Common thumb rules for civil engineering works

 Thumb Rules is very important for any civil engineer, Site engineer or civil supervisor to obtain instant decisions on the construction site. By applying thumb, the engineers can get the solution with a simple mathematical formula and take proper decisions wherever required. Before applying these thumb rules, it should be kept in mind that the thumb rule can only provide fairly accurate results never the correct results.

The following types of thumb rules for civil engineers are commonly used in construction work :-

Thumb rule for measuring the Concrete Volume relating to the area:
The volume of concrete necessary = 0.038 m3/square feet area.

As for instance, if Plan Area = 40 x 20 = 800 Sq. m., total necessary volume of concrete will be as follow :-
= 800 x 0.038m3 = 30.4m3

Thumb rule for Steel quantity necessary for Slab, Beams, Footings & Columns:
Essential quantity of steel in residential buildings = 4.5 Kgs – 4.75 Kgs / Sq. Ft.
Essential quantity of steel in commercial buildings = 5.0 Kgs-5.50 Kgs/Sq. Ft.

Thumb Rules For Civil Engineers recommended by B N Datta for the Steel quantity that will be applied for several members of the building :-

Proportions of Steel in Structural Members:

1) Slab – 1% of the total volume of concrete
2) Beam – 2% of the total volume of concrete
3) Column – 2.5% of total volume of concrete
4) Footings – 0.8% of the total volume of concrete

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Some important thumb rules for making the layout of any Column

 Guidelines to be followed for making A column layout is created on the basis of the following directions :-

The design of columns should be made with regard to the total forces operating on the structure. In order to avoid errors, there are some important thumb rules which should be followed by every Civil engineer and Architect.

The following three thumb rules should be followed:

1. Size of the Columns
2. Spaces among Columns
3. Alignment of columns

Minimum Size of RCC columns: The size of the columns is based on the total loads operating on the columns which range from axial loads and lateral loads. Large beam spans cause bending moment in the beams as well as in columns which are drawn by the stresses in the beams.

To apply this general thumb rule, presume a structure of G+1 floors high, with standard 6? walls. Least size of an RCC column should not be under 9? x 12? (225mm x 300mm) with 4 bars of 12 MM Fe415 Steel.

The dimension of the column should be 9? x 12? (225 mm x 300mm) with 6 bars of 12 MM Fe500 steel. It is recommended to utilize M20 grade concrete for the structure (ratio 1 part Cement : 1.5 parts Sand : 3 parts Aggregate with 0.5 parts water by volume). It is also suggested to utilize 8 MM stirrups at a span of 150 MM center to center all through the length of column.

This setup of 9? x 12? RCC columns is secured for G+1 Floors.

Spaces (distance) among two columns: To install the above column, a distance of up to 5 meters should be maintained. It is suggested to apply beams of size 9? X 12? (225 MM x 300MM) having a slab thickness of 5? (125 MM) cast in M20 concrete for spans up to 5m. Some other factors like secondary and tertiary spans, point loads and wall loads which should also be taken into consideration. The thumb rules can be useful when the structure is simple.

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Basic differences among RC slab and RB slab

 RC Slab: RC Slab stands for a horizontal structural component of steel reinforced concrete. Generally, the thickness of RC slab varies from 100mm to 500mm. RC Slabs are frequently applied as floorings, ceilings etc. Slabs are supported on two sides only or contain beams on all four sides.

RC slabs are erected with formwork, that is generally created with wooden planks, boards, plastic & steel. In recent times, prefabricated RC slabs are also utilized. RC Slab is also termed as Reinforced Concrete Slab that arranges reinforcement for retaining the strength of the structure. Straight bar and alternative cranked bars are also applied as reinforcement in the RC slabs.

RB slabs: RB slab stands for a reinforced brick slab that is suitable for floorings and ceilings. RB slab is erected with steel reinforcement arranging spacing with the bricks. The construction cost of RB slab is less with regard to RC slab.

An RC slab alias Reinforced Cement slab is found in buildings and in bridge construction. The reinforcement is provided with steel bars which are arranged with some distances according to design and based on the load the slab has to undergo.

An RB slab alias Reinforced Brick slab is ideal for roofs in buildings. It is less costly as compared to RC slabs. The reinforcement is provided with steel bars which are arranged with some distances according to design and based on the load the slab has to undergo.

The distance among the bars is occupied by bricks which are arranged on its edge. The depth of the slab remains 4.5 in. The bars are provided among the bricks in both directions. The cement-sand mortar along with least possible water quantity is used to fill up the distance among the bars.

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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:

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Details guidelines on RCC Staircase Design

 RCC or reinforced concrete structures comprise of various building elements like Footings, Columns, Beams, Slabs, Staircase etc.

These elements are reinforced with steel to increase the strength of the structure. Staircase is considered as one such vital element in a RCC structure.

Given below, the details on several types of staircases and how the design is created for the dog-legged reinforced cement concrete staircase.

Stairs: There are lots of steps in a stair which are organized in a series to provide entry to various floors of a building. As a stair is the only medium for making communication among different floors of a building, the position of the stair should be perfect.

In a residential building, the staircase should remain adjacent to the main entrance.

In a public building, the stairs should be constructed from the main entrance itself and situated centrally, to give rapid entry to the main apartments.

There should be adequate lighting and suitable ventilation for all staircases.

Different types of Staircases - a. Straight stairs, b. Dog-legged stairs, c. Open newel stair and d. Geometrical stair.

RCC Dog-legged Staircase design: In this type of staircase, the subsequent flights mount in opposite directions. The two flights in plan are not detached with a well. A landing is arranged in accordance with the level at which the direction of the flight varies.

Method for Dog-legged Staircase design: Depending on the direction along which a stair slab extents, the stairs are categorized into the following two types.

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Types, applications and benefits of aggregates

 Aggregates are the vital components in concrete. They are granular materials obtained from the natural rocks, crushed stones as well as natural gravels and sands. The aggregates are amalgamated with a binding material in fixed ratios to form concrete.

Aggregates normally capture about 70% to 80% of the concrete volume and they significantly affect the different properties like strength, hardness and stability of the concrete. Aggregates function as fillers or volume increasing components.

Applications of aggregates:

1. They are used as an underlying material for foundations and pavements.

2. They are used as constituents in portland cement concrete & asphalt concrete.

Properties of Aggregate: Aggregate should contain the properties given below -

1. It should be chemically static that means they should not respond to cement or any other aggregate or admixture.

2. It should contain adequate hardness to avoid scratching and erosion in the hardened state.

3. It should contain adequate toughness to sustain impact and vibratory loads.

4. It should be physically strong to carry compressive and normal tensile loads in ordinary mixture.

5. It should not contain impurities, inorganic or organic in nature for which the quality of concrete will be affected significantly.

6. It should have capabilities to produce usable plastic mixture after getting mixed with cement and water.

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Types of Leveling Methods in Surveying

 Leveling is the most generally utilized technique for getting the elevations of ground points comparative with a reference datum and is normally done as a different system to those utilized in fixing planimetric position. The fundamental idea of leveling includes the estimation of vertical separation comparative with a horizontal line of sight. Consequently, it requires a graduated staff for the vertical estimations and an instrument that gives a horizontal line of sight.

The different types of Leveling in ground survey are:

a. Precise or Geodetic Leveling
b. Ordinary or Simple Leveling

Techniques for Leveling

Techniques for leveling might be immediate, for example:

1. Simple Leveling
2. Differential Leveling
3. Profile Leveling
4. Cross Sectioning

5. Reciprocal Leveling
6. Precise leveling
7. Check Leveling
8. Fly Leveling

Or then again might be aberrant, e.g.

1. Trigonometric Leveling
2. Barometric Leveling
3. Hypsometry

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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.

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Some useful tips to work out the length of the bent bars

 While fabricating reinforcing bars with bends, the straight bar is primarily cut to a length that is under the sum of the specified dimensions of the bent bar.

The variation among the detailed length and the cut length belongs to the “bend curvature deduction” and called as various names like gain, creep, and gyp. Usually, the fabricators and programmers get the bend curvature deduction from a bend deduction table.

In the following table 1, the deductions for 45- and 90-degree bends of common bar sizes are provided.

Figure 1 illustrates a No. 8 (No. 25) bar with a standard hook and sides estimating 1 ft 4 in. and 4 ft (400 and 1220 mm). The detailed length of this bar is obtained by summing up the two sides, or 5 ft 4 in. (1620 mm). From Table 1, the deduction for a 90-degree bend on a No. 8 (No. 25) bar is 2-1/2 in. (65 mm). So, in such a case, the cut length of the bar should be 5 ft 1-1/2 in. (1555 mm).

The usual standard for working out the cut length of a bar is along the actual centerline of the bar, that is equivalent to the neutral axis of the bar cross section before bending. The cut length of a bent bar is less than the sum of the finished dimensions due to the following reasons :-

with a easy-to-follow mathematical calculation.

If the exterior fibers of the bar are elongated easily, the inner fibers of the bar are constrained by friction against the bending mandrel, so, the neutral axis shifts inward approaching the mandrel. It is critical to measure this component. The inconsistency arises from computing the lengths on the basis of the actual centerline is not very important.

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Types of Pointing in Brick Masonry Construction

 Pointing is the craft of consummation the issue joints inside the uncovered brick work with a satisfactory cement or lime mortar, to shield the joints from climate impacts, to upgrade the presence of building structure. The joints on the essence of any stone work are generally filled, though the divider is being raised.

Pointing is finished with the accompanying mortar blends:

1. Lime mortar 1: 2 blend (1 lime: 2 sand)
2. Cement mortar 1: 3 blend (1 cement: 3 sand)

Technique for Pointing: All the mortar joints in the brick work are raked out to a profundity of 10-15mm with the assistance of pointings tool. Residue and free mortar are completely cleaned. The joints and the surface are washed with clean water and saved wet for at times.

The mortar is taken in a little dish and the old mortar is squeezed into the joints and loaded up with little trowels to reach the joints. Joints are disposed of flushed, sunk, or raised relying upon necessities, expelling overabundance mortar. The completed work is restored for 3-4 days in instances of lime mortar and for 10 days when cement mortar is utilized.

Types of Pointing: Pointing is characterized by wrapping up. The kind of pointings is choice dependent on the sort of brick work, the idea of the structure and the ideal impact of finish.

Beaded pointing: This kind of pointings gives a generally excellent appearance however is hard to keep up. The raked joints are loaded up with a mortar and completed flush with the essence of the property after which are beaded by a steel thruway with a sunken edge in the middle of the joints.

Flush pointing: In any pointings, joints are raked and they are finished flush with the essence of the block workmanship. The sides are accurately cut. It is the most effortless kind of pointings, which is broadly utilized in brick work. This pointing doesn't give a great look, however it is very strong and it doesn't empower dust, earth to hold up over it.

Recessed pointing: In this sort of pointings, the mortar is kept vertical however inside the outside of the divider with the assistance of reasonable hardware. This sort of pointings is reasonable to withstand crafted by blocks of better surface and better quality mortar.

Rubbed or grooved pointings: In this sort of pointings, the raked joints are topped off flush with face or the moan and crescent indents are framed by an uncommon tool. This kind of pointings is regularly utilized, it improves the appearance of the cry.

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How can you get good natural Ventilation in Buildings

Natural ventilation is the way toward providing air to and expelling air from an indoor space without utilizing mechanical frameworks. It alludes to the progression of outer air to an indoor space because of weight contrasts emerging from natural powers.

There are two kinds of natural ventilation happening in structures: wind driven ventilation and lightness driven ventilation. Wind driven ventilation emerges from the various weights made by wind around a structure or structure, and openings being shaped on the border which at that point license move through the structure.

Lightness driven ventilation happens because of the directional lightness power that outcomes from temperature contrasts between the inside and outside. Since the inside warmth picks up which make temperature contrasts between the inside and outside are made by natural procedures, including the warmth from individuals, and wind impacts are variable, naturally ventilated structures are some of the time called "breathing structures".

As a matter of first importance, it ought to be recalled that natural ventilation is for the most part successful for little houses, not for huge structures. This framework works by giving windows, entryways, little openings and ventilators in a legitimate area of any house.

Importance of Ventilation - Ventilation is important in structures because of these reasons:

1. To evacuate 'stale' air and supplant it with 'natural' air.
2. Assisting with directing inside temperatures.
3. Assisting with directing inside moistness.
4. Recharging oxygen.
5. Lessening the amassing of dampness, scents, microscopic organisms, dust, carbon dioxide, smoke and different contaminants that can develop during involved periods.
6. Making air development which improves the solace of inhabitants.

Types of Ventilation: Broadly, ventilation in structures can be delegated as 'natural' or 'mechanical'. Mechanical (or constrained) ventilation is driven by fans or other mechanical plants. Natural ventilation is driven by pressure contrasts between one piece of a structure and another, or pressure contrasts between within and outside. For more data see Natural ventilation.

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Some vital tips for the selection of proper foundation types

In order to maintain the longevity of a building, the most vital step is to explore foundation types and select the most suitable foundation for your building project.

FOUNDATION TYPES FROM THE GROUND UP: As per the Soil Mechanics in Engineering Practice, a foundation means the lower segment of a building structure that transmits its gravity loads to the earth. This foundation is selected based on the following factors -

1. Ground/soil conditions
2. Types of loads from the building structure

GROUND/SOIL CONDITIONS - Soil investigation is performed for the following purposes :

• Nature and type of soil
• Depth of various layers of soil
• Bearing strength of the soil at different levels
• Level/slope of the ground

As for instance, when the soil adjacent to the surface does not have the capacity to sustain the structural loads, hard strata (soil layer with adequate load bearing strength) should be selected and most often deeper foundations are essential. Otherwise, with the existence of homogeneous stable ground, a shallow foundation is suitable.

LOAD TYPES FROM BUILDINGS: Loading conditions severely impact the selection of foundation types which are based on the type of building for your project, location/ecological factors and the type of structural construction materials effective for your project. The following factors are mainly responsible for raising loads and constructing deeper foundations:

• High-rise/multi-story buildings
• Susceptibility to strong winds or earthquake zones
• Reinforced concrete buildings

PUT THE PIECES TOGETHER: As soon as the soils are examined and loads types are established for the building project, then put the pieces together and opt for the best foundation type for the project. These main foundation types comprise of the following :-

• Spread/wall footings.
• This type of foundation is applicable where the base is broader as compared to a normal load bearing wall.
• The broader base allocates the weight from the building structure across a larger surface area and enhances the longevity of the building.
• Drilled pier/deep foundation.

• This type of deep foundation is useful for transmitting greater loads from the building structure to hard rock strata.
• This type of foundation can minimize the amount of ground disturbance whereas provides protection against earthquakes and wind forces. It is also suitable where highly expansive soils exist near surface.
• Post-tensioned slab foundation.
• This type of foundation extends over the entire area of the building to sustain loads from columns and walls.
• It can be utilized on expansive soils.

Source: http://constructioncost.co/

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