adsense analytic

Monday, October 15, 2018

Benefits of post lintel structure

Post & Lintel is an easy form of construction that includes posts to bear horizontal beams or lintels found in timber-framed work or in columnar and trabeated architecture.

Stonehenge is a good example of post and lintel construction.

Post & Lintel System:

1. Post lintel belongs to a frame structure.
2. It is made of concrete materials by blending aggregates, gravel, sand and cement with water.
3. It is light weight or heavy weight structure.
4. The proportion of mixing comes as 1:2:4, 1:3:6 & 1:1.5:3 etc.
5. Currently, it can be utilized to form steel with regards to several codes and specifications like 80ksi, 60ksi & 40ksi.
6. 60ksi steel is mostly found.

Characteristics of post & lintels:

a. Post & lintels are illustrated as frame structure but columns and louvers.
b. Solid and void relationship is minor.
c. The invert beam is visible from above.
d. Existence of continuous beam.
e. The columns are arranged along the age of the building.

Benefits of post-lintel:

1. Post lintel structure in the outside facades enhances the appearance of the building.
2. Often, the enormous or inflexible masses are handled gently with the use of formwork of the post lintel to provide an elegant appearance.
3. Bigger space (column to column distance) of building can be designed in this system.
4. For the greater extent, the height of the lintel gets larger and for this a large distance appears as small due to the unavailability of clear height.

5. Sometimes, this issue produces visual disruption that can be resisted in flat slab.
6. The construction cost of this system is quite elevated for the laborious casting process of beam and slab and the application of R.C.C
7. The maintenance cost of this system is low as compared to other structural system because of it’s endurable characteristics.
8. Ingression of heat gets decreased in this system since the heat is transmitted from the slab to beam and then from beam to floor.
9. The control of openings allows the fewer amount of heat in the building.

10. Because of free flowing plan, the light and ventilation can easily be entered into the building.
11. This structural system contains less self-loads that can minimize the risk of earth quake.
12. The system can resist buckling or bending effect of the building from the powerful wind flow.
13. The system has good fire resistance strength for the construction material (R.C.C).
14. The system has fewer scope of failure as compared to other structural system.

Benefits of post lintel structure

Read more

Published By
Rajib Dey

Saturday, October 13, 2018

The stirrups commonly found in column design

The design of stirrups for column is created on the basis of different factors like changeable cross-sections, the number of longitudinal reinforcement bars and the load bearing strength. Stirrups in column construction are generally called as vertical ties or transverse reinforcement.

The following types of stirrups or ties are found in column construction:

1. Helical Reinforcement: The helical reinforcement is different from the lateral ties since the lateral ties contain spacing among individual ties. In helical reinforcement, the quantified value is pitch, rather than spacing.

The helical reinforcement offers more ductility and flexibility to the built up column with regard to lateral ties. They can effectively support the longitudinal reinforcement. With the insertion of helical reinforcement, the resistance capacity of the column structure against buckling become superior.

a) Ambient temperature of 27 °C (80°F) or greater; and
b) Evaporation rate that surpasses 1 kg/m2/h

The helical reinforcement is also applied as spiral reinforcement. Helical bars are suitable for seismic design. By the influence of seismic loads, the concrete affixed to the helical reinforcement is stripped off preliminary. It facilitates to give a warning sign concerning the structural condition of the column.

The helical reinforcement is a perfect example in respect of uniformly distributing loads as compared to the normal rings (lateral ties).

2. Lateral Ties: The lateral ties stand for transverse reinforcement to develop a separate ring with a fixed spacing among each link. Based on the column cross-section and the number of vertical or longitudinal reinforcement bars applied, the lateral stirrups vary from two-legged stirrups, four-legged stirrups or six-legged stirrups etc.

Given below, the detail information on various lateral tie configurations for several number of vertical reinforcement bars. The configurations are dependent on the ACI 315-99 recommendations.

1. Lateral Tie Configuration for 4- Bars: The tie is configured for 4 numbers of vertical column bars. It is a standard type of configuration applied for simple column design. This configuration is known as 2 legged stirrups column type.

2. Lateral Tie Configuration for 6- Bars: The first arrangement is observed when the spacing of vertical bars are under 150mm ( below 6”). If the spacing is in excess of 150mm, the second arrangement is observed where crossties are used.

3. Lateral Tie Configuration for 8- Bars: The first arrangement is done with the standard 8 number vertical reinforcement arrangement. Here the spacing is under 6”. If the spacing is in excess of 150mm, two crossties are utilized.

The third arrangement is known as bundled bars arrangement. Under this arrangement, two bars are combined at the corners. So, no cross ties are required. Highest 4 numbers of bars are combined.

