COMPRESSIVE STRENGTH TEST ON BRICKS

           The Compressive strength test on bricks is done in a lab and requires a specific equipment to conduct the test.

What is compressive strength of a material?

          Compressive strength is the load carrying capacity of a material. For any material there is some load carrying capacity upto some extent, once this limit is reached the material starts failing.

Compressive strength of Bricks:

          The ability of a material to resist failure in the form of crack or fissure is called Compressive strength. Compressive strength of bricks is the capacity of brick to withstand compression when tested in Compressive Testing Machine (CTM).

          In this test the brick is placed in between the jaws of the machine, and compressive force is applied on both faces of the brick and the compressive loads on the brick is increased step by step and the maximum load at which the crack is observed on the brick is noted.

Classification of brics based on compressive strength:

According to IS: 1077-1992, based on compressive strength of brick, Bricks are classified into 11 types. They are

Bricks Class Designation	Average Compressive Strength not less than
	(N/mm2)	(Kgf/cm2)
35	35	35
30	30.0	300
25	25.0	250
20	20.0	200
17.5	17.5	175
15	15.0	150
12.5	12.5	125
10	10.0	100
7.5	7.5	75
5	5.0	50
3.5	3.5	35

Based on compressive strength Bricks also classified as 

1. First class bricks    (Compressive strength = 10 N/mm²)

2. Second class bricks    (Compressive strength = 7 N/mm²)

3. Building bricks    (Compressive strength = 3.5 N/mm²)

4. Sundried bricks   (Compressive strength = 1.5 N/mm²/ to 2.5 N/mm² )

Reference: IS: 1077-1992  Common burnt clay Bricks Specification Read & Download

PROBLEM 1.1

          A rod 300 cm long and of diameter 4.0 cm is subjected to an axial pull of 20 KN. If the modulus of Elasticity of the material of the rod is 4.0 x 10⁵ N/mm²; Determine:

(i) The Stress, 

(ii) The Strain, and 

(iii) The Elongation of the rod.

Sol:

Given,  Length of the rod, L = 300 cm,

              Diameter,               D = 4.0 cm = 40 mm, 

              Area,                       A = (π/4) D² = (π/4) 40²  = 400 π mm²

              ^{Axial pull,              P = 20 KN = 20,000 N}

             Modulus of Elasticity, E  = 4.0 x 10⁵ N/mm²

(i) The Stress (σ) is given by equation as

                         σ = P/A = 20,000/400 π  = 15.92 N/mm² 

                 

(ii) Using the equation, the strain is obtained as 

                         E = σ/e

Strain              e = σ/E = 15.92 / 4.0 x 10⁵ = 0.0000398

(iii) Elongation is obtained by using equation as

                          e = dL/L

Elongation,     dL = e x L  = 0.0000398 x 300 = 0.01194 cm

                   

              

Credits: Books.google.co.in

                Scribd.com

RELATION BETWEEN STRESS AND STRAIN

FOR ONE-DIMENSIONAL STRESS SYSTEM:

          The relationship between stress and strain for one directional stress (i.e., Normal stress in one direction only) is given by Hook's Law. This law states that when a material is loaded within elastic limit, the developed normal stress is proportional to the strain produced. This means that the ratio of the normal stress to the corresponding strain is a constant within the elastic limit. This constant is represented by ‘E’ and is known as Modulus of Elasticity or Young’s modulus of Elasticity.

FOR TWO-DIMENSIONAL STRESS SYSTEM:

          Before going to learn about Two dimensional stress system, we have to know about Longitudinal strain, Lateral strain and Poison's ratio. 
1. Longitudinal Strain:
          When a body is subjected to an axial tensile load, then there is an increase in length of the body. But at the same time there is a decrease in other dimensions of the body at right angles to the line of action of the load applied. Thus the body having axial deformation and also deformation at right angles to the line of action of the applied load (i.e., Lateral deformation).
          The ratio of axial deformation to the original length of the body is known as Longitudinal strain (Linear). The Longitudinal strain is also defined as the deformation of the body per unit length in the direction of applied load.    
2. Lateral Strain:
          The strain which is produced right angles to the direction of applied load is known as Lateral strain.   

          Let us take an example, A rectangular bar of length 'L', breadth 'B' and depth 'D' is subjected to an axial tensile load 'P' as shown in below fig., . The length of the bar will increase while applying load, the breadth and the depth will decrease.

Let     δl = Increase in length
          δb = Decrease in breadth and, 
          δd = Decrease in depth.

Then Longitudinal strain = 
and Lateral strain =

Note: 
1. If longitudinal stain is tensile, the lateral strain will be compressive, vice-versa,
2. Hence for every longitudinal strain in the direction of the load applied is accompanied by lateral strain of the opposite kind in all directions perpendicular to the load.

3. Poisson's Ratio:
          When the material is subjected to stress within the elastic limit, The ratio of lateral strain to longitudinal strain is a constant. This ratio is called Poisson's ratio and it is denoted by a symbol 'μ' (MU).

Mathematically, 

as lateral strain is opposite in sign to longitudinal strain, hence algebraically, lateral strain is written as,  

4. Relation between Stress and Strain:
          Consider a two dimensional figure ABCD, subjected to two mutually perpendicular stresses 


Credits: books.google.co.in

                scribd.com

URBAN LOCAL BODIES

Overview of Urban Local Bodies:

          Municipal governance in India has existed since 1687 with the formation of Madras Municipal Corporation, and then Calcutta and Bombay Municipal Corporation in 1726. In 1882 the viceroy of India Lord Ripon (Who is known as the Father of Local Self Government) passed a resolution of local self-government which laid the democratic forms of municipal governance in India.

          Urban Local Bodies (ULB's) in Andhra Pradesh are traditionally mandated to undertake certain basic functions like Water supply, Sewerage & Septage, Roads, Drains, Street Lighting, Parks and Burial Grounds. The Twelfth Schedule of Constitution (Article 243 W) provides an illustrative list of Eighteen functions, that may be entrusted to the municipalities.

          After the advent of constitution 74th Amendment Act (CAA), 1992, the functional domain of urban local bodies has been expanded to include development programs along with traditional civic functions.  Due to Globalization, Liberalization and more critically, the urban explosion has increased the volume of services to be delivered by the urban local bodies.

CATEGORIES OF ULB’S :

          In Andhra pradesh ULS’s are divided into Six grades based on Annual Income and Population.

Grade	Annual Income
Selection Grade	Rs. 8 crores and above
Special Grade	Rs. 6 crores to Rs. 8 crores
First Grade	Rs. 4 crores to Rs. 6 crores
Second Grade	Rs. 2 crores to Rs. 4 crores
Third Grade	Rs. 1 crore to Rs. 2 crores
Nagar Panchayats	Below Rs. 1 crore

Functions of Urban Local Bodies:

          As per the provisions of the Municipality Acts & Corporation Acts, the Urban Local Bodies are entrusted broadly with the following functions.

1) Public health, sanitation, conservancy and solid waste management.

2) Provision of water supply, drainage and sewerage.

3) Construction and maintenance of roads, drains, culverts and bridges.

4) Provision of street lighting.

5) Urban poverty alleviation programs.

6) Slum improvement and up gradation.

7) Provision of public parks and play grounds.

8) Construction and maintenance of public markets, slaughter houses.

9) Urban planning including town planning.

10) Regulation of land use and construction of buildings.

11) Maintenance of secondary and elementary schools.

12) Urban development programs.

13) Vital Statistics including Registration of Births and Deaths.

14) Maintenance of burial grounds.

Sections in Urban Local Bodies:

S.NO	Section	Broad functions
1.	Administration	To look after general administration, including school administration and council meetings.
2.	Revenue	To assess and collect various taxes and non-taxes and collection of rents from municipal properties.
3.	Accounts	To maintain accounts, prepare annual accounts, budget, and attend to audit of accounts.
4.	Public Health and Sanitation	To look after sanitation, public health and solid waste management including medical and maternity services.
5.	Engineering	To look after water supply and sewerage, public works like roads, drains, buildings, parks and play grounds, street lighting
6.	Town Planning	To regulate town planning activities including land uses, layouts, building constructions and encroachments.
7.	Urban Poverty Alleviation (UPA)	To look after urban poverty alleviation programs.

Credits: https://en.wikipedia.org/wiki/Municipal_governance_in_India

                cdma.ap.gov.in

Ward Energy Secretary -- Roles & Responsibilities

Role:-

◦ To assist the AEE / AE (Civil / Electrical) in Power supply and Street Lighting.

◦ He is store in-charge for O&M related materials for Street Lighting and Power Bore wells

 Responsibilities:-

} Maintenance of street lighting and power bore well motors.

} Electro-mechanical works of water supply in the ward

} Erection of new electrical poles

} Maintain diary for daily work done

} Any other duties entrusted by the higher authorities from time to time