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Concrete and reinforced concrete are used as building materials in every country. In many, including the united states and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced concrete construction stems from the wide availability of reinforcing bars and the constituents of concrete, gravel, sand, and cement, the relatively simple skills required in concrete construction, and the economy of reinforced concrete compared to other forms of construction. Concrete and reinforced concrete are used in bridges, buildings of all sorts, underground structures, water tanks ,television towers, offshore oil exploration and production structures dams, and even in ships.



Title of the Book


Reinforced Concrete
Mechanics and Design

Author of Book


James G. Macgregor

University Professor Emeritus

Department of Civil Engineering

University of Alberta

Contents of the Book


Introduction
Design Process
Material
Flexure; basic concepts, Rectangular Beams
T beams and beams with compression reinforcement and special cases
Shear in beams
Torsion
Development, anchorage and splicing of reinforcement
Serviceability
Continuous beams and one way slabs
Columns : combined axial load and bending
Slender Columns
Two ways slabs
Equivalent Frame Method
Two way slabs : Elastic yield line, and strip method analysis
Footing
Shear Friction, Horizontal Shear Transfer, And Composite Concrete Beams
Discontinuity Regions, Corbles, Deep beams, And Joints
Design for Earth Quake Resistance

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Pre-tensioning and Post-tensioning is one of the widely used methods to enhance the load carrying capacity of the concrete structures like bridges, flyovers, dam spillways etc. After completing the pre-stressing the ducts or sheath pipes in post-tensioning is to be grouted with a suitable mixture with 24 hours after post-tensioning. 


Grouting of Post-tensioning Tendons 



The main objectives of grouting these ducts or sheath pipes in post-tensioned concrete members  are :-

(i) To prevent corrosion of the tendons,
(ii) To ensure efficient transfer of stress between the tendons and the concrete member, 
(iii) To improve the serviceability and strength characteristics of the concrete member. 

The grouting is a very sensitive and receptive process that needs careful supervision and inspection. Following are some of the points that must be complied while practicing the grouting of the post-tensioned concrete members :- 

1. In the grout mix, the quantity of sand or filler material should not be more than 30 percent of the mass of cement. 
2. The chloride content in the grout from all sources should not exceed 0.1 percent by mass of the cement. 
3. Material of grout should be batched by mass. 
4. Optimum water / cement ratio is 0.40 without admixture and with admixture can go upto 0.35 
5. The grout should be kept in slow continuous agitation until it is ready to be pumped into the tendon ducts. 
6. Grout should be mixed for minimum of 1 to 2 minutes but not more than 4 minutes. 
7. All the piping, pumping and mixing equipment should be thoroughly washed with clean water after each series of operations. 
8. Ducts should be completely filled with grout after injection. 
9. Ducts should be grouted at a continuous and steady rate of 6 m / min to 12 m / min for horizontal ducts and 2 to 3 m / min for vertical ducts. 
10. Grouting pressure should not exceed 2 N / mm2 
11. Grouting should continue until the fluidity or density of grout flowing from free ends and vent openings is same as that of original grout. 
12. After closing all the vents the pressure of 0.5 N / mm2 should be kept for 5 minutes. 
13. Vertical and inclined ducts should be grouted from the lowest points. 
14. Maximum length grouted in one operation being 50 m. 
15. Effectiveness of grouting should be checked by non-destructive testing such as gamma radiography. 



Mauvoisin Dam is a concrete variable radius arch dam across the Val de Bagnes on the Dranse de Bagnes stream, in the canton of Valais, Switzerland. Initial construction on the dam commenced in 1951 and was completed in 1957, with the reservoir filling by 1958. In 1991, the dam was raised to increase the capacity of the reservoir for winter storage.The dam's primary purpose is hydroelectric power generation.







The eighth highest dam in the world, Mauvoisin stands 250 metres (820 ft) high and 520 metres (1,710 ft) long, with a structural volume of 2,030,000 cubic metres (2,660,000 cu yd)


A Washington man’s cement home is still standing after surviving a raging wildfire that passed his home and scorched acres of surrounding land.

