Some crucial factors a civil engineer should follow

This construction video tutorial sifts through some vital factors which should be abided by a civil engineer to apply them in the jobsite.

The factors are discussed in below :-

Compressive strength of bricks should be 3.5 N/mm2

Water immersion of bricks should not surpass 15%

Free fall of concrete is permissible up to 1.50 m

Lowest thickness of slab is 125 mm

Longitudinal reinforcement should not be under 0.8% and over 6% of gross C/S

Lowest bars required for square column is 4 Nos and for circular column is 6 Nos

If the bars contain diameter over 36 mm., lapping is not permissible

Compressive strength of bricks is 3.5 N/mm2

Earthwork excavation toward basement over 3 m should remain in stepped form

Cement should be preserved in dry places on a raised platform roughly 200 mm

Electrical conduits should not be set in column

For more information, watch the following construction video.

Some crucial factors a civil engineer should follow

Read more

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Advertisements

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

Get some useful tips to conduct your leveling survey at home

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

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

Basic differences between Development length and Lap Length

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Basic differences among Prismatic Compass and Surveyors Compass

Compass belongs to an instrument that plays an important role to workout the direction of a survey line relative to magnetic north-south.

The magnetic north-south direction is treated as the reference direction and it is known as meridian (reference direction) and the angle among the line and the meridian is known as bearing. The compass is applied for calculating the direction of a line to simplify the surveying process significantly.

The variations among prismatic and surveyor’s compass are given below :-

Prismatic Compass

1. Graduation circle is attached to a broad type needle. Therefore, it will not revolve with the line of sight.
2. A prism is situated at viewing end.
3. Sighting and reading are performed concurrently.
4. The magnetic needle does not perform like an index.
5. The graduations are in whole circle bearing.
6. Graduations are pointed inverted as its reflection is examined via prism.
7. The reading is captured through a prism.
8. Tripod may or may not be applied. It can be persisted with a stretched hand also.

Surveyors Compass

1. Graduation circle is attached to the box. Si, it revolves with the line of sight.
2. No prism exists at viewing end except for a slit.
3. It is not possible to perform sighting and viewing all together.
4. Magnetic needle functions as index at the time of reading.

5. The graduations remain in quadrantal system.
6. Graduations are pointed directly. They are not inverted.
7. The reading is captured by directly viewing from top glass.

8. Tripod is necessary for being applied.

Basic differences among Prismatic Compass and Surveyors Compass

Read more

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

How to examine verticality of structure throughout building construction

The verticality works should be examined at the time of building up construction at various stages like during setting up vertical formworks of columns and transmitting levels up successive floors of multi storey structures.

Some useful processes to check verticality of structure throughout building construction
1. Plumb-bob technique
2. Spirit level
3. Theodolite
4. Optical plummet

1. Plumb-Bob Technique: The purpose of this technique is to make sure that constructions are plumb or vertical. It’s application is also found in surveying to set up the nadir regarding gravity of a point in space.

Plumb-bob comprises of a weight with pointed tip on the bottom that is tied to the end of a string. The heavy weight will cling under gravity and produce a precise vertical line that is known as plumb line.

This method is very effective for examining or managing vertical line of structural elements especially indoors like lift shaft. Besides, it is also utilized to check the verticality of foundation, walls, and columns.

The plumb line or vertical line of plumb-bob is affected by wind force and the perfectness is not maintained. It is possible to minimize small to medium lateral movement of plumb-bob efficiently by moistening it in oil or water.

In case the height of structural member is broad, then the string can be substituted with a long wire, but precautions should be plasticized to get rid of imposing risks to the personals functioning under.

2. Spirit Level Method: This tool is used for managing verticality of small scale works; as for instance inspection of formworks and door frames. If spirit level is applied for guess verifications, then it is necessary to examine the verticality with more precise method.

3. Theodolite Method: Theodolite is considerably robust instrument that is utilized to examine verticality works throughout construction providing proper preciseness.

It is useful for examining or managing verticality of towers, wall, foundation and columns specially large number of columns along a one grid line.

The slope can be calculated out of plumb line of the member with Theodolite in conjunction with a tape.

The following methods are utilized to examine column verticality:

Install the digital Theodolite to the center on a peg that is set up 500 mm from the column grid.
Once the Theodolite is installed perfectly the laser beam will be activated and put it to the steel tape that is retained to the formwork.
The reading of the steel tape is captured via the telescope.
Capture the readings of two positions at the equivalent level on both top and bottom levels of the formwork. Any curvature on the surface is easily found by capturing two readings at the same level.

4. Optical Plummet Method: It belongs to an instrument that sight directly down or directly up. Optical plummet contains an automatic compensator that considerably enhances its perfectness with regards to other methods which are applied for managing verticality.

How to examine verticality of structure throughout building construction

Read more

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Some vital properties of concrete for mix design

While designing the reinforced concrete structure, the designer should concentrate on the following properties of concrete in its harden state.

COMPRESSIVE STRENGTH: At the time of making the design of the buildings and other structures, the compressive strength of concrete is applied as the most common performance measurement.

Compressive strength of concrete is affected by several factors like water-cement ratio, cement strength, quality of concrete material, quality control throughout production of concrete etc.

Concrete compressive strength for general construction fluctuates from 15 MPa (2200 psi) to 30 MPa (4400 psi) and elevated in commercial and industrial structures.

Compressive strength is a vital factor to evaluate the performance of the material throughout service conditions. The compressive strength of concrete is decided in batching plant laboratories for each batch to retain the optimal quality of concrete throughout casting. The strength of concrete is essential to work out the strength of the members. Concrete samples are casted and tested under the action of compressive loads to find out the strength of concrete.

TENSILE STRENGTH: Tensile strength is an important property of concrete since concrete structures prone to tensile cracking because of different types of effects and applied loading itself. Tensile strength of concrete is very low with regard to its compressive strength.

Because of the complexity in employing uniaxial tension to a concrete specimen, the tensile strength of the concrete is obtained by indirect test methods like split cylinder test and flexure test.

Tensile strength of concrete = 1/10 times of compressive strength
With adherence to IS: 456, the tensile strength of concrete is measured from the compressive strength with empirical relation provided by:
Flexural strength: fcr=0.7√fck N/mm2

MODULUS ELASTICITY: The modulus of elasticity of concrete belongs to a function of the modulus of elasticity of the aggregates and the cement matrix and their relative proportions. The elastic modulus of the hardened paste may come in the order of 10-30 GPa and aggregates about 45 to 85 GPa.

 The strength of concrete is mainly based on the relative proportion and modulus of elasticity of the aggregate.

To determine the exact value of elastic modulus of a concrete batch, laboratory test should be carried out. There also exist some empirical formulas which are arranged with different code to get the elastic modulus of Concrete. These formulas are derived on the basis of the relationship among modulus of elasticity and concrete compressive strength. One can easily get an rough value of modulus of elasticity of concrete by applying 28 days concrete strength (f’c) with these formulas.

It can be measured with following formula for normal density concrete:
E = 57,000 (fc’)^0.5
The result will be produced in psi.
fc’ stands for the 28 days cylinder crushing strength in psi.

Modulus of elasticity of concrete is affected by the various factors like type of the aggregates used, type of cement and Mix proportions.

SHRINKAGE OF CONCRETE: It stands for a physical property of concrete. The volumetric variations of concrete structures occur because of the loss of moisture by evaporation is defined as concrete shrinkage or shrinkage of concrete. It is a time-dependent deformation that decreases the volume of concrete devoid of the influence of external forces.

This shrinkage leads to surge in tensile stress, that results in cracking, internal warping, and external deflection, before the concrete has to undergo any type of loading.

Water content in concrete considerably impacts the shrinkage. The IS: 456-2000 suggests the total shrinkage strain as 0.0003 when there is no test data. Drying shrinkage in plain concrete leads to surface cracks. The deflections of reinforced concrete members is also influenced by the shrinkage of concrete.

CREEP OF CONCRETE: Creep is one of the fundamental property of concrete. It is very crucial for designing of concrete structure because in concrete the microstrains of creep fluctuates from 400 to 1000 x 10 -6

Creep is described as the elastic and long-standing deformation of concrete under a continuous load. Normally, a long term pressure alters the shape of concrete structure and the deformation is found along the direction of the applied load.

Creep stands for the time dependent deformations of concrete under permanent loads (self weight), PT forces and permanent displacement.

The creep is affected by the several factors like creep concrete mix proportion, aggregate properties, age at loading, curing conditions, cement properties, temperature, stress level.

COEFFICIENT OF THERMAL EXPANSION: The coefficient of thermal expansion of concrete is impacted by the type of aggregate applied in concrete and it is necessary for making the design of structures like chimneys, water tanks, silos etc. The values provided in IS:456-2000 are as follow :-

Type of Aggregate – Coefficient of Thermal Expansion for Concrete

Quartzite – 1.2 to 1.3 x 10-5
Sandstone – 0.9 to 1.2 x 10-5
Granite – 0.7 to 0.95 x 10-5
Basalt – 0.8 to 0.95 x 10-5
Lime stone – 0.6 to 0.9 x 10-5

For more: http://constructioncost.co/some-vital-properties-of-concrete-for-mix-design.html

Some vital properties of concrete for mix design

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Various types of supports for loads

Roller Supports: Roller Support Example in a CraneRoller supports can be revolved freely as well as translated over the surface upon which the roller is situated.

The surface may come in different forms like horizontal, vertical or slopped at any angle. Roller supports are generally situated at one end of long bridges in the sort of bearing pads. This support facilitates bridge structure to stretch and contract as per modifications of temperature and devoid of this expansion the forces can rupture the supports at the banks.

This support does not have the capacity to withstand the lateral forces. Roller support is also utilized in frame cranes in heavy industries, the support can pass on toward left, right and rotate by withstanding vertical loads. In this way, a heavy load can be transmitted from one place to another horizontally.

Hinge Supports: With the hinge support, it is possible to withstand forces which operate in any direction of the plane. This support does not have any resistance capacity against rotation. The horizontal and vertical component of reaction is found with equation of equilibrium. Hinge support is also applied in three hinged arched bridges at the banks supports even as at the center internal hinge is introduced. It is also employed in doors to create only rotation in a door. Hinge support minimizes sensitivity to earthquake.

FIXED SUPPORT: Fixed support has the strength to withstand vertical and horizontal forces as well as moment as they prevent both rotation and translation. They are also called rigid support. To maintain longevity of a structure, a fixed support should exist.

A flagpole at concrete base is the instance of fixed support. In RCC structures, the steel reinforcement of a beam is implanted in a column to create a fixed support. The instances of fixed supports are all the riveted and welded joints in steel structure.

PINNED SUPPORTS: Pinned Supports – A pinned support has the similarity with hinged support. It can withstand both vertical and horizontal forces devoid of a moment.

It facilitates the structural member to rotate, but not to translate in any direction. Many connections are taken as pinned connections although they might withstand a small amount of moment in reality. It is known fact that a pinned connection can facilitate rotation in only one direction by providing resistance to rotation in any other direction.

Ideal pinned and fixed supports are not often detected in practice, but beams supported on walls or simply connected to other steel beams are treated as pinned. The distribution of moments and shear forces is dependent on the support condition.

INTERNAL HINGE: Interior hinges are mostly used to join flexural members at points other than supports.

In some cases, it is purposely introduced with the intension that additional load breaks this weak zone in spite of damaging other structural elements.

Source: aboutcivil.org

Various types of supports for loads

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Different categories of sands and their applications

The sand is mainly applied for rock particles which mainly vary in grain size among 2 mm and 1/16 mm. In composition, they are primarily an oxide of silica SiO2.

Mineralogically, they mostly include broken grains of mineral Quartz (SiO2) that is formed due to the crashing of sandstones and equivalent rocks.

Categorization of Sands: Sands are classified variously on the basis of their Based on the mode of origin, composition, and grain size, the sands are differently categorized.

The mode of origin: With adherence to the mode of origin, there are three types of sands like pit sands, stream sands and marine sands..

The pit sands are generally sharp and angular in outline. Winds generally deposited them and develop accumulations in soils covered by clays. Good quality mortars can be produced from these sands by purifying and cleansing them properly.

The river sands come about large accumulations along the base and banks of all the rivers in plains and semi-hilly areas. The shape of the sand grains in river sands appear almost round (because of significant movement in river waters).

These do not contain clay, salt encrustations, and organic impurities. So, these are frequently utilized to produce mortars, plasters, and concrete.

The marine sands are found on beaches and along the seashores. Similar to river sands, they comprise of rounded grains of quartz. There are some problems with these sands as their grains are mostly wrapped with coatings of salts from sea water.

These salts can’t be separated easily. So, if these salts are utilized with mortars or concrete, a reaction occurs with the binding materials and produce lots of difficulties. Beside, the salt encrustations are often hygroscopic, it means they consume moisture from the atmosphere.

It also leads to delayed setting, dampness. Besides, efflorescence may also happen in mortar or concrete that is formed with these sands. Therefore, the quality of marine sands is substandard and should not be recommended. But, in case of requirements, marine sands should be cleansed perfectly prior to utilize them.