4. Lateral Tie Configuration for 10- Bars: In this case, it is required to provide cross-ties apart from the square ties. It is also organized in bundled bars. Here bundle of 2 bars is arranged at four corners and two remaining bars are supported with the help of cross ties.

5. Lateral Ties for different column cross sections: The arrangement for 16 bars employ diamond ties. The process is very complicated to fabricate diamond ties perfectly and as a result it is ignored. The process is also complicated to arrange them properly. This tie arrangement is not suggested by ACI 315 because of the complications related to it. But, in some countries, standards utilize this arrangement for simple column design.

In A 16 bars column arrangement according to ACI 315 4 bundled bars can be arranged at each corner.

The stirrups commonly found in column design

Read more

Published By
Rajib Dey

Friday, October 12, 2018

Benefits of air entrained concrete

Air entrainment is the formation of tiny air bubbles in concrete. The concrete produced with this method is called air entrained concrete.

Air entrainment is provided in concrete with air entraining Portland cement or air entraining agents like admixture. The amount of air in such concrete generally remains among four to seven percent of the volume of concrete.

It is calculated with galvanometric method, volumetric method and pressure method. The air bubbles lessen internal pressure on the concrete by arranging chambers for water to spread when it freezes.

The objective of air entrainment is to enhance the strength of the hardened concrete, particularly in climates prone to freeze-thaw as well to raise workability of the concrete while in a plastic state.

Method - In the following ways, the air is entrained into the concrete:

1. By applying gas forming materials like aluminium powder, zinc powder and hydrogen peroxide.
2. By applying surface active agents that minimizes surface tension. They range from natural wood resins and their soaps, animal or vegetable fats or oils, alkali salts of sulfonated or sulphated organic compounds.
3. By applying cement dispersing agents.

Advantages - Given below, some of the advantages of the entrained concrete:

a. Workability of concrete is raised.
b. Impact of freezing and thawing is decreased significantly.
c. Bleeding, segregation and laitance in concrete are also minimized.
d. Entrained air makes the strength of concrete better against sulphate attack.
e. Minimizes the chance of shrinkage and crack development in the concrete surface.

Drawbacks - Given below, some of the drawbacks of air entrained concrete:

1. The strength of concrete is reduced.
2. The application of air entraining agent enhances the porosity of concrete and as a result the unit weight is decreased.
3. Air-entrainment in concrete should not be accomplished if the site control is not proper. It occurs as the air entrained in a concrete fluctuates with the alteration in sand grading, errors in proportioning and workability of the mix and temperatures.

Benefits of air entrained concrete

Read more

Published By
Rajib Dey

Thursday, October 11, 2018

Activities and liabilities of Quantity Surveyor and Quality Manager

Quantity Surveyor: The prime intention of the quantity surveyor is to measure the amount of materials required for building work as well as estimate the cost of the materials.

Usually, a quantity surveyor performs the following activities :-

• Commercial omission of site
• Formulation of financial reports, budgets and forecasts
• Supervision, training and development of some junior staff
• Job review of assistant staff
• Utilization of health and safety requirements

• Fulfillment of paperwork as desired by the CSIs/procedures
• Synchronization of enquiries for and evaluation of subcontractors (in conjunction with designers, buyers and other disciplines as required)
• Assuring that all subcontract documentation effectively describes the detailed requirements
• Insurance cover (quotations and implications)
• Calculation and disclosure of monthly valuation for certificate
• Preparation of claims, variation orders and day work
• Settlement of new rates for supplementary works
• Calculation of finished work and validation of compliance with specified requirements for subcontractor payment.

Quality Manager: The purpose of the quality managers is to make sure that the product or service that an organization renders is suitable for purpose, reliable and satisfies both external and internal requirements.

A quality manager undertakes the following responsibilities :

• Offers technical guidance on construction materials
• Provides instructions to line management on quality management matters helping agents or project managers with the formulation of their quality plans for individual projects
• Inspecting the execution of quality systems with regard to the CSIs/procedures by audit and surveillance, and instructing proper management of any corrective actions necessary and supervising their implementation
• Implementing or arranging audits on vendors, suppliers and subcontractors in association with purchasing managers
• Guiding all staff on their quality management responsibilities.

Activities and liabilities of Quantity Surveyor and Quality Manager

Read more

Published By
Rajib Dey

Wednesday, October 10, 2018

Importance of Self-leveling Overlays in concrete construction

Self-leveling overlays are set up rapidly. It is possible to place and finish more product each day, each worker as compared to any other cast-in-place decorative product.

Self-leveling overlays become effective when substrate conditions are less than standard: obsolete or worn concrete surfaces, unflat or unlevel floors, and concrete surfaces getting damaged with other floor treatments.

Self-leveling overlays are normally used in commercial building lobbies and corridors, retail spaces, residential floors, restaurants, and warehouse floors.

