Sanjer Bela Civil Engineering Site

What are the assumpions made in the theory of pure bending? The theory of pure bending relies on several key assumptions: the material is homogeneous and isotropic, the beam is initially straight, plane sections remain plane after bending, and the material obeys Hooke's law within the elastic limit.  Here's a more detailed breakdown of the assumptions : Homogeneous and Isotropic Material: The material of the beam is assumed to be uniform throughout (homogeneous) and have the same properties in all directions (isotropic).  Initial Straightness: The beam is considered to be initially straight before any bending occurs.  Plane Sections Remain Plane: Transverse sections of the beam that are plane before bending remain plane after bending.  Material Obeying Hooke's Law: The material is assumed to behave elastically and obey Hooke's law, meaning stress is directly proportional to strain within the elastic limit.  Modulus of Elasticity is the Same in Tension and Compre...

  Lateral Starin & Longitudinal Strain Laterial Strain Lateral strain, also known as transverse strain, is the deformation of a material in a direction perpendicular to the applied load, specifically the change in diameter or breadth divided by the original diameter or breadth. Here's a more detailed explanation: Definition: Lateral strain is the ratio of change in dimension (like diameter or breadth) to the original dimension, but in a direction perpendicular to the applied force (or stress). Relationship to Longitudinal Strain: When a material is subjected to a longitudinal stress (force applied along its length), it will typically extend in the direction of the stress and contract in the transverse or lateral direction. Poisson's Ratio: The ratio of lateral strain to longitudinal strain is called Poisson's ratio, which is a material property that describes how much a material deforms in one direction when stressed in another direction. Formula: La...

  what is torque and torsion? what is the difference between torque and torsion? The terms torque and torsion are related to rotational forces, but they describe different concepts: Torque : Torque refers to a force that causes an object to rotate around an axis or pivot point. It is the measure of the rotational force applied to an object. The formula for torque is: τ=F×r×sin⁡(θ)\tau = F \times r \times \sin(\theta)τ=F×r×sin(θ) where τ\tauτ is the torque, FFF is the force, rrr is the distance from the pivot point, and θ\thetaθ is the angle between the force vector and the lever arm. Torque is typically used in situations where a force is applied at a distance from a center of rotation (like turning a doorknob or the engine in a car). Torsion : Torsion refers to the twisting of an object due to an applied torque. It describes the stress and strain experienced by a material when it is subjected to ro...

  what is caisson? A caisson is a watertight structure that is used as a foundation for buildings and other structures. They are often used in areas with soft or water-saturated soil, or in coastal areas. Caissons are large, hollow cylinders that are made from concrete, steel, or wood.  How caissons are used  Caissons are sunk into the ground until they reach bedrock or stable soil. They are then filled with concrete to create a strong foundation. Caissons are used to support heavy loads. Types of caissons Pneumatic caissons: A watertight box or cylinder-like structure that is closed at the top and open at the bottom.  Box caissons: A box-shaped structure that is closed at the bottom and open at the top.  Monolithic caissons: The largest type of caisson, which are constructed within quay walls.  Benefits of caissons   Caissons are affordable solutions for underwater foundations. They are easy to build and clean. They can be altered according to the spe...

  what is drilled piers foundation & construction of Drilled piers  Drilled Piers Drilled piers, also known as drilled shafts or caissons, are deep foundation systems formed by excavating a cylindrical hole and filling it with reinforced concrete, used to transfer loads from unstable soil to deeper, stable ground. Here's a more detailed explanation: What they are: Drilled piers are a type of deep foundation solution that involves drilling a hole into the ground, placing reinforcing steel, and then pouring concrete to form a strong, vertical pier. How they work: They transfer the structural load from the upper, potentially unstable soil layers to a deeper, more stable soil or bedrock layer. When they are used: Unstable soil: They are particularly useful when the soil at the surface is weak or unstable, such as in areas with expansive soils or where there's a high risk of erosion. Heavy loads: They are well-suited for supporting heavy structures, bridges, and other infrast...

  12)  Mild steel bars in either direction in RCC slabs should not be less than -------- of total cross-sectional area ans - 0.15 % Concept In RCC slabs, mild steel reinforcement in either direction should not be less than 0.15% of the total cross-sectional area.  Here's a more detailed explanation:  Minimum Reinforcement: As per IS 456:2000, the minimum reinforcement in either direction of a slab using mild steel should not be less than 0.15% of the total cross-sectional area. HYSD Bars: If high-strength deformed bars (HYSD) are used, the minimum reinforcement in either direction should not be less than 0.12% of the total cross-sectional area. IS 456:2000: These guidelines are based on the Indian Standard code IS 456:2000, which provides detailed recommendations for the design and detailing of reinforced concrete structures.

