Design of Structures

Understanding Load Calculations | Structural Design

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Load Calculations | Design of Buildings

In our earlier article, we discussed “Different types of loads” and their importance in Structural design.

Now we will move on with our further discussion on the following points:

  • Design principle assumption and notation assumed
  • Design Constant
  • Assumptions regarding Design
  • Loads on Beams
  • Loads on slabs

Design principle assumption and notation assumed:

The notations adopted throughout are same as given in IS:456:2000

Density of material used in accordance with reference to IS:857-1987s

Sr.no Material Density
1 Plain concrete 24 KN/m3
2 Reinforced cement concrete 25 KN/m3
3 Flooring material (cement mortar) 1.00 KN/m3
4 Brick masonry 19 KN/m3

Design constant

Using M20 and Fe415 grade of concrete and steel respectively for columns and footings

Therefore:

Fck – i. e. Characteristic strength for M15 – 15 N/mm2

Fck – i. e. Characteristic strength for M15 – 15 N/mm2

Fck – i. e. Characteristic strength for M20 – 20 N/mm2

Fy – i. e. Characteristic strength for steel – 415 N/mm2

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Causes of Foundation Damage and Retrofitting | Settlement in the ground

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Causes of Foundation damage and Retrofitting 

In one of my previous articles, we discussed various steps in which the survey of the foundation has to be done in order to be considered for retrofitting.

In this article, we will discuss various reasons or causes for the damage of the foundations.

Types of foundation damage can be classified as follows:

Erosion

  1. Natural rock
  2. Brick

Rot

Insects

Moisture damage

  1. Frost wedging
  2. Salt bloom

Settlement in the ground

  1. Groundwater lowering
  2. Limited bearing capacity of the ground (land)
  3. Uneven bedrock depth
  4. Excavations performed below the foundations and poor quality of backfill
  5. Increased load on the ground leading to failure
  6. Damage to the neighbouring houses
  7. Horizontal movement occurring in the ground

 Frost heave/adfreezing

Alum shale

Now we will move on with the discussion in detail on the types of foundation damage occurring due to Settlement in the ground.

Lowering in the Groundwater level

When the buildings are built on compressible soils, the resulting stress on the soil causes the soil to compress. Raft foundations are used in these kind of soils.

Since the soil undergoes compression the upper portion of wooden piles rot when groundwater level sinks.

There are various conditions which can cause the changes in the groundwater level or pore water pressure. They are as follows:

  • Ice Static Rebound
  • Dewatering (seen in cities)
  • Ditches and pipes below the groundwater level
  • Deep Foundations and Basements (causing further drainage of the ground
  • Tunnelling
  • By the removal of foundation sills
  • Construction of non-permeable surfaces such as roads, pathways causing the least amount of natural precipitation
  • Use of deciduous trees should be avoided in areas with low groundwater. They require a lot of water for their growth. They pull all the water that is available around them causing the lowering of groundwater.

Introduction to Design of RCC Structures

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RCC structures

RCC (Reinforced Cement Concrete) is a construction technology which evolved with the evolution of different structural materials in the 18th century during the Industrial Revolution.

Industrial Revolution brought in new technology which helped in the manufacture of various materials. The Architect Le Corbusier used RCC for various constructions. He believed that any shape and form was possible; if RCC is to be used.

For example, Notre Dame Du Haut, Ronchamp, France

This is an example of Le Corbusier Project where he used RCC like plastic.

Notre Dame Du Haut, Ronchamp, France | RCC Structures
Notre Dame Du Haut, Ronchamp, France | RCC Structures

What is RCC?

RCC means Reinforced Cement Concrete, i.e., cement concrete reinforced with steel bars, steel plates, steel mesh etc to increase the tension withstanding capacity of the structure.

Cement Concrete can take up immense compression but weak in tension whereas steel is good in withstanding both tension and compression.

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Methods of Structural Design | Design of Steel Structures

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Structural design is the science of studying the Mechanics of a structure. Designing the skeleton of a building determines the real strength of the structure.

If the structure is externally beautiful and internally weak, it results into dramatic structural failure.

Structural Framework in a building
Structural Framework in a building

In this article, we are going to discuss in detail about the “Various Methods of Structural Design”.

All parts of a structural steel framework of a structure shall be capable of sustaining the most adverse combination of dead loads, the prescribed super imposed roof and floor loads, wind loads, seismic forces where applicable, and any other forces or loads to which the building maybe reasonably subjected without exceeding the permissible stresses.

The following methods may be employed for existing steel framework:

  1. Simple design
  2. Semi-rigid design
  3. Fully rigid design
  4. Plastic design

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