New technology in earthquake engineering to resist collapsing of the structures

It is the big challenge for the structural engineers to develop earthquake resistance structures.

An Earthquake resistant structure should have the capacity to resist abrupt ground shaking to reduce the damages to the structure.

Though the reinforced Concrete contains sound earthquake resistance capacity of buildings but owing to the substandard mix design of concrete and improper curing the reinforced concrete lost it’s desired compressive strength and it leads to collapsing of structure during an earthquakes.

Recently, a new innovation is launched in earthquake engineering where the curtain of cables is affixed to ground to significantly enhance the earthquake resistance strength of the building.

In these technology threads are used which are created with thermoplastic carbon fibre composite. These threads are fastened and knotted to produce a strong flexible rod which is 90% lighter as compared to reinforcement bars and contain the equivalent strength.

To resist earthquake successfully, these composite rods are fastened & secured from the roof to the ground and set up around the building. Rods are also set up inside the building to make the interior walls stronger.

These Composite threads are formed with textiles so that the rods can expand and pull the structure back in opposite direction to withstand shaking of the structure.

When an earthquake occurs, in case the building is pushed towards left side, the threads or rods located on right side pulls it back to retain the building in exact position and significantly reduces the structural damage and human death.

For online demonstration of this new technology, go through the following video tutorial.

Video Source: TomoNews US

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Published By
Rajib Dey
www.constructioncost.co
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Various types of notations used in the construction of concrete culvert design

The following notations are used in the drawing of concrete culvert design.

With notation, it is possible to make clear communication among various project stakeholders. Notation helps in avoiding mistakes in any construction project.

A’ = The valid contact area of a footing, measuring unit is in square metres
A = A detailing dimension for culverts that contains skewed ends, measuring unit is in mm
B = Depth of the bottom slab of a box culvert, measuring unit is in mm
B = Gapping among adjoining bars with reference to detailing tables, measuring unit is in mm
C = A coefficient that is applied in finding out the quantities of reinforcing bar.
CANBAS = Canadian Bridge Analysis System
c’ = the valid cohesion among the base of the footing and the soil at the ULS, with reference to CHBDC. kPa
CHBDC = Canadian Highway Bridge Design Code, 2000 Edition
CGSB = Canadian General Standards Board
F = Width of footing for open footing culverts, measuring unit is in mm
F1 = A reinforcing bar spacing factor, measuring unit is in mm-1
HULS = maximum factored horizontal reaction at the level of the base of the footing at the ULS, kN
Lc = Culvert length that is calculated the longitudinal axis, measuring unit is in m
OCPA = Ontario Concrete Pipe Association
OMBAS = Ontario Modular Bridge Analysis System
OPSS = Ontario Provincial Standard Specifications
S = Culvert distance that is calculated perpendicular to the longitudinal axis of the culvert, measuring unit is in mm
SLS = Serviceability limit states, in accordance with CHBDC
T = Depth of top slab of culvert, mm tan φ’ effective friction coefficient for concrete cast against soil.
ULS = Ultimate limit states, with reference to CHBDC
V = Unfactored vertical reaction because of the dead load of cast-in-place concrete and soil fill, at the level of the base of the footing, kN
VSLS = Maximum vertical reaction at the level of the base of the footing at SLS, kN
VULS = Maximum factored vertical reaction at the level of the base of the footing at ULS, kN
W = Depth of wall of culvert, measuring unit is in mm
Γ = The extreme angle among the normal to the longitudinal axis and the end of the same culvert, degrees
φ’ = The valid angle of internal friction, with reference to CHBDC, measuring unit is in degrees
θ = Skew angle of culvert, degrees



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Published By
Rajib Dey
www.constructioncost.co
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Get some useful tips to conduct your leveling survey at home

While going to layout something for road, bridge, dam or pipe line, land surveying plays an important role. Surveying is done to find out the legal boundaries among the parcels of property, the position of current infrastructure, the topography as well as slopes of the land.

Traditional measurement tools like a tape measure and protractor are not suitable for accomplishing large civil structures and public works projects.

In this construction video tutorial, Mr. Grady shows some useful tips which will help you to conduct your own topographic or leveling survey at home with fairly elementary and cost-effective tools. You don’t require any knowledge with sines, cosines, or tangents.

To learn the complete process, go through the following video tutorial.

Video Source: Practical Engineering

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Published By
Rajib Dey
www.constructioncost.co
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Basic differences between Development length and Lap Length

Development length is treated as specific minimum length of the bar that is needed on either side of a point of maximum steel stress, so as to transmit the bar force to encompassing concrete through bond devoid of slip, so that the bar is not pulled out under tension. Hooks, bends, mechanical anchorages are applied to supplement.

Lap length: When the steel is arranged in RC structure, if the necessary length of a bar is not suitably obtainable to produce a design length, then lapping is highly recommended.

Lap length stands for the least length that should have been arranged if two bars are attached together in order that forces are transmitted securely.

As for instance, while going to construct a tall column with height 100 feet. But, it is not possible to find a 100 ft long bar practically for caging. So, it is useful to slice the bars in each second story. Now, the tension forces are transmitted from one bar to the other at the location of discontinuity of bar.

Therefore, it is required to arrange the second bar nearer to the first bar that is suspended and overlapping should be provided. The amount of overlapping among two bars is defined as lap length.

