneous soil
• Flow net in earth dams
• Stresses due to applied loads
• Compaction optimum wet and dry

Chapter 7  Consolidation

• Introduction
• Compressibility
• Consolidation
• Compaction
• Stages of consolidation
• Terzaghi’s spring analogy for primary consolidation
• Basic definitions
• Consolidation settlement (Sf )
• Consolidation of undisturbed specimen
• Over-consolidation ratio (OCR)
• Terzaghi’s theory of consolidation
• Differential equation of consolidation
• Degree of consolidation (U)
• Isochrones
• Determination of coefficient of consolidation
• Consolidation test
• Determination of void ratio at load increment
• Immediate settlement (Si )

Chapter 8  Shear Strength

• Introduction
• Definition
• Important points on mohr’s circle
• Strength theories for soils
• Coulomb envelopes for pure sand and for pure clay
• Types of shear tests based on drainage conditions
• Laboratory tests 
• Field tests
• Sensitivity of Soil
• Pore pressure parameters
• Liquefaction of sands

Chapter 9  Earth Pressure Theories

• Introduction
• Definition of lateral earth pressure
• Types of lateral earth pressure
• Rankine’s earth pressure theory
• Coulomb’s wedge theory
• Rehbann’s method

Chapter 10 Stability of Slopes

• Introduction
• Types of slopes
• Type of slope failure
• Different definitions of factor of safety (F s )
• Stability of an infinite slope of cohesion-less soils
• Stability analysis of an infinite slope of cohesive soils
• Finite slopes
• Swedish circle method or method of slices
• Location of most critical circle
• Effective stress analysis
• Bishop’s method
• Friction circle method
• Taylor’s method

Chapter 11 Bearing Capacity

• Introduction
• Types of foundation
• Definitions
• Criteria for determination of bearing capacity
• Factors affecting bearing capacity
• Compensated raft or floating raft
• Methods of determination of bearing capacity
• Types of shear failure
• Effect of water table on bearing capacity
• Meyerhaf’s bearing capacity theory
• Skempton’s analysis for cohesive soils
• Settlement analysis
• Plate load test

Chapter 12 Pile Foundation

• Introduction
• Necessity of pile foundations
• Classification of piles
• Pile driving
• Load carrying capacity of piles
• Negative skin friction
• Dynamic formulae
• Pile load test
• Group action of piles
• Efficiency of pile group ( h g )
• Group capacity of piles (Q g )
• Under reamed piles in clay

Chapter 13 Soil Exploration

• Introduction
• Objectives of soil exploration
• Methods of soil exploration
• Types of soil samples
• Corrections for standard penetration number
• Cone penetration tests
• Static cone penetration test
• Dynamic cone test
• In-situ tests using a pressure meter
• Geophysical methods

Other mixed up Topics on this site

Jump to Building Materials Subjects

this page is under development if anybody want to update welcome to join just send your comment

Read More →

Qualities of Good Timber - Building Material - Civil Engineering

Qualities of Good Timber

Following are the characteristics or qualities of a good timber:

1. Appearance quality of Good Timber: 

• A freshly cut surface of timber should exhibit hard and shining appearance.

2. Colour quality of Good Timber : 

• The colour of timber should preferably be dark. The light colour usually indicates timber with low strength.

3. Defects quality of Good Timber: 

• A good timber should be free from serious defects, e.g., dead knots, fl aws, shakes, etc.

4. Durability quality of Good Timber:

• A good timber should be durable. It should be capable of resisting the actions of fungi insects, chemicals, physical agencies and mechanical agencies.

5. Elasticity quality of Good Timber: 

• This is the property by which timber returns to its original shape when load causing its deformation is removed. This is a sought after property of timber when it is used for making bow, carriage shafts, sport goods, etc.

6. Fibres quality of Good Timber: 

• The timber should have straight fibres.

7. Fire resistance quality of Good Timber: 

• The timber is a bad conductor of heat. A dense wood off ers good resistance to the fire and it requires sufficient heat to cause a flame.

8. Hardness quality of Good Timber: 

• A good timber should be hard, i.e., it should off er resistance when penetrated by another body.

9. Mechanical wear quality of Good Timber: 

• A good timber should not deteriorate easily due to mechanical wear or abrasion.

10. Shape quality of Good Timber: 

• A good timber should be capable of retaining its shape during conversion or seasoning. It should not bow or warp or split.

11. Smell quality of Good Timber: 

• A good timber should have sweet smell. An unpleasant smell indicates a decayed timber.

12. Sound quality of Good Timber: 

• A good timber should give out a clear ringing sound when struck. A dull heavy sound, when struck, indicates a decayed timber. 
• The velocity of sound in wood varies between 2–17 times greater than that in air and hence, the wood may be considered high in sound transmission.

13. Strength quality of Good Timber: 

• A good timber should be strong for working as structural member, such as joist, beam, rafter, etc.

14. Structure quality of Good Timber: 

• It should be uniform. The fibres should be firmly added. 
• The medullary rays should be hard and compact.

15. Toughness quality of Good Timber: 

• A good timber should be tough, 
• i.e., it should be capable of offering resistance to the shocks caused due to vibrations.

16. Water permeability quality of Good Timber: 

• A good timber should have low water permeability which is measured by the quantity of water filtered through a unit surface area of specimen of wood.

17. Weathering effects quality of Good Timber: 

• A good timber should be able to reasonably withstand the weathering effects. 
• When timber is exposed to weather, its colour normally fades and slowly turns grey.

Read More →

Natural Seasoning and Artificial Seasoning of Timber

Differences between Natural Seasoning and Artificial Seasoning

Natural Seasoning 

• It is difficult to reduce the moisture content below 15–18%
• It is simple and economical.
• It is more liable to attack of insects and fungi.
• It requires more space for stacking.
• It is a slow process.
• It gives stronger timber.

Artificial Seasoning

• The moisture content can be reduced to any desired level.
• It gives weaker timber.
• It is a quick process.
• It requires less space for stacking.
• It is less liable to attack of fungi.
• It is expensive and highly technical.

Read More →

Building Materials - All content topic oriented

 Table of Contents

Chapter 1: Concrete and Its Constituents

• Cement
• Aggregates
• Admixtures
• Concrete

Chapter 2: Steel 

• Introduction
• Structural steel and metal
• Uses of steel
• Properties: Mild steel vs hard steel
• Defects in steel
• Steel manufacturing processes
• Mechanical treatment of steel
• Market form of steel and irons
• Different form of irons

Chapter 3: Bricks and Mortar 

• Bricks 
• Mortar and Limes
• Masonry and Tunnels

Chapter 4: Timber 

• Timber
• Structure of a tree
• Processing of timber
• Difference b/w natural and artificial seasoning
• Seasoning and preservation of timber
• Defects in timber
• Qualities of good timber
• MCQ for Timber - 1,2;
• Quick revision of timber

Chapter 5: Bitumen  

• Introduction

Chapter 6: Paint

• Introduction
• MCQ - 1 2 3 4 5 

Chapter 7: Stones and Glasses

• Stones
• Glasses

Read More →