Self-leveling overlay products are susceptible to atmosphere conditions. Due to this, most applications are kept in controlled indoor environments. Specific jobsite conditions should be administrated with the purpose of attaining the following results :-

• Keeping uniform temperature
• Managing air movement to remove drafts
• Protecting from the direct sunlight to the work area
• Maintaining even relative humidity all through the jobsite

There should be a good bond among the subfloor and an overlay, so exact mechanical preparation of the accessible slab is vital. Bead-blasting equipment and diamond grinders are commonly applied tools but scarifiers are also utilized, particularly for thicker placements. The size of the required equipment is based on the size of a project concerning productivity.

Self-leveling overlay products are formed by mixing cement, fine aggregates, pozzolans, and admixtures comprising of superplasticizers, polymers, shrinkage compensators, and other components. Manufacturers' mixing instructions need applicators to mix a proper amount of water with each bag of material to attain the desired properties.

Initially, the material is placed on a sub slab, the average working time is only about 12 minutes, accompanied quick strength formation. Regular application thicknesses commence at about ¼ inch but can go beyond 2 inches devoid of shrinkage or cracking problems.

The toughened product is very solid and long-lasting and it contains compression strengths of roughly 6000 psi, and attains good flexural strengths.

When inherent colors are added to self-leveling overlays, the final product demonstrates strong color devoid of any efflorescence.

To get more details, go through the following link

Importance of Self-leveling Overlays in concrete construction

Published By
Rajib Dey

Tuesday, October 9, 2018

Consequences of Wrong Structural Design

This construction article sheds light on the causes of improper structural design.

Defects in Construction

Improper size of the Columns

If the size of the columns is 9”x9” and the building is likely to be built up to G+2 floors that is really unfavorable for the structure. It may cause structural failure and in due course structural collapse.

9”x9” size columns are suitable when it is required to build up a ground floor structure with M15 grade concrete. If it is necessary to build up another floor (G+1), the least size of the column should not be under 9”x12” with M15 grade concrete.

If it is required to utilize smaller columns (9”x9”); M20 grade concrete must have been utilized and the construction should not be started unless the client gives approval.

Incorrect alignment of the columns

The columns are not arranged in a straight line. When a wall is going to be developed connecting the columns, it becomes complicated to have a straight wall. It is so inaccurate. It is confusing how the beams will rest on the columns.

Incorrect wall construction

The construction process of the outside wall is also imperfect. The walls are not merged at a particular corner. If there is not a column construction in a corner, two beams approach together and rest on each other to provide strong support to the structure.

Consequences of Wrong Structural Design

Read more

Published By
Rajib Dey

Monday, October 8, 2018

The role of Site Engineer & Project Engineer in a construction project

Site engineers and project engineers frequently work in tandem on a job performing various things. Both play important role for major projects with equally significant liabilities.

Comparing Site Engineers to Project Engineers: Both the site engineers and project engineers take diverse liabilities for accomplishment for different types of construction projects.

Site engineers have sound technical skills which can be applied for specific engineering aspects of the project. Project engineers supervise the general operation of the project. They acquire the resource orders, deal with clients, and coordinate with designers and other engineers.

Given below, the basis differences among site engineers and project engineers :-

Liabilities of Site Engineers vs. Project Engineers

Site engineers perform according to a designer's plans, engineer's specifications and city codes to execute their jobs. Conversely, the project engineers perform very intimately with management and planners in an consultative manner to produce blueprints that fulfill the objectives of the clients as well as city and state codes.

Site Engineers: The site engineers may possess an office somewhere, but in several occasions they are active at the job site ensuring specific jobs are accomplished perfectly and with adherence to code.

These engineers examine that a building's wiring is completed properly, the plumbing will not leak, or the walls will not fall. They also have to rationalize modifications to orders, redrawing alternate plans and settling technical problems instantly and within the budget.

Given below, the liabilities of a site engineer:

• Performing as the top technical advisory on construction site
• Surveying, arranging and leveling the area for work
• Allowing planning data among managers, engineers and designers
• Tutoring trainees as well as junior engineers

Project Engineer: Project engineers have to accomplish all the paperwork, process the orders, and take care of the day-to-day operation of the site. They get in touch with all supervisors to overcome the issues before they spread.

These engineers set up timelines for supervisors to abide by. Project engineers have to supervise and coordinate with site engineers on the technical properties of the project. These professionals are accountable for status and budget reports together with personnel assignments.

Given below, the liabilities of a project:

• Evaluating of all plans and proposals prior to meet with management
• Scrutinizing bids for new projects
• Evaluating and examining of all drafts and blueprints
• Arrangement of cost estimates for materials, equipment and labor

The role of Site Engineer & Project Engineer in a construction project

Read more

Published By
Rajib Dey