TYPES OF OBSOLENCES -BUILDING

WHAT IS OBSOLESCENCE:

 "Obsolescence is state where a Buidling is no longer wanted even though good condition."

these are following 4 types of obsolescence affecting real estate. 

1.Functional obsolescence

2.Economic obsolescence

3.Technological obsolescence

4.physical obsolescence

1.Functional obsolescence

" Sometimes Buidling no longer wanted because of its old planning and outdated designing doesn't meet present day requirements". 

Ex;

a) A chawal with common toilets blocks.

b) an old palace may be in good condition in it, but no one like to stay in it, however if these palaces are converted   into hotels, they find good demand 

c) A multi-story office building that doesn't have an elevator

 

2.Economic obsolescence

 "it is decline in property value due to external Factors like zoning changes, recession, Adverse traffic changes. Construction of public nuisance type like jails sewer treatment Plant etc near property".

Ex

a) A residential Building existing on a plot which is situated in commercial Zone area. Thus, HABU is not made.

b) Dilapidation / Deccay | deterioration of building leading to huge repair cost.

c)  if value of properties in particular area falls severely either due to bad neighborhood or due to migration of population to newly developed town centers having better amenities.

3.Technological obsolescence

" It Is decline in property value due to latest products/ technology/workmanship etc".

ex

a) Load Bearing Building | timber, structures are technologically obsoleted and people

prefer to Stay in RCC Building of thin walls.

b) a wooden window is being a replaced by aluminum window.

4.physical obsolescence

" This in the normal wear and tear of building .it gets escalated due to poor /deferred maintenance of building. degree of physical obsolescence depends on factors like manner of usages, environmental aspects like natural forces aspects, accidental aspects".

What is SLAB - its Function, Design and and Its Type - Detailed explanation

What is slab - Function, Design and and Its Type - Detailed explanation

Slab :

The horizontal load carrying member which covers the building top or each floor of a Building is called slab. Hence the slab may be roof slab or floor slab. The slab transmits the load of persons using it, the objects kept on it and its self weight to the walls beams

Functions of Slab :

1. Provide a flat surface
2. To support load
3. Sound, heat and fire insulator
4. Act as a divider (privacy) for the occupants
5. Upper slab became the ceiling for the storey below
6. Space between slab and ceiling can be used to place building facilities 

Design Considerations in Slab:

1. Locate position of wall to maximize the structural stiffness for lateral loads
2. Facilitates the rigidity to be located to the center of building
3. Its necessary to check the slab deflection for all load cases both for short and long term basis. In general, under full service load, Deflection (d) < L/250 or 40 mm whichever is smaller.
4. Its preferable to perform crack width calculations based on spacing of reinforcement.
5. Good detailing of reinforcement will Restrict the crack width to within acceptable tolerances as specified in the codes and Reduce future maintenance cost of the building
6. Take care of punching shear i.e use more steel or thickness of concrete where there is chance of punching shear in the concrete slab. To increase shear capacity at the edges of walls and columns embed shear studs or stirrup cages in the slab.
7. Check for lateral stability

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 Types of Slab

Classification of slab

Depending upon the nature of supports, the slabs are classified

1. Simply supported slab   2. Cantilever slab   3. Continuous slab

(i) Simply supported slab : Slab just rests on the supports without any fixity (Fig.a).

(ii) Cantilever slab : A cantilever slab is fixed at one end and free at the other end as

shown in the figure. So the main reinforcement is placed at the top and the distributors are

provided perpendicular to the main reinforcement. e.g. Sunshade (Fig. b)

(iii) Continuous slab : When the slab is supported by more than two supports, it is

known as continuous slab. It is supported by wall and beams. Main reinforcement is

provided at the bottom throughout and at the top at supports (Fig. c).

 

One way slab :

“According to IS 456:2000, The ratio of longer span(lx) to shorter span(ly) which is (Lx/Ly   ) greater than 2 is known as One way slab “

• A slab supported along  two sides

•  It has only one plane of bending. When the ratio of the length of a room to its breadth is greater than   2, the slab is designed as one way slab.

•    Most of the load is carried by the short span (i.e. the width of the span) and is transferred to two supports.

 

·       

R   Reinforcement details :   Main reinforcement of the one way slab is along the width of

the room (i.e. parallel to the plane of bending ) and the distributors are laid at right angles

to the main reinforcement.

 

Two way slab :

“The ratio of longer span(lx) to shorter span(ly) which is less than 2 is known as two way slab. Two way slabs are normally supported from four sides”

•       A slab supported along all the four sides.