LAP LENGTH IN TENSION.

1. For flexural tension – Ld or 30d either is larger.
2. For direct tension – 2Ld or 30d either is larger.

The straight length of lapping should not remain under 15d or 20 cm.

LAP LENGTH IN COMPRESSION: The lap length in compression should be similar to the development length in compression already worked out but not under 24d.

FOR DIFFERENT DIAMETER BARS: In case of bars with various diameter should have been cut off, the lap length is computed based on shorter diameter bar.

Article Source: quora.com

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Published By
Rajib Dey
www.constructioncost.co
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Different types of grades of concrete as per 456 : 2000 standard

This construction video tutorial from learning technology demonstrates the grades of concrete on the basis of IS 456 : 2000 standard. As per this standard the grades are categorized in three groups like ordinary concrete, standard concrete and high strength concrete. Here grades range from M10 to M80.

M10, M15 and M20 belong to Ordinary Concrete. M25, M30, M35, M40, M45, M50, M55 belong to Standard Concrete. M60, M65, M70, M75 and M80 belong to High Strength Concrete (HSC).

Here m denotes mix and number denotes characteristic compressive strength of 150 mm cube at 28 days in N/mm2 (Newton per millimeter square). It means if you take compressive test of a cube having dimensions 150 x 150 x 150 mm for 28 days, the value obtained is 10 N/mm2.

All these concrete grades are suitably for PCC work i.e. plain cement concrete work where rebar is not used.

Standard Concrete is generally used in 10 storied and higher buildings and super structures.

High strength concrete is mostly used for designing heavy structures.

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Published By

Rajib Dey

www.constructioncost.co

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Definitions of trade and non-trade cement

This construction video tutorial sheds light on the following topics :-

a. Definitions of trade and non-trade cement
b. Variations among trade and non-trade cement
c. The benefits of non-trade cement over trade cement in big projects as well as governments bodies.

Cement is marketed with two mechanism i.e. trade and non-trade.

The manufacturer directly sells trade cement to the dealers and retailers, who alternately sell to the end consumers. It is a more stable method of vending cement since the manufacturer does not have to take the liability for making sales pitches to the consumer directly. The dealer get incentives to sell the product.

Under this mechanism, all taxes like vat octroi etc are levied when the consumer buys cement with the intension of developing a home and seizing it as his property. Here, the purchaser belongs to a house owner or a petty contractor, whose consumption is insufficient Ex. (200+40vat+30octroi+30profit) = 300/- per Bag in which company earns profit as 30/- and the government earns rest 70/- per bag.

Under non-trade cement mechanism, the manufacturer directly sells to the consumer like a construction company for self usages in project. Here, the cement is not sold to any third party. Here, the dealer is not involved.

It is mostly effective for small scale manufacturers of cement. In non-trade cements, there are not huge overhead costs and for this reason it is economical with regards to trade cements. This type of cement is brought in mass volume from the manufacturer by the consumers like realtors, contractors, etc.

Under this mode, the company only levies the central sales tax on the commodity, borne by the buyer, and provides a form C, that is generally offered to a builder or contractor since he only constructs the projects and delivers to the owner and don’t have to care for its possession after finishing of construction. Generally, in this case the purchaser is a contractor or a builder or developer, whose intake is considerably high as in construction projects.

As for instance if the cost to company for cement is 200/- with zero profit, the non trade price may be (200+20 tax + 15 profit) = 235/- per bag with company making 15/- profit per bag and the government is obtaining 20/- per bag as tax.

To learn more, go through the following exclusive construction video tutorial.

Video Source: Tutorials Tips

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Published By
Rajib Dey
www.constructioncost.co
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Benefits and uses of Light Weight Concrete

Usually, the traditional concrete is made of a heavy material containing density about 2400kg/m3 and strong thermal conductivity. If, the ordinary concrete is used for building up the structure, it can increate the dead weight of the structure and as a result the structure turns out to be heavy. The cost of the structure is also increased significantly.

The light weight concrete is defined as the concrete whose density differs from 300 to 1800 kg/m3.The following methods are applied to build up light weight concrete:

1) By cellular construction.
2) By generating huge quantities of air
3) With the use of no fines concrete
4) With the use of light weight aggregates like expanded clay, shale and slate , fly ash, blast furnace slag etc.

Advantage: The light weight concrete is beneficial for the following reasons :-

a) Because of its low density , it can minimize dead load, enhances the advancement of building and reduces the handling cost.
b) The light weight concrete contains low thermal conductivity. Therefore, in severe atmospheric condition, the type of concrete is mostly recommended.
c) When light weight concrete is used, it provides an opening for industrial wastes like fly ash , slag etc, to get rid of the issue for disposal.
d) It has good resistance capacity against fire.
e) The process for slicing , cutting, drilling or nailing becomes easier for light weight product. It can simplify the construction and repair work.

Uses: Given below, various applications of light weight concrete :-

a) It is extensively utilized as insulator to exterior walls of different types of buildings.
b) It is suitable for erecting load bearing walls, filler wall and partition wall.
c) It is effective for producing pre-cast floor and roof panels and composite walls.
d)It can also be applied for building up in situ composite roof and floor slabs.



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Published By
Rajib Dey
www.constructioncost.co
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