Some popular IS Codes in building construction

A code demonstrates the consent of opinion of experienced engineers and professionals.

The codes offer the instructions for the design and construction of structures. They are modified repeatedly to take account new progress (in research, materials, construction methods, etc..) & experience obtained from earlier design practice, behavior of prevailing structures, and collapsing of structures.

Codes include proposed loads for a specified locality, and proposed safeguard for fire and corrosion. They also comprise of rules to manage the processes in which loads should be employed as well as design rules. These rules should be available as detailed recommendations or by reference to other standards that offer specific design rules. The codes should be treated as supports to the design that comprise of stress levels, design formulae, and recommendations for good practice.

The codes primarily offer the following functionalities :-

• They guarantee sufficient structural protection, by designating specific crucial minimum requirements for the design.
• They help the designer in the design method. Often the analysis are accessible like simple formula or charts.
• They make sure to maintain uniformity among several engineers.
• They safeguard the structural engineer from disputes, through codes in various cases do not provide legal protection.

Given below, the detail lists of IS codes which are commonly utilized for Building Construction Practices.

IS 883:1994 Code of practice for create the design of structural timber in building
IS 965:1963 Identical metric units for scales, dimensions and quantities in general construction work.
IS 1414:1989 Code of practice for the settlement of wall coverings.
IS 1477(Part 1):1971 Code of practice for painting of ferrous metals in buildings: Part 1 Pre treatment.
IS 1477(Part 2):1971 Code of practice for painting of ferrous metals in buildings: Part 2 Painting.
IS 1597(Part 1):1992 Code of practice for construction of stone masonry: Part 1 Rubble stone masonry
IS 1597(Part 2):1992 Code of practice for construction of stone masonry: Part 2 Ashlar masonry

IS 1634:1992 Code of practice for design and construction of wood stairs for houses
IS 1649:1962 Code of practice for design and construction of flues and chimneys for domestic heating appliances
IS 1834:1984 Specification for hot applied sealing compound for joints in concrete
IS 1838(Part 1):1983 Specification for preformed fillers for expansion joint in concrete pavement and structures (non extruding and resilient type): Part 1 Bitumen impregnated fibre
IS 1838(Part 2):1984 Specification for preformed fillers for expansion joint in concrete pavement and structures (non extruding and resilient type) Part 2 CNSL Aldehyde resin and coconut pith
IS 1905:1987 Code of practice for structural use of unreinforced masonry
IS 1946:1961 Code of practice for use of fixing devices in walls, ceilings and floors of solid construction

To get more detail lists, go through the following link enginneringcivil.blogspot.com



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Some useful guidelines for the calculation of concrete costs

Besides, considering the price of concrete per yard (or meter), cost calculation of new concrete includes other items like surface prep, formwork, reinforcing materials, and finish work, as well as the cost of the ready-mix concrete, that will be included to the total price of the concrete work. The Costs for specific items differ location wise or from site to site, but an approximate estimate can be prepared with some average amounts.

Cost Per Yard of Ready-Mix Concrete

The most vital item refers to the price of concrete, whether ready-mix concrete or other concrete material are utilized. Local ready-mix concrete suppliers can provide you the quotes based on the project specifications and the job location. Concrete pricing is generally stated per cubic yard or cubic meter (metre). For an average estimating purpose, utilize $77 per cubic yard.

Cost of Concrete Sub-Grade Work

When the concrete is set over soil, it is required to grade or make the surface ready for the concrete. Pricing for this includes the expenses associated with grading, compacting soil, excavating, trenching, and other components. As a good average, it is recommended to utilize $65 per hour of work required to set up the surface, supposing that the surface is leveled over 75 percent and no special work is necessary to make the site ready.

Costs for Extra Sub-Grade or Site Work

If the surface is unleveled, it is required to incur expenses for additional site work like excavating and filling with proper material or eliminating a soft spot on the terrain to prepare it for resisting structural loads. Based on the distance from where the sand will be arranged or any other proper fill material, it could put in over $10 per cubic yard or meter to your estimate. Another cost may incur for polyurethane plastic or vapor barrier essential to be set up prior to concrete placement.

