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Explanation:

Pain concrete:

• Plain concrete is brittle and it has low tensile strength and high compressive strength
• Innately, this mechanical property of concrete depends on the synergistic contribution of its components which are water, cement, and aggregate.
• At the appropriate ratio of water and cement, plain concrete structures have high resistance to compression but a low resistance to tension.
• To improve tensile strength of concrete reinforcement is provided on tensile zone.
• Reinforcement in concrete is generally provided in the form of steel but various other form of reinforcement can be provided to improve tensile strength of concrete such as fibers, bamboo etc.​

Explanation:

Lever arm of the beam:

• Lever arm is the perpendicular distance between the line of action of the couple forming compressive and tensile force in a Reinforced concrete section.
• The lever arm plays vital role in the calculation of the moment of resistance, maximum and minimum reinforcement ratios etc. thus influencing the entire design of a RCC section.

Let us take a common example of Reinforced concrete section subjected to bending as shown below:

The section above the neutral axis is in compression whereas the section below the neutral axis is in tension. The stress diagram in working stress method is assumed to be linear, hence the compressive force will act at one third of the neutral axis from top. The entire tensile stress is taken by steel alone (one of the assumption), hence the tensile force will act at the level of steel.

Therefore, liver arm becomes:

\({\rm{Liver;arm}} = {\rm{d}} - \frac{{\rm{n}}}{3}\) = \(\frac{3 \mathrm{~d}-\mathrm{n}}{3}\)

Where, d = effective depth of the section and n = neutral axis depth

Concept:

Method of analysis of indeterminate structures:

Method of section for indeterminate truss:

• The method of sections can be used to analyze indeterminate trusses also, but it needs to be combined with other methods to obtain a complete solution.
• For an indeterminate truss, the method of sections alone cannot determine all the unknown forces in the truss. However, it can be used to determine the unknown forces in some of the truss members.
• To obtain a complete solution for an indeterminate truss using the method of sections, it is necessary to combine it with other methods, such as the method of joints, method of consistent deformations, or slope-deflection method. These methods can be used to obtain additional equations needed to solve for the unknown forces in the truss members.
• The general approach to analyzing an indeterminate truss using the method of sections involves cutting the truss into smaller sections and solving for the unknown forces in the members of each section using the method of sections. The method is then combined with other methods to solve for the remaining unknown forces in the truss members.

In the force method of analysis:

In this method, the primary unknown forces in the members and compatibility equations are written for displacement and rotations (which are calculated by force-displacement equations).

In solving these equations, redundant forces are calculated. Once the redundant forces are calculated, the remaining reactions are evaluated by equilibrium equations.

In the displacement method of analysis:

Primary unknowns are the displacements and initially, force-displacement relations are computed and subsequently, equations are written satisfying the equilibrium conditions of the structure in this method. After determining the unknown displacements, the other forces are calculated satisfying the compatibility conditions and force-displacement relations.

Difference between Force & Displacement Methods

1. Method of consistent deformation 2. Theorem of least work 3. Column analogy method 4. Flexibility matrix method 5. Castigliano’s Theorem- II | Example:
2. Slope deflection method 2. Moment distribution method 3. Kani’s method 4. Stiffness matrix method 5. Castigliano’s Theorem- I |

In a simply supported singly reinforced concrete beam, the reinforcement is placed below the neutral axis of the beam.

It is due to the fact that concrete is weak in tension, and the portion below the neutral axis is in tension. In order to bear these tension stresses the reinforcement is placed below the neutral axis.

Explanation: 

Construction joints in Cement concrete work occur where two successive placement of concrete meet. These joints are placed at the end of days work. They may be design to permit movement or load transfer.

Construction joints in cement concrete work is provided at the location where bending moment and shear force is minimum and should not be provided at the corner.

A large area cannot be concreted within a day. it will take a long time and a huge volume of concrete could be required. Therefore, as per the capacity of the batching plants and the contractor's human resource, the size of the pours could be selected, so the joint form between previous concreting and a fresh concreting called construction joint.

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Explanation: 

Water Cement Ratio: 

• The water-cement ratio of the fresh concrete mix is important factors determining the quality and properties of hardened concrete, as it directly affects the concrete porosity, and a good concrete is always a concrete as compact and as dense as possible.
• A good concrete must be therefore prepared with as little water as possible, but with enough water to hydrate the cement minerals and to properly handle it.
• Water–cement ratios in the range of 0.40 to 0.60 are typically used. For higher-strength concrete, lower w/c ratios are necessary, along with a plasticizer to increase flowability.
• Water Cement ratio is expressed in Litres of water required per kg of cement.

Explanation:

Cement

• Cement is important for construction activities like building houses, factories, bridges, roads, airports, dams, and for other commercial establishments.
• This industry requires bulky and heavy raw materials like limestone, silica, alumina, and gypsum.
• Coal and electrical power are needed for production and rail for transportation.
• When cement is mixed with water, it becomes hard over a period of time. This is called the setting of cement.
• Gypsum is usually added to cement to prevent early hardening or “flash setting”, allowing extended working time.

Cement basically constitutes of calcareous and argillaceous materials.

Raw material ingredients used for manufacturing of Portland Cement are:

Calcareous Materials: Calcareous Materials are compounds of calcium and magnesium. Limestones are common calcareous material used in manufacturing cement. Chalk and shells are also used as calcareous material.

Argillaceous Materials: Argillaceous Materials are mainly silica, alumina and oxides of iron. Clay and shale are common argillaceous material used as cement ingredient in the process of manufacturing cement.

Explanation:

The different components used in the pitched roof are:

Purlins:

They are horizontal wooden or steel members that are used to support the common rafters of a sloping route when the span is larger.

Eaves:

The bottom edge of the sloped roof surface is called the eaves from which rainwater drops down during rain. 

Gable: 

The triangular upper part of a wall formed at the end of a pitched roof is called a gable.

Rise of truss: 

The vertical distance between the wall plate and the top of the ridge is known as rising.

Hip:

It is a place where two sloping surfaces meet, where the exterior angle is more than 180°.

Span:

The horizontal distance between the internal faces of walls or supports is called a span.

​Verge:

The edge of a gable running between the eaves and ridge is called a verge.

Pitch: 

The inclination of the sides of a roof to the horizontal plane is called pitch.

Ridge:

The apex of the angle is developed at the top by the inclined surfaces at the top of the slope. 

Rafters:

It runs from the ridge or hip of the roof to the wall plate of the external wall.

Explanation:

Soil stabilization:

Soil stabilization aims at improving soil strength and increasing resistance to softening by water by bonding the soil particles together, waterproofing the particles, or a combination of the two.

Soil Stabilization is either achieved by Mechanical, Physical, Chemical or Physio chemical Stabilization.

Physical stabilization may be achieved by the addition of:

1. Cement stabilisation
2. Lime stabilisation
3. Bitumen stabilisation
4. Chemical stabilization
5. Resin stabilisation

Chemical stabilization may be achieved by the addition of:

1. Calcium Chloride
2. Sodium Chloride
3. Sodium Silicate
4. Polymers
5. Chrome Lignin
6. Other Chemicals, etc.