  \  11) Diameter of steel reinforcing bars should not excced ………….mm for a 100 mm thick RCC slab. ans - 1/8th of the thickness of the slab   concept For a 100 mm thick RCC slab, the diameter of steel reinforcing bars should not exceed 12.5 mm (100/8).  Here's a more detailed explanation: IS 456:2000 Clause: According to IS 456:2000, the diameter of reinforcing bars in a slab should not exceed one-eighth of the total thickness of the slab.  Calculation: In this case, the slab thickness is 100 mm. Therefore, the maximum diameter of the reinforcing bars should be 100 mm / 8 = 12.5 mm.  Practical Considerations: While the theoretical limit is 12.5 mm, in practice, standard bar sizes are used. Common sizes for main reinforcement in slabs include 8 mm, 10 mm, and 12 mm.  Minimum Reinforcement: It's important to remember that there are also minimum reinforcement requirements in slabs, which vary based on the type of steel used (mild steel or high-strength de...

  10) Dead load for RCC structure design may be computed from the code  ....... ans- IS 875 Part 1 Concept:- The dead load for RCC structure design may be computed from the code IS 875 (Part 1) , which is titled "Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures – Part 1: Dead Loads – Unit Weights of Building Materials and Stored Materials." IS 875 (Part 1) provides the unit weights of various building materials, which are used to calculate the dead load of a structure. It covers materials such as concrete, masonry, steel, and other common construction materials.

  9)  For RCC slabs spanning in two directions, the ............. of the two spans should be used for calculating the span to effective depth ratios, as per the code IS-456. ans - the smaller span Concept:- As per IS-456:2000 (Indian Standard Code of Practice for Plain and Reinforced Concrete), for RCC slabs spanning in two directions, the smaller span of the two spans should be used for calculating the span-to-effective depth ratio (l/d). This is mentioned in Clause 23.2.3 of IS-456. The smaller span is considered to control the deflection, as deflection is generally governed by the shorter span in two-way spanning slabs.

  8)  As per the code IS-456, for deflection control, the basic value of span to effective depth ratio, for continuous spans up to 10 m, should not be greater than ans - 26

    7)  Wind load for RCC structure design may be computed from the code ans - IS 875 Part 3 Concept W i nd load for RCC structure design may be computed from the IS 875 (Part 3): 1987 , which is the Indian Standard for Design Loads (Other Than Earthquake) for Buildings and Structures - Part 3: Wind Loads . The code provides a detailed procedure to calculate wind load on buildings and structures based on factors such as: Basic wind speed for the location. Terrain category . Height of the building . Shape of the structure . Topography . The calculation involves determining the design wind speed and applying it to the structure using the formulas and parameters provided in the code, which include coefficients for external and internal pressures.

6) The unsupported length between end restraints, as per the code IS-456, should not exceed ............. times the least lateral dimension of a column. ans - 60 times Concept According to IS 456:2000, the unsupported length between end restraints of a column should not exceed 60 times the least lateral dimension.  Elaboration: Clause 25.3.1 of IS 456:2000 specifies that the unsupported length between end restraints of a column should not exceed 60 times its least lateral dimension.  The unsupported length is the clear distance between members that can provide lateral support to the column.  For a pin-ended column, it is the distance between the hinges. 

  5)For a 2 m long cantilever beam with 1% Fe415 re-bars, the ratio of span to effective depth is .… ans - 7 to 8  Concept For a cantilever beam with 1% Fe415 reinforcement as per IS 456:2000 , the span-to-effective depth ratio is governed by the maximum permissible ratio for cantilever beams, which is typically specified in the code. For cantilever beams, the ratio of the span to the effective depth is limited by IS 456:2000, Clause 23.2.2 . For cantilever beams with 1% reinforcement , the maximum span-to-effective depth ratio is typically taken as 7 for cantilever beams. Thus, for a cantilever beam of length 2 meters , the span-to-effective depth ratio ( l / d l/d l / d ) would be: Span Effective Depth = 7 \frac{\text{Span}}{\text{Effective Depth}} = 7 Effective Depth Span ​ = 7 So, the effective depth d d d for the beam would be: d = Span 7 = 2000   mm 7 = 285.71   mm d = \frac{\text{Span}}{7} = \frac{2000 \, \text{mm}}{7} = 285.71 \, \text{mm} d = 7 Span...

  4) A square-shaped RCC solid slab, supported only on two opposite edges and unsupported on the remaining two edges, may be considered as .............- way slab. ans- One Way Slab Concept A square-shaped RCC solid slab, supported only on two opposite edges and unsupported on the remaining two edges, may be considered as a one-way slab . This is because, in such a configuration, the slab will primarily transfer loads in one direction (the direction of the two supported edges), and the other two edges (unsupported) do not significantly affect the load transfer. Hence, the slab behaves like a one-way slab.

   3)All RCC columns, as per the code IS-456, shall be designed for minimum eccentricity, equal to the unsupported length of column/500 plus lateral dimension/30, subjected to a minimum eccentricity value of .................... mm.  ans - 20 mm Concept As per IS 456:2000 , for RCC columns, the minimum eccentricity to be considered in the design is given by the following formula: e min = l u 500 + d 30 e_{\text{min}} = \frac{l_{\text{u}}}{500} + \frac{d}{30} e min ​ = 500 l u ​ ​ + 30 d ​ Where: l u l_{\text{u}} l u ​ is the unsupported length of the column. d d d is the lateral dimension of the column (the smaller of the two dimensions). However, IS 456:2000 also specifies a minimum eccentricity value of 20 mm . This means that, regardless of the result from the above formula, the minimum eccentricity should not be less than 20 mm . Let me know if you'd like more details!

  2) HYSD bars in either direction in RCC slabs should not be less than -------- of total cross-sectional area. ans-0.12 %. Concept  According to IS 456:2000 , for reinforced concrete (RCC) slabs, the minimum percentage of reinforcement using HYSD (High Yield Strength Deformed) bars in either direction should not be less than 0.15% of the total cross-sectional area of the slab. This requirement ensures that the slab has sufficient reinforcement to carry the loads and control cracking, while also considering the use of high-strength steel like HYSD bars. Let me know if you'd like further clarification!

  1)  As per the code IS-456, for controlling the vertical deflection of continuous two-way slabs with Fe415 grade HYSD steel reinforcement bars, the maximum value of the span to overall depth ratio should be -------------  ans- 26 .

  v What Is Tunnel Boring Machine? ü A tunnel boring machine (TBM), also known as a "mole" or a "worm", is a machine used to excavate  tunnels . Tunnels are excavated through hard rock, wet or dry soil, or  sand , each of which requires specialized technology. ü   Tunnel boring machines are an alternative to  drilling and blasting  (D&B) methods and "hand mining". ü   TBMs limit the disturbance to the surrounding ground and produce a smooth tunnel wall. This reduces the cost of lining the tunnel, and is suitable for use in urban areas. TBMs are expensive to construct, and larger ones are challenging to transport. These fixed costs become less significant for longer tunnels. ü   TBM-bored tunnel cross-sections range from 1 to 17.6 meters (3.3 to 57.7 ft) to date. Narrower tunnels are typically bored using  trenchless construction  methods or  horizontal directional drilling  rather than TBMs. TBM tunn...

  Ø   Advantage of Metro Railways   o    Metro rails are a modern, efficient, and environmentally friendly way to travel around cities. They can improve quality of life, economic development, and social equity . ·         Benefits of metro rails:-   1)      Reduced traffic congestion: Fewer cars on the road means less congestion and faster travel times.   2)      Reduced pollution: Metro rails run on electricity, which reduces air and sound pollution.     3)      Energy efficiency: Metro trains use less energy per passenger than cars and buses.   4)      Land use efficiency: Elevated and underground metro systems free up land for other uses.     5)      Comfort and safety: Metro trains are comfortable and have safety features.   6)      ...

v   Pre Tensioning Vs Post Tensioning:-Pre-tensioning and post-tensioning are both methods of pre stressing concrete, which involves reinforcing concrete with steel tendons .   ü Pre tensioning vs post tensioning When tendons are tensioned before concretes    are poured is called pre tensioning. When tendons are tensioned after concretes are hardened is called post tensioning. It is good for precast construction . It is good for long span and high structural efficiency. Steel is mostly stay horizontal. Steel wires can be placed any desired profile. §   Work Function:- 1)      In pre tensioning steel tendons are stressed before concrete is poured around them.   2)      In post tensioning the steel tendons are inserted in void in cured concrete using jacks.the jacks are replaced with permanent anchorages .   o    Benef...