Monday

DIFFERENT TYPES PLUMBING SYSTEMS USED IN BUILDING CONSTRUCTION


PLUMBING SYSTEM IN BUILDINGS


The plumbing system installed in the building has two main objectives to be served. They are:
  • 1.      Supply of water for the human use
  • 2.      To get rid of human waste

The plumbing system of a building will include the water distribution pipes, the fixture and the fixture traps, the waste, soil and the vent pipes, the building drain and building sewer, storm drainage system with their connected devices, connections and appurtenances within the building and outside, that is within the property line.

The figure-1 shows the basic plumbing system arrangement.

Saturday

HOW TO CALCULATE QUANTITY OF CEMENT REQUIRED FOR PLASTERING?

CEMENT MORTAR PLASTERING


Among different plastering methods like lime, cement, mud plastering, the cement plastering is considered as an ideal plastering method for external renderings. It is used and best recommended for damp conditions like
  • Ø  Bathrooms
  • Ø  Floors
  • Ø  Copings
  • Ø  Water Tanks
  • Ø  Areas where non-adsorbent surfaces are demanded




Thursday

NEED FOR WORKABILITY


Workability is a parameter that a mix designer is required to specify in the mix design process. A concrete which has high consistency and which is more mobile need not be of right workability for a particular job.




Tuesday

Requirements Of Fresh Concrete


Fresh Concrete or Plastic Concrete is a Freshly mixed material which can be moulded to any shape. The performance requirements of hardened concrete are more or less well-defined shape with respect to the shape, finish, strength, durability, shrinkage and the Creep. To achieve these objectives economically, the fresh concrete should satisfy a number of requirements from the mixing stage till it is transported, placed in the formwork and compacted.





Monday

STEP BY STEP INSPECTION ON BUILDING STRUCTURES



DIFFERENT LEVELS OF ASSESSMENT ON EXISTING STRUCTURE


The concrete structure will guarantee stability and durability throughout its lifetime only if it gains an appropriate safety margin to resist and fight against the expected service forces and the environmental factors. The concrete deterioration can be studied by undergoing step by step levels of inspection.
The different assessment levels are:

Saturday

Corrosion Damage In Reinforced Concrete


Damages Caused by Corrosion in Concrete Structure

The corrosion of steel can be termed as “creeping disaster” for a reinforced concrete structure. It begins with signs of weakness in the structure progresses with time causing the structure to exhibit unsightly cracks and finally causes the collapse of the structure.


Corrosion Damage In Reinforced Concrete
Fig.1. Concrete Pillar Damage - Exposure to Sea Water

Thursday

CIVIL ENGINEERING CODES USED IN EUROPE-BRITISH STANDARDS

EUROPE CONSTRUCTION CODES


The known BS standards - British Standard XXXX[-P]: YYYY where XXXX is the number of the standard, P is the number of the part of the standard (where the standard is split into multiple parts) and YYYY is the year in which the standard came into effect are the codes used in European countries. 



CORROSION OF CONCRETE- MECHANISM OF CORROSION IN CONCRETE



The corrosion of steel reinforcement is the depassivation of steel with the reduction in the alkalinity through carbonation.


Wednesday

VARIABILITY OF CONCRETE STRENGTH - FREQUENCY DENSITY V/S COMPRESSIVE STRENGTH DISTRIBUTION CURVES

The concrete compressive strength test result of cubes from a random sampling of a mix although exhibit variations, when they are plotted on a histogram are found to follow a bell-shaped curve, which is termed as the Normal or Gaussian Distribution Curve.




Monday

QUALITY CONTROL OF CONCRETE

The quality control is a corporate, dynamic program to assure that all the aspects of materials, equipment, and workmanship are well looked after.  The quality control should have conformity to the specification, no more, no less.
For the manufacturer of the concrete, the quality control process will involve material, personnel, equipment and workmanship in all stages of concreting.

INFORMATION TECHNOLOGY (IT ) IN CONSTRUCTION

INFORMATION TECHNOLOGY IN CONSTRUCTION





The involvement of many stakeholders and phases in the construction project have resulted in the fragmentation of the construction industry. The fragmentation of the industry has created documented problems which have resulted in the propagation of argumentative relationships between the parties to a project.  The studies have shown that this fragmentation is the main reason behind the low productivity observed in construction.

WEB BASED CONSTRUCTION PROJECT MANAGEMENT SYSTEM (WPMS)


Web -Based Project Management System (WPMS) is an electronic project management system that is employed and implemented through Extranet for the management of the construction industrial activities. The Extranet is a private network that uses the Internet protocols for the transmission of information.  This is an innovation as a result of the involvement of Information Technology in Construction Industry.




Sunday

Bond in R.C.C - Local Bond , Anchorage Bond and Development Length

WHAT IS BOND IN R.C.C?

When considering reinforced concrete design, “Bond” refers to the adhesion or the shear stress that is occurring between the concrete and the steel in a loaded member. This bond is the reason that makes the steel and concrete as a single unit without the cause of any slip. The assumption is simple beam theory that the plane sections remain plane after bending will be only satisfied if there is no kind of slip between the steel and the concrete.




Local Bond is defined as the magnitude of the bond stress at any point on the structural element between the reinforcement and the concrete. As shown in the figure below, the value will vary depending on the variation of bending moment along the section of the element.


Fig.1: Bond Stress – Local Bond; This stress is flexural in nature. The variation of tension with the change in the moment is shown.



Now, in order to support the full development of tension in the steel that is placed at the mid-section of the beam, it is required to be anchored on both the sides of the section. This will help to attain full tension capacity of the reinforced steel by the beam structure. Now the average stress that is acting along the anchorage length is called as the average anchorage bond. The average value is taken for design as the value of the local bond will vary along the length of the anchorage. The figure-2 shows the anchorage bond stress.
Fig.2: Anchorage Bond Stress




Development length in tension can be defined as the length or an extension that has to be provided on either side of the point of maximum tension in the steel in order to stop the chances of exceeding of average bond stress. When this has to be ensured in compression steel, we call it as Development length in Compression.
When mild steel bars were used, it was necessary to consider both the local bond and the development length in routine design checks. But when the use of high bond bars came, more importance was given to the development length of the local bond. This is because in high bond bars mechanics is more complex and undergo not only adhesion but also the mechanical locking due to the presence of projection on it. These are shown in figure-3. The development length is given by Ld . The calculation of development length varies with different codes.

Fig.3: Nature of Bond in smooth (a) and (b) deformed reinforcement bars




LOCAL OR FLEXURAL BOND


The local bond or the flexural bond is specified with respect to any point in any location of the R.C.C member. It is defined as the rate of change of the tension in steel at the given point in the R.C.C member. When the mild steel smooth reinforcement bars are considered, the local bond have great importance. The magnitude of the flexural bond at a point can be calculated by the following expression.

Considering a distance dx over the length of the R.C.C beam, let T be the increase in tension as from the figure-1. Then we have,

                              T = dM/jd                                             eq.1

If u is the local bond stress and ∑O is the perimeter of the steel that is provided, then corresponding tension acting at perimeter is u * (∑O)

The tension acting in distance dx is,

                                   u * (∑O) * dx                                          eq.2

Equating eq.1 and eq.2 we get,

u * (∑O) * dx        = dM/jd,


Therefore,

Hence,     



The mechanism of the bond between the reinforcement bars and the concrete will vary for the mild smooth bars and the deformed bars (Figure-3). Hence the above local bond stress is not valid for ribbed steel bars. The projection for the deformed bars is designed such a way that the local bond stresses are not taken place. Hence this is not calculated for ribbed bars.


AVERAGE OR ANCHORAGE BOND STRESS



The reinforcement anchorage is due to the:
  • Ø  Concrete and Steel adhesion
  • Ø  Concrete shear strength
  • Ø  Ribs interlocking with the concrete

This is prominent is the high bond bars. The codes recommend that the average bond stress which is developed along the full length of the bar surface which is placed in the concrete must be safe for ultimate loads also. The below is the value of bond stress for plain bars which are in tension. This is as per Indian Code IS: 456-2000. The Clause is 26.2.1.1- Table 10.2


Fig.4: A picture shot of Table.10.1 from IS:456-2000



DEVELOPMENT LENGTH


The length of the bar that is necessary in order to attain the full strength of the reinforcement bar is called as the development length Ld. The figure -5 shows the development length provision and its necessity.

Fig.5. The need for extending the bar by a distance of d beyond the theoretical cut-off point

The expression for Ld is derived by considering the yield strength in tension as 0.87fy



(Taking 0.87fy as steel design strength for compression)

When actual reinforcement that is provided is greater than the theoretical one, the actual stress is less than the full stress. Hence the development length required may be reduced by the following relationship.



This principle is followed in the design of footings and other short bending bars where the bond is considered very critical. The bond requirement can be satisfied by considering small sized bars or more steel. Always keep in mind that the Ld is calculated from the point of maximum stress. IS 456 gives simple rules for the Ld provision compared to other codes like BS and ACI.


END ANCHORAGE OF BARS


The steel reinforcement for both tension and compression will be extended beyond the theoretical length. This length extended will be equal to the effective depth of the structural element d or 12 times the diameter of the bar – whichever is greater is considered. This length is called as the anchorage length La . The need for an extension is explained in the figure-5. Any formation of diagonal cracks will result in the steel force that is corresponding to X and not Y. This value of La will be part of the Ld development length.


La = Greater of [Effective depth (d) or (12 * bar diameter)]

Rheology of Concrete- Factors Affecting Rheological Properties of Concrete

WHAT IS RHEOLOGY OF CONCRETE?


The Rheology may be defined as the science of the deformation and flow of materials and is concerned with the relationships between the stress, strain, rate of strain and Time.
The rheological principles and the techniques as applied to concrete include the deformation of hardened concrete, handling and placing of the freshly mixed concrete and the behavior of its ingredients.

The rheology of fresh concrete like workability include the parameters of stability, mobility, and compatibility, which are necessary to determine the suitability of any concrete mix. For the assessment of the rheological behavior of concrete, these parameters are redefined in terms of forces involved in the transmission of mechanical stresses on the concrete.
The fresh concrete is subjected to normal and shearing forces during its handling and placing.

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This is a center to bring up and collect all bits of knowledge and technologies flourished and flourishing to reach out for those who wish to acquire knowledge in a broader way. I am a structural engineer by profession and would like to share all information I have acquired all these years till date. This site also aims in researching new topics, works on your questionnaires and fill it up with good facts and information.

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