In order to learn how sand is categorized on the basis of composition and grain size, go through the following construction article.

Source: civilseek.com

 

Different categories of sands and their applications

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

Various types of Design Loads on Bridges, Highway & Rail Bridge

While going to deign any bridge, the tasks like computation of Design Loads and loading bridge model are very important. Given below, some crucial loads which should be taken into consideration at the time of creating the design of a bridge.

Dead Load – “Gravity loading because of structural parts of bridge”

Dead load comprises of permanent gravity forces because of structural Elements. It is basically measured as the product of volume and material density. Normally, self-weight is employed in the analysis model with the self-weight option of the analysis software. This makes the calculation step simple.

Superimposed Dead Load – “Dead Gravity loading because of non-structural parts of bridge”

Superimposed dead loads stand for gravity loads that include other permanent items ranging from parapets and road surfacing and other non-structural and architectural attachments to the bridge. Such items last long but should have been modified during the lifetime of the structure. It has similarity with self-weight and it is measured as the product of volume and material density.

The most crucial item of superimposed dead load belongs to the road pavement or surfacing. It is not atypical for road pavements to become gradually thicker over a number of years since every new surfacing is just placed on top of the one before it. Therefore, specifically high load factor is employed to road pavement.

Imposed traffic Loading – “Because of road or rail vehicles”

Imposed traffic loads contain those forces which are produced with road or rail vehicles on the bridge. Bridge traffic can be vehicular, rail or pedestrian/cycle or genuinely any combination of these. The type and strength of the design vehicle alters on the basis of the design code. As for instance, HL-93 is used in AASHTO design code.

Bridge traffic loading is frequently monitored by trucks whose weights significantly surpass the maximum legal. Bridge traffic loading is used with the notional lanes which do not depend on the actual lanes. Eurocode normal loading comprises of invariable loading and a pair of four wheels in a single lane.

To examine the dynamic effects of traffic, the vehicular loads are multiplied with an impact factor frequently.

Pedestrian and cycle track – “Gravity loading because of non-vehicular traffic”

Bridge codes normally indicate a basic intensity for pedestrian loading. Again intensity is based on the design code, it is 5 kN/m2 in the Eurocode and the British standard and 4 kN/m2 in the American code.

To get more detail information, go through the following link. engineeringcivil.org

Various types of Design Loads on Bridges, Highway & Rail Bridge

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~

How to make the design of a Foundation

Foundation is the portion of structure underneath plinth level up to the soil. It is directly connected with soil and it transfers the load of super structure to soil. Normally, it is located under the ground level.

If some portion of foundation is situated over ground level, it is also enveloped with earth filling. This part of structure is not in touch with air, light etc, It is considered as the concealed part of the structure.

Depth of Foundation: Depth of foundation is based on the following points-

1. Sufficient bearing capacity should exist
2. Depth of shrinkage and swelling for of clay soils, because of change in climate that may lead to appreciable movements.
3. Depth of frost penetration for fine sand and silt.
4. Chances of availability of excavation
5. Depth of ground water table
6. Practical lowest depth of foundation should not be under 50 cm. to facilitate subtraction of top soil and deviations in ground level.
7. So, the desired depth of foundation should vary from 1.00 meter to 1.5 meter from original ground level.

Footing: Footing belongs to a structure that is built up in brick work, masonry or concrete under the base of a wall or column for dispersing the load over a extended area.

Width of Foundation/Footings

The width of footings is based on the structural design. For light loaded buildings like houses, flats, school buildings etc which do not contain over two stories, the width of foundation is provided below :-

1. The width of footing should not be under 75 cm for one brick thick wall.
2. The width of footing should not be under 1 meter for one and half brick wall.

Various methods in Foundation Work: The following methods are involved in the foundation works –

1. Excavation of earth work in trenches for foundation.
2. Work out cement concrete.
3. Set the footing for raft or column construction.
4. Arrange Anti termite treatment.

5. Set Brick work up to plinth level.
6. Set Damp proof course on the walls.
7. Refilling of earth around the walls
8. Refilling of earth in the building portion up to the desired height as per plinth level.

for more: http://constructioncost.co/how-to-make-the-design-of-a-foundation.html

How to make the design of a Foundation

~~~~~~~~~~~~~~~~~~~~~~~~
Published By
Arka Roy
http://www.constructioncost.co
~~~~~~~~~~~~~~~~~~~~~~~~