John Belles said he was prepared for the inevitability of a wildfire when he built his thin-shelled, concrete dome in 1999 surrounded by dry fields in Okanogan County.






ABC Latest News | Latest News Videos

Geopolymer concrete, or green concrete, is part of a movement to create construction materials that have a reduced impact on the environment. It is made from a combination of an inorganic polymer and 25 to 100 percent industrial waste. Here is a list of 4 benefits to using green concrete for your next project.


1. Lasts Longer: Green concrete gains strength faster and has a lower rate of shrinkage than concrete made only from Portland Cement. Structures built using green concrete have a better chance of surviving a fire (it can withstand temperatures of up to 2400 degrees on the Fahrenheit scale). It also has a greater resistance to corrosion which is important with the effect pollution has had on the environment (acid rain greatly reduces the longevity of traditional building materials). All of those factors add up to a building that will last much longer than one made with ordinary concrete. Similar concrete mixtures have been found in ancient Roman structures and this material was also used in the Ukraine in the 1950s and 1960s. Over 40 years later those Ukrainian buildings are still standing. If buildings aren't constantly having to be rebuilt, fewer construction materials are needed and the impact to the environment during the process of making those materials is reduced.
2. Uses Industrial Waste: Instead of a 100 percent Portland cement mixture, green concrete uses anywhere from 25 to 100 percent fly ash. Fly ash is a byproduct of coal combustion and is gathered from the chimneys of industrial plants (such as power plants) that use coal as a power source. There are copious amounts of this industrial waste product. Hundreds of thousands of acres of land are used to dispose of fly ash. A large increase in the use of green concrete in construction will provide a way to use up fly ash and hopefully free many acres of land.
3. Reduces Energy Consumption: If you use less Portland cement and more fly ash when mixing concrete, then you will use less energy. The materials that are used in Portland cement require huge amounts of coal or natural gas to heat it up to the appropriate temperature to turn them into Portland cement. Fly ash already exists as a byproduct of another industrial process so you are not expending much more energy to use it to create green concrete.
Another way that green concrete reduces energy consumption is that a building constructed from it is more resistant to temperature changes. An architect can use this and design a green concrete building to use energy for heating and cooling more efficiently.

4. Reduces CO2 Emissions: In order to make Portland cement–one of the main ingredients in ordinary cement–pulverized limestone, clay, and sand are heated to 1450 degrees C using natural gas or coal as a fuel. This process is responsible for 5 to 8 percent of all carbon dioxide (CO2) emissions worldwide. The manufacturing of green concrete releases has up to 80 percent fewer CO2 emissions. As a part of a global effort to reduce emissions, switching over completely to using green concrete for construction will help considerably.

Brick masonry is always a difficult task to perform regarding quality. This tool will let you do this in short time and with accuracy.




Dredging is a process that involves the aquatic excavation of water beds to remove sediments, pollutants, shellfish and other materials. The methods and machinery used in dredging vary widely. Most dredging is done by ships that tow a dredge along the water bed. Self standing dredges and dredge pumping stations are used for routine tasks. A dredge, which is the catch all term for the different types of machinery that perform dredging, can cut away sediment, scoop materials out like a back hoe or suction them through a large pipe to be deposited into a ship, barge or other containment system.



Dredging serves four general purposes:

 

1) Dredging is preformed to create or deepen waterways to allow large ships to pass. Throughout time, waterways become filled with silt and sediment which require fairly general maintenance in order to be efficient. With ever expanding markets, there is also a demand for the creation of new waterways.
2) Dredging is used to catch seafood. This type of dredging involves dragging a metal mesh net along the bottom of the ocean floor or other large body of water to catch animals such as crabs, fish and squid.
3) Dredging is performed in the attempt to remove pollutants and invasive species of plants from a particular body of water, although this practice is controversial. Removing pollutants this way often causes other environmental problems such as the destruction of habitats of important plant and animal species.

