Some useful guidelines to work out the total loads on a column & footing

This article is about calculation of loads for column and footings design.

The following types of loads operate on a column :-

1. Self weight of the column x Number of floors
2. Self weight of beams per running meter
3. Load of walls per running meter
4. Total Load of slab (Dead load + Live load + Self weight)

The columns are also susceptible to bending moments which should be included in creating the final design. There are different types of advanced structural design software like ETABS or STAAD Pro which can be applied to design a good structure efficiently. The calculation for structural loading In professional practice is based on some fundamental assumptions.

For Columns: Self weight of Concrete is approximately 2400 kg per cubic meter that is identical to 240 kN. Self weight of Steel is approximately 8000 kg per cubic meter. Suppose a large column having size of 230 mm x 600 mm with 1% steel and 3 meters standard height, the self weight of column is approximately 1000 kg per floor, that is identical to 10 kN. So, here, the self weight of column is taken as among 10 to 15 kN per floor.

For Beams: The calculation is same as above. Suppose, each meter of beam contains dimensions of 230 mm x 450 mm exclusive of slab thickness. So, the self weight is approximately 2.5 kN per running meter.

For Walls: Density of bricks differs among 1500 to 2000 kg per cubic meter. For a 6″ thick wall with 3 meter height and 1 meter length, the load can be measured per running meter equivalent to 0.150 x 1 x 3 x 2000 = 900 kg which is equivalent to 9 kN/meter. The load per running meter can be measured for any brick type by following this method.

For autoclaved, aerated concrete blocks like Aerocon or Siporex, the weight per cubic meter should remain among 550 to 700 kg per cubic meter. If these blocks are utilized for construction, the wall loads per running meter remains as low as 4 kN/meter, that leads to cutback in construction cost.

For Slab: Suppose the thickness of the slab is 125 mm. Now, each square meter of slab contains a self weight of 0.125 x 1 x 2400 = 300 kg that is similar to 3 kN. Suppose, the finishing load is 1 kN per meter and superimposed live load is 2 kN per meter. So, the slab load should remain 6 to 7 kN per square meter.

Factor of Safety: Finally, once the calculation of the entire load on a column is completed, the factor of safety should also be taken into consideration. For IS 456:2000, the factor of safety is 1.5.

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How bubble deck technology is used in construction work

Bubble Deck belongs to the original combination method of connecting air, steel and concrete in two-way structural slab. Hollow plastic balls is embedded into the slab and reinforced with steel. The end result eliminates up to 35% of concrete that contains carrying effect at the time of restoring the two-way span strength. It can be used with most of the buildings particularly open floor design : educational, commercial, hospital and other organizational buildings.

Bubble Deck contains the following properties :-

Shear strength - 80% of solid deck slab
Deflection - Similar to solid slab
Weight - 40% below solid slab
Fire Resistance – 65% of solid slab

Bubble Deck slab belongs to a biaxial voided concrete slab in which high density polythene hollow sphere substitute the incompetent concrete in the middle of concrete slab.

Materials for building up the bubble deck

Steel: The steel reinforcement of MS or HYSD is applied.

Plastic Sphere: Void sphere formed with recycled high density polyethylene. It contains adequate strength & rigidity. It does not make any reaction.

Concrete: The concrete is formed with standard Portland cement with highest aggregate size of ¾ inch.

Bubble Deck Manufactured Components: It stands for a structural vacuumed smooth slab system that reduces dead weight of a floor slab by 33% facilitating longer span among column supports and forms an entire range of other cost and construction benefits.

The system acts as an alternative of all other supporting structure like beams or walls. The entire floor slab extents in two directions directly into pre-cast or in-situ reinforced concrete column.

Benefits of Bubble Deck:

Structural:
a. Less weight
b. No beams are necessary
c. Only few columns are essential
d. Make your choice for shape
e. Bigger Span

Construction
a. Fewer work on job site
b. Light weight, less equipment is necessary
c. Simple and does not require heavy jobsite work

Economy:
a. Huge savings for materials (slabs, beams, columns, foundation), up to 50%
b. Needs fewer carrying cost
c. Requirement of concrete is reduced up to 35%
d. Lower workforce, no carpentry, no beams and workers with less skill can be employed

Environmental:
a. Less material consumption (cement, aggregate, steel)
b. Less energy consumption (throughout production, transportation and lifting on construction site)



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The details about bills of quantities

With the measurement of quantities, the total price can be evaluated more elaborately & precisely to give cost feedback on the job, that at the same time can be applied numerically in cost planning of other works.

Bills of quantities offer the best possible ways to manage the cost of variations in the contract. It is extensively utilized for various post-tender work like material scheduling; construction planning; cost analysis; and cost planning.

The method of working out the quantities prior to tender is a crucial test regarding what is drawn and stated can in fact be built. By examining the drawings and reviewing the construction in detail is definitely helpful in recognizing the issues which may be omitted initially.

The direct costs & indirect costs should be taken into consideration for determining the entire cost of the project which are included in various segments of the BOQ.

As the cost is identified prior to commencement of the construction, a superior level of price certainty is maintained for the construction project.

Facilitates to provide a low tender price.
Accommodates with design changes and assists the cost management process.
Provides superior quality of tender document.

Minimize the risk of contractors managing the information in the BQ for their own purposes.
Bypass the risks with regard to both time and cost since the projects are calculated on the basis of the overall floor area.
The valuation of progress payment becomes simple with detail information as given in BQ.

May pass up the tendency of contractor to build up a conspire group and bid high for projects.

Video Source: Civil Engineer

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Characteristics of polymer-Modified Mortar

Mortar is considered as one of the vital components in masonry construction. It is normally formed by mixing water with portland cement, hydrated lime and sand. If the proportions of each of these ingredients are changed, strength and other characteristics may differ. Mortar with polymeric admixtures is applied extensively and inexpensively in definite situations.

Basics and function: Polymer-modified mortar is developed by interchanging a part of the conventional binders with polymers. Polymers are included with mortar to enhance the characteristics which may contribute to adhesion, toughness, flexural or tensile strength, and resistance to chemicals.

The purpose of the polymers is to make the capacity of work and adhesion of non hardened mortar better and often need fewer quantity of extra water as compared to conventional mortar. It leads to less pores and high capacity cements, consequently the immersion of water & and penetrability to salts are decreased.

Types of Polymers: Polymer-modified mortar is commercially obtainable with all constituents already provided in the mixture. Conversely, polymer additives separated into classes, are included with mortar mix. Redispersible polymer powders like ethylene vinyl acetate are normally included with dry mortar mix.

Water-soluble polymers like polyvinyl alcohol belong to powders but are added to wet mortar mix. Aqueous latex suspensions comprise of latex particles hanged up in water to coat hydrating cement particles. At the end, liquid polymers as epoxy resins or unsaturated polyesters are included throughout mixing to develop a network of cemented polymer hydrate and thus the strength of the mixture is raised significantly.

Application: Polymer-modified mortar is employed in a wide array of mortar and concrete repair and primary construction applications. Low water level and salt infiltrations transform polymer-modified mortar suitable for masonry prone to weathering and other exterior conditions. The main objective of polymer-modified thinset mortar is to bind tile to concrete and cement board substrates devoid of immersing the tiles earlier. Polymer-modified mortars are frequently applied for repairing purposes due to their low shrinkage and capacity to tie with even solid surfaces.

Supplementary Possible Admixtures: Besides, polymers, other types of materials can be included with mortars to attain required characteristics. Color pigments may be included with mortar to change the look of the mortar. If accelerators and retarders are included, these can decrease or raise the length of time necessary for the mortar to be cured, a vital characteristic to control in severely cold or warm, humid weather. Other mortar additives range from mineral additions, like silica fume, aggregates and inert fillers, plasticizing chemical admixtures and fibers to manage shrinkage efficiently.



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Some important points for civil site engineer

Civil engineer accomplishes several tasks at construction site. Given below, some points, tips and tricks essential for a civil engineer for doing rapid calculations and providing instant solutions to construction site problems.

Given below, some general points which civil site engineers should focus on to simplify the construction work whereas retaining the quality of construction.

Lapping should not be provided for the bars with diameters in excess of 36 mm.

Highest spacing for chair should be 1.00 m (or) 1 No per 1m2.
For dowels rod, lowest 12 mm diameter should be applied.

For Chairs, bars with minimum diameter of 12 mm should be utilized.
Longitudinal reinforcement should remain not below 0.8% and in excess of 6% of gross C/S.
Least bars for square column is 4 No’s and 6 No’s for circular column.
Main bars in the slabs should not be under 8 mm (HYSD) or 10 mm (Plain bars) and the distributors should not be under 8 mm and not in excess of 1/8 of slab thickness.

Least thickness of slab should be 125 mm.
Dimension tolerance for cubes should be + 2 mm.
Free fall of concrete is permissible maximum to 1.50m.
Lap slices should not be applied for bar greater than 36 mm.
Water absorption of bricks should not be in excess of 15 %.
PH value of the water should not be under 6.

Compressive strength of Bricks should be 3.5 N / mm2.
The binding wire in steel reinforcement should be required 8 kg per MT.
According to IS code for soil filling, 3 samples should be chosen for core cutting test for each 100m2.



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How to calculate mason, labor for brick masonry construction with help of thumb rule

In this construction video tutorial, you will learn how to compute the mason as well as labor toward a 1st class brick masonry construction with the help of thumb rule.

A thumb rule refers to a principle having extensive application that is not projected to be exactly perfect or authentic for each situation. This method can be easily applied for making approx calculation or recollecting some value, or for making some determination.

It should be noted that the quantity of required labor will be gradually increased from ground floor to first floor to second floor etc.

Thumb rule is a constant value that is taken from the earlier construction work i.e. how much volume is covered by the labors employed in earlier projects. All the volumes are summed up to find out the average volume.

In ground floor, first floor and second floor, the volume of total area is taken as 150 m3

Ground floor :-

Mason = Volume x thumb rule (for mason) = 150 x 0.71 = 107 numbers
Now, suppose the charge for one mason = 1100 rupees
So, the cost for mason will be 107 x 1100 = 117, 700 rupees

Labor = 150 x 1.18 (thumb rule for labor) = 177 numbers
Suppose, one labor charge 800 rupees
Therefore, cost of labor = 177 x 800 = 141,600 rupees

Similar process should be followed for 1st floor and 2nd floor. Here, the value of thumb rule will be increased as the steps are increase.

To learn the calculation for 1st and 2nd floor, watch the following construction video tutorial.



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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 www.concreteconstruction.net



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Benefits of floating column

Floating Column or Hanging Columns: The floating column belongs to a vertical member that is laid on a beam and it doesn’t deliver the load directly to the foundation. The floating column operates as a point load on the beam and this beam transmits the load to the columns situated under it.

The column may set out on the first or second or any other midmost floor as resting on a beam. Generally, columns are laid the foundation to deliver load from slabs and beams. But the floating column is laid on the beam.

It signifies that the beam providing support to the column performs as a foundation. That beam is known as a transfer beam. This is extensively applied in high storied buildings for both commercial and residential purpose. It facilitates to customize and rectify the plan of the top floors. The transfer beam that provides support to the floating column, reassigns the loads up to foundation. For this reason, it should have been designed with more reinforcement.

Floating Column in Buildings: In recent times, multi-storey buildings are developed for the purpose of residential, commercial, industrial etc., containing an open ground storey. To provide space for parking, the ground storey is reserved free devoid of any constructions, exclusive of the columns which move the building weight to the ground.

For a hotel or commercial building, usually, there are banquet halls, conference rooms, lobbies, show rooms or parking areas in lower floor, hence large alternate space is necessary for the transition of people or vehicles. The columns which are narrowly placed in the upper floors, should not be located in the lower floors. Hence, to get rid of this issue, floating column concept becomes vital.

In urban areas, multi storey buildings are developed supported with floating columns at the ground floor for the different objectives. These buildings with floating columns are treated as secured under gravity loads and therefore are designed only for those loads. But these buildings are not suitable for earthquake loads and hence, these buildings are treated as insecure in seismic prone areas.

When the floating columns are arranged in buildings in seismic prone areas, the whole earthquake of the system is allocated with the column or the shear walls devoid of assessing any contribution from the floating columns.

Floating Column & Earthquake: The floating columns are useful for various projects specifically over the ground floor, where transfer girders are used with the purpose of providing more open space in the Ground Floor.

In the earthquake prone zones, the transfer girders which are applied should be designed and detailed correctly. If no lateral loads exist, the design and detailing work will not be complicated.

Concept of floating column primarily includes disrupting flow of transfer of EQ force.

• Floating columns must be designed as a normal compression member.
• At the time of designing transfer beam, it is designed as beam bearing all that load of column as a single point load.
• It should be remembered that EQ force developed should be reduced along the shortest path. It means load is dispersed between two intermediate columns which provide support to that beam.

High shear capacity beams/deep beams are utilized to provide support to the floating column. In some areas, the floating columns are inevitable. So, it is essential to alter code provisions for deep beams.

Article Source: engineeringcivil.org



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Different Sorts Of Scaffolding

Definition of scaffolding

The impermanent framework containing platforms at various stages which permits masons to sit and continue their construction work at different height of building is termed as scaffolding. Scaffolding is required for masons to sit and put construction materials when the height of wall, column or any other structural members of a building exceeds 1.5m. It offers a temporary and a safe working platform for different types of work such as construction, maintenance, repair, access, inspection, and so forth.

Divisions of Scaffolding:

There are the following various divisions available:

Standards:

Standards indicate to the vertical member of the frame work that is used to support on the ground.

Ledgers:

Ledgers are the horizontal members which are running equivalent to the wall.

Braces:

Braces are diagonal members running or fixed on the standard to provide stiffness to the scaffolding.

Transoms:

While both the ends of put logs are sustained on ledgers, then they are called transoms.

Boarding:

Boarding is a platform which is horizontal to support workmen and elements which are supported on the put log.

Guard Rail:

Guard rails are supplied at the working level similar to a ledger.

Classification of Scaffolding

Scaffolding can be categorized into various kinds which are described below in a nutshell:

Single Scaffolding

For brick masonry works single scaffolding is widely used. This type of scaffolding contains a single framework of standards, putlogs, ledgers, etc. Standards are placed at a distance of about 1.2m from the wall at 2-2.5 m interval and are attached by ledgers at a vertical interval of 1.2 to 1.5m. One end of putlog is on the ledgers and the other one in the hole left in the wall at an intermission of 1.2 to 1.5m.

Double Scaffolding

Double scaffolding is usually used for stone masonry works. Stipulation of holes to withstand putlogs is tough enough, so double scaffolding is preferred containing two rows of standards segregated by ledgers. The first row of the scaffolding is located at 20-30 cm away from the wall and the next row is kept 1m away from the first row. Transoms are situated on the ledgers and the cross braces in the scaffolding assists to build them more powerful and durable.

Steel Scaffolding

Steel scaffolding is similar to mason scaffolding. It consists of steel tubes instead of wooden members. In such scaffolding, standards are placed at a space of 3m and are connected with the help of steel tube ledgers at a vertical interval of 1.8m.

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How To Lay Brick and Mix Cement Efficiently to Develop A Brick Wall

Get some useful construction tips on how to lay bricks and mix cement for a brickwall. To start the construction work from scratch, you require some good construction tools. Given below the detailed lists of construction tools :

• A brick trowel

• A spirit level

• A jointing bar

• A tape measure

• Line and pins

• A soft brush

Next you should learn how to mix cement.

Mixing cement is the most vital part of the construction processes. Ensure that you don't keep it too wet or too dry for utilization. The work must be based on a ratio basis. You can mix in the ratio of 4:1 (4 part sand to 1 part water) or 3:1 (3 part sand to 1 part water). But remember, once you set the ratio, it should be maintained until the work is completed otherwise the mortar will be drying in various shades./p>

If you can arrange a cement mixer then the mixing can be done smoothly. To start the mixing process, you will require the following items:

• Building Sand

• Cement

• Water

• Feb (Mortar additive)

Given below the stepwise processes for mixing mortar in a cement mixer:

• Load a bucket with water and include two sachets of feb. Use approximately a quarter of it into the mixer and turn it on.

• Keep the water and the feb to rotate for about 30 secs. Then include your first 3 shovels of sand (4 if the ratio is 4:1) Keep it to blend with the water and feb for some time.

• When the sand has developed a steady mixture (apply more water if it hasn't) and then include your shovel containing full of cement. Let it to be blended for some time and recur the step unless your mixer is packed. Include more water if required.‪

N.B.: Do not include water excessively. Initially, keep close eye on mixing process. It may appear too rigid but it frequently requires time to spin. If it still isn't appearing to be perfect then include little water at a time.

Mixing manually

• Ensure you contain an expansive wooden board for mixing. You should require it.

• Tip your 3 sand and 1 cement onto the board and blend simultaneously dry with the shovel.

• Make a hole in the middle of your sand so it appears to be a volcano.

• Add the water and feb from the bucket and blend it completely again.

• Recur these methods unless you obtain as much Mortar as per your requirement.

To go through the complete article, visit the following link dengarden.com

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