Cost of Concrete Formwork

Developing concrete forms generally indicate a vital part of the total cost of concrete work, since it is one of the most time-consuming tasks of the job. It is required to recognize the type of formwork to be utilized as well as how it will be set up, and whether the form materials will be purchased or rented. Other related costs may contain a crane or other equipments which are applied to shift the form materials, form release product, re-processing form materials, and the cost to repair forms after various applications.

On average, formwork costs at $1.10 per square foot of the concrete area. It is calculated for a square or rectangular area. The cost is increased for concrete, if the formwork is rounded or contoured.

Cost to Finish Concrete

Concrete prices change considerably based on the type of finishing stated in the design. Concrete is finished several ways like smooth surface, exposed aggregate surface, or stamped concrete finish. Some surfaces may need only a strike-off and screed to perfect contour and elevation, whereas for others surfaces, a broomed, floated, or troweled finish should be specified. To calculate the finishing in your concrete pricing analysis, add $0.75 per square foot or perhaps more, based on the intricacy of the specified finish. The cost of any curing compound or testing services required should also be considered.

Cost of Concrete Reinforcement

Most concrete comprises of some type of reinforcement, like rebar, wire mesh, plastic mesh, or fiber which are included to the concrete mix to make the strength and crack-resistance better. Standard reinforcing materials can include roughly $0.18 cents per square foot. This number is greater for large-diameter rebar or other special reinforcement.



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Details of Sieve Analysis Method

Sieve analysis is conducted to establish the particle size distribution of the coarse and fine aggregates. This is performed with sieving the aggregates according to IS: 2386 (Part I) – 1963. Here, various types of sieves are applied as recommended by the IS code and then the aggregates are passed through them and thus the particles with different sizes are obtained which are abandoned on various sieves.

The following equipments are utilized for sieve analysis.

i) A set of IS Sieves of sizes – 80mm, 63mm, 50mm, 40mm,31.5mm, 25mm, 20mm, 16mm, 12.5mm, 10mm, 6.3mm,4.75mm, 3.35mm, 2.36mm, 1.18mm, 600µm, 300µm, 150µm and 75µm.

ii) Balance or scale with a precision to calculate 0.1 percent of the weight of the test sample. The sample for sieving is created from the bigger sample either by quartering or with the help of a sample divider.

Sieving Test Method as per British standard

Materials Required
Specimen, sieve shaker, BS410 Standard sieves, 0.1g accuracy balance, oven, porcelain dish and spatula, receiving pan, cleaning brush and clock.

Method:
Cleanse the sieves of sieve shaker with cleaning brush to check whether any particles are blocked in the openings.

Note down the weight of each sieve and receiving pan.
Dry the specimen in oven for 3-4 minutes to obtain the dried specimen (overlook, if the specimen is already dried).
Weigh the specimen and note down its weight.

Place the sieves in such a manner that the smaller openings sieve remains to the last and larger openings sieve remains to the top. (Just, organize them to the ascending order of sieve numbers – No.4 sieve on top and no.200 sieve at bottom).

Retain the weight recorded specimen on the top sieve and then provide the complete sieve stack on the sieve shaker along with the lid and receiving pan.
Let the shaker to function 10-5 minutes – Utilize the clock here.
Detach the sieve stack from the shaker and note down the weight of each sieve and receiving pan individually.

Download the following sample sheet for sieve analysis.



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The construction process and benefits of cavity walls

Cavity wall stands for a double wall that comprises of two individual walls of masonry known as skins or leaves which are detached with an air space and connected jointly through metal ties at proper distances.

These walls are normally used as outside walls but sometimes used also as interior walls because of good sound.

Construction Methods of Cavity Wall

The two leaves of a cavity wall contain same thickness when it belongs to a non load bearing wall or the inside leaf becomes thicker as compared to exterior leaf to comply with the structural needs.

The interior and exterior skins of the wall are sufficiently knotted jointly with special wall ties involving minimum five ties per square meter of wall.

The cavity wall should not remain under 40mm nor over 100 mm in width.

A vertical damp proof course should be provided at window and door reveals so that moisture can not penetrate in the wall. The damp proof course should be adaptable.

Building Regulations For Cavity Wall
As per the norms of building codes, the double wall should be normally 265 mm or 275 mm thick and comprises of 102.5 mm interior and exterior skins and 60-70 mm cavity (sufficient for 2 storied domestic building).

The interior leaf should be raised to 215 mm or more in thickness encountering heavier load or floors. For stone faced buildings, the exterior leaf should be 103-206 mm and interior leaf should be 102.5 mm. The width of cavity in between differs from 50 – 70 mm.

Benefits of cavity walls

1. In these types of walls, there are no scopes for entering of moisture from the exterior wall to the interior wall.
2. The layer of air in the cavity does not transmit heat and minimizes the transition of heat from the exterior face to interior face.
3. It functions as damp barrier and lessens the cooling cost of the building.
4. The cost of building up a 275 mm cavity wall will be low as compared to build up a 328 mm solid wall.
5. It is inexpensive as compared to exterior or interior wall insulation.
6. It retains the thickness of the existing wall.
7. Minimum disruption is required for set up.
8. It can minimize condensation significantly.



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How to calculate the self weight of the different structural elements

A building load belongs to a force that should be confronted by the house frame. The frame should be designed in an efficient manner to resist eight of these loads ranging from wind, earth, and snow devoid of catastrophic stress on the structure.

Given below, the detail calculation method of self weight for the structural components:

a. Beam: It is applicable to different types of shapes like rectangular/square/tee/trapezoid for measuring the weight.
Weight of member = cross section area of member x length of member x RCC density
Suppose, the width is taken as 0.3 m and depth is taken as 0.45 m for the beam section with 5 m clear length & material density = 25 kn/m3 (for RCC), the weight should be as follow :-
Weight of beam = (0.3 x 0.45) x 5 x 25 = 16.875 Kn
The above calculated weight of 16.875 Kn stands for the total weight that should be transformed into Uniformly Distributed Load (UDL) by dividing the total weight with member length.
UDL = 16.875/5 = 3.375 Kn/m

b. Column: While measuring the self-weight of a column, the terminology of member length should be converted to member height & the weight of column should be computed as point load only its conversion in UDL is not necessary.

c. Slab: For RCC slabs, the weight of roof slabs is employed as invariable pressure in Kn/m2. For making analysis, a 1 m x 1 m square section is taken into consideration & the volume of the RCC is measured & then the same is multiplied with the density for derivation of pressure in kn/m2.

Weight of slab = (1 x 1 x slab thickness) x RCC density

In the above formula as (1 x 1) doesn’t impact the estimate thus it can be further clarified as follow :-
Weight of slab = slab thickness x RCC density

If the thickness of the slab is 0.15 m, then the estimate is done as follows :-
Weight of slab = 0.15 x 25 = 3.75 Kn/m2

In the above estimate of RCC slab weight further supplementary load resulting from floor finishes should be generally taken into consideration for stone/cement floorings as 0.75 kn/m2 to 1.5 kn/m2.

The U-value unit is the inverse those of R-value:

Disposition of slab load on supporting beams: Based on the placement of the beams (square or rectangular) triangular or trapezoidal shape distribution is performed. As for instance, for a rectangular slab of 6 m x 4 m the longer side beams distancing among A-B & D-C will bear the load of related trapezoidal portion while the shorter span beams distancing among A-D & B-C will support weight of roof slab arise out of the related triangular region.

Load on 6 m span = area of trapezoid x thickness of slab x density
Load on 6 m span = 8 x 0.15 x 25 = 30 Kn = 30 / member length = 30/6 = 5 Kn/m
The above estimated load of 30 Kn can be again transformed to UDL of 5 kn/m by dividing it with member length.
Load on 4 m span = area of triangle x thickness of slab x density
Load on 4 m span = 4 x 0.15 x 25 = 15 Kn = 15 / member length = 15/4 = 3.75 Kn/m

To get more details, go through the following article civilengineeronline99.blogspot.com

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Details about R-value and U-value of Concrete Slab

The conduction of heat regarding the materials utilized in its construction is measured with the thermal conductivity coefficient alias k-value (W/m.K), of the materials used in its construction. It belongs to the rate at which heat moves through a material among points at dissimilar temperatures.

The thermal resistance alias R-value (m2K/W), is computed by dividing the thickness of the material (in metres) with the k-value. From this the thermal transmittance alias U-value (W/m2.K) concerning a building material is measured like the inverse of the sum of the R-values of the component parts and adjoining air layers.

R-value stands for the estimation of concrete slab (or other material) strength to counter heat flow i.e. it calculates the potency of insulation or thermal resistance. However, U-value stands for the estimation of heat transmission throughout concrete slab from ground into the closed space or oppositely.

Since, thermal insulation fluctuates contrariwise with density, lower density concrete offers superior insulation as compared to greater density concrete. With the purpose of determining the strength of the reinforced concrete slab to withstand heat transfer, it is necessary to estimate R-value and U-value of the reinforced concrete slab under consideration.

The method for estimating R-value for Concrete Slab: A perfect R-value for a normal concrete slab is computed with an R-value, the thermal resistance per inch of thickness, among 0.1 and 0.2 and multiplying it times the slab thickness. The value of R is determined with the following equation provided by ASTM C 168:

Here, the temperature variation (among exterior and interior of concrete slab) is provided in degrees Fahrenheit, the area is given in square feet, the time in hours, and the heat loss in Btus.

ASTM C 168 also offers two supplementary expressions to measure R-value and is available in ASTM C 168 document.

The R-value imperial unit and metric unit are given below:

Computation of u-value for Concrete Slab

The U-value for a concrete slab (and any other building material) stands for the inverse of its R-value and is computed with the formula given below:

The U-value unit is the inverse those of R-value:

Note: There is difference among the American Standard and European Standard for R-value and U-value. Therefore, to transform an American R-value into a European U-value, divide 1 with the R-value, then multiply the result by 5.682 whereas transforming a European U-value to an American R-value, multiply with 0.176, then divide 1 by the result.



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How to design rectangular and T shape beam

Beams are defined as members which are exposed to flexure. So, it is important to give attention to the analysis of bending moment, shear and deflection.

When the bending moment operates on the beam, bending strain is created. The resisting moment is formed with internal stresses. Under positive moment, compressive strains are developed in the top of the beam and tensile strains in the bottom.

Concrete is weak against tensile strength and it is not perfect for flexure member by itself. The tension side of the beam will collapse prior to failure of compression side when beam is exposed to a bending moment devoid of the reinforcement. To resolve this issue, steel reinforcement is provided on the tension side. The steel reinforcement withstands all tensile bending stress as tensile strength of concrete is zero when cracks are formed.

Rectangular beam

Accept the depth of beam with the ACI code reference, least thickness until the deflection is considered.
Accept the beam width (ratio of width and depth is approx 1:2).

Calculate self-weight of beam & design load.
Work out factored load (1.4 DL + 1.7 LL).
Calculate design moment (Mu)
Work out maximum possible nominal moment for singly reinforced beam (φM n ).

Determine reinforcement type by making comparison between the design moment (M u ) and the maximum possible moment for the singly reinforced beam (φM n ). If φM n remains under Mu, the beam should be designed as a doubly reinforced beam otherwise the beam should be designed with tension steel only.

Find out the moment strength of the singly reinforced section (concrete-steel couple).

Calculate the necessary steel area for the singly reinforced section.
Determine an essential residual moment, deducting the total design moment and the moment capacity of the singly reinforced section.
Calculate the extra steel area from the required residual moment.
Calculate the total tension and compressive steel area.
Design the reinforcement with the selection of the steel.
Verify the actual beam depth and assumed beam depth.

T-shape Beam

Calculate the design moment (Mu ).
Presume the effective depth.
Choose the effective flange width (b) depending on ACI criteria.

Workout the practical moment strength (φM n ) anticipating the total effective flange is supporting the compression.

When the practical moment strength (φM n ) is greater than the design moment (Mu ), the beam is measured as a rectangular T-beam with the effective flange width b. If the practical moment strength (φM n ) is not more than the design moment (Mu ), the beam will operate as a true T-shape beam.

Determine the approximate lever arm distance for the internal couple.
Work out the approximate required steel area.

Design the reinforcement
Verify the beam width
Calculate the actual effective depth and analyze the beam



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