Mistakes and blunders are always every where when you want to work or struggle is there. Civil Engineers also make mistakes but some of them can be disastrous and dangerous you can see in this video how some mistakes takes the life of hundreds in just few seconds.



Here is the video

Construction Fail Compilation
Construction Fail Compilation
Posted by Civil Engineering Discoveries on Sunday, August 2, 2015

The Structural loads are supported on soil through foundations. These loads produce stresses and resulting strains or deformations in the soil below the foundation. The deformation in the vertical direction is usually termed as settlement, which occurs due to the vertical stresses.

Stresses in a Soil Mass

The stresses which produce excessive deformations are termed as failure stresses

Geostatic Stress or Over Burden Pressure 

At any point within soil mass, stresses are also developed due to the soil layer above that point, known as geostatic stress or over burden pressure. The magnitude of geostatic stress at a point is affected by the groundwater table fluctuation above that point. 

The intensity of stress developed is not uniform but vary from point to point. For the design of structure such as retaining walls, sheet piles for braced excavations and water front structures and some types of pile foundations, stress acting in the horizontal direction are more important. 



The knowledge of stress distribution along a soil cross-section is important to analyze the problem such as :- 

  • Settlement of foundations
  • Stability (bearing Capacity) of foundations
  • Stability of Slopes
  • Stability of Retaining Structures

Types of Stresses

A soil mass is a skeleton of solid particles enclosing voids which contain water (saturated soil) or air (dry soil) or both (partially Saturated Soil), When stresses are applied, the volume of soil skeleton reduces due to rearrangement of soild particles into new positions, mainly by rolling and sliding. 

The reduction in volume brings the particles closer resulting in an increase in the forces acting between the particles at the iner-particle contacts. The forces acting between the particles remain unchanged if the arrangement of  the solid particles does not occur. 

In a fully saturated soil, a reduction in volume is not possible, unless some of the water escapes from the voids. Water within the voids can also withstand stresses by an increase in pressure when the soil is fully saturated. 

In a saturated soil mass, the following three types of stresses are generally considered while dealing with soil engineering problems :-

Total Stress

The stress developed at any point in a soil mass due to the total weight of the soil lying above that point is known as the total stress. It is the sum of the products of unit weight multiplied by thickness for all the layers above the level considered. If there is water above the ground surface it will also add to the total stress (unit weight of water x depth of water). 

For the soil mass shown the total stress at Section X-X is written as follows :- 


The expression for the total stress at section XX for the soil layers shown is as follow :- 

Neutral Stress (Pore Water Pressure) 

It is the pressure of water filling the voids between the solid particles. It is equal to the hydrostatic pressure (unit weight of water multiplied by the depth of water above the point where neutral stress is required). 

It is termed as neutral stress since it acts equally in all directions. 

It is important to keep in mind that the neutral stress reduces the inter-particle stress and this condition has an adverse effect on the strength of the soil.

The neutral stress or hydrostatic pressure at section XX is given by



Effective Stress

It is the portion of the total stress which is carried by the solid particles at their points of contact. In other words, it is the sum of the vertical components of the forces developed at the points of contact between the soil particles divided the cross-sectional area of the soil mass. 

It is the effective stress due to which frictional resistance against particle movement such as rolling, slipping, sliding etc. develops. 

If the effective stress is zero, the soil mass is in a critical (unstable) condition. 
Effective stress is expressed as follow :- 
The effective stress at section XX is therefore calculated as given below :-



γ_sub or γ_'  is the submerged or buoyant unit weight of the soil.

If the water table rises to the ground surface the effective stress will be equal to “γ_sub (Z+D) and if the water table lowers down to XX, then the effective stress will be equal to “γ_b (Z+D)". Hence it can be said that the lowering of water table causes an increase in the effective stress, the effect of buoyancy is reduced.

Effective stress is independent of the depth of water above the ground surface. 







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