•    It develops bending moment in two directions.

•      When the ratio of the length of the room to its breadth is less than 2, the slab is designed as two way slab.

•        The load from the slab is transferred on all the four supporting sides.

 

Ø  Reinforcement details :   Main reinforcement of the one way slab is along the width of

the room (i.e. parallel to the plane of bending ) and the distributors are laid at right angles

to the main reinforcement.

In case of two way slab main reinforcements are provided both along the length as

well as along the width of the room

 

 

50 Practical Knowledge Every Civil Engineer Should Know

50 Practical Knowledge for Civil Engineers, we are going to discuss 50+ Civil engineering Knowledge, which every civil engineer must have to know. In the daily work schedule, we civil engineers are facing many problems from lack of knowing very basic things. We are going to share with you those basic technical things in a bunch.

1.	What is the Height of a Single Storey Building?
Ans	3.15 m
2.	What is the volume of One bag cement?
Ans	0.347 Cum or 1.25 Cubic feet.
3.	What is the Weight of one bag cement?
Ans	50 Kg
4.	What is initial Setting time of Cement?
Ans	30 min
5.	Final Setting time of Cement for Ordinary Portland Cement is ?
Ans	10 hours
6.	What is the minimum nos of bar for a rectangular column?
Ans	4 Nos
7.	What is minimum nos of bar for circular column?
Ans	6 Nos
8.	What is the size of Concrete cube?
Ans	150 x 150 x 150 mm
9	How much layer needs to fill a concrete cube for testing?
Ans	3 layers
10	How much layer needs to fill a slump for slump test?
Ans	4 Layers

11.	What is the Validity of use of Cement?
Ans	It is 3 months from Manufacturing
12.	For which test Universal Testing Machine is used?
Ans	Compression test of Concrete and Tensile test of reinforcement.
13.	What is the minimum curing period for concrete?
Ans	In normal Weather, it is seven days. For Dry or Hot weather, it is 10 Days.
14.	What is Deflection?
Ans	Deflection means temporary displacement
15.	What is deformation?
Ans	Deformation is a permanent displacement.
16.	What Is the formula for tensile strength of concrete?
Ans	0.7 route fck
17.	Which grade of concrete are called Ordinary Concrete?
Ans	M10 to M20 concrete are ordinary concrete.
18.	Which grade of concrete are called Standard Concrete?
Ans	M25 to M35
19.	Which grade of concrete are called High Strength Concrete?
Ans	M60 to M80
20.	How much time required to mix concrete in a mixture machine?
Ans	Minimum 2-3 min needs to mix concrete in a mixture machine.

21.	Which dia meter of bar should be used for Chairs?
Ans	Minimum 12 mm dia bar.
22.	What is the Minimum Cover for Footing , Column, Slab and Beam?
Ans	Minimum cover should be: Footing-50 mm, Column-40 mm, Slab- 20 mm, Beam-25 mm
23.	What is the ratio of most used cement concrete M10, M15, M20, M25?
Ans	For M10-(1:3:6), M15-(1:2:4), M20-1:1.5:3, M25-(1:1:2) The ratio is like Cement: Sand: Aggregates.
24.	What is the minimum thickness of slab?
Ans	Minimum thickness of slab should be 125 mm
25.	How much water absorption is allowed for brick?
Ans	Not more than 20 %
26.	What is the minimum Diameter for dowels bar?
Ans	Minimum 12 mm dia bar.
27.	What is the minimum allowable PH value of water?
Ans	It is not less than 6.
28.	What is the lap length of bars for compression zone?
Ans	24 d
29.	What is the lap length of bar for M20 Grade Concrete?
Ans	For Column-45d, Beam-60d, Slabs -60d.
30.	What is the lap length of bars for Tension zone?
Ans	50d to 60 d, d=dia of bar.

31.	What is Segregation of Concrete? and why its caused?
Ans	The separation of sand, cement, aggregates in concrete is called Separation of Concrete. Its caused due to improper water cement ratio. Also caused for poured above 1.5 height.
32.	What is the storage procedure of Cement?
Ans	1. Always store cement in a dry place. 2. Provide a gap of 300 mm from walls. 3. Never place cement bag direct in the floor always provide a 200 mm minimum height from floor. 4. Never put more than 10 nos of bag in a stack. 5. Keep in mind never make a cement storage near chemically effected floor or area and moisture effective area.
33.	Calculations for no of stirrup in a abeam?
Ans	Clear Span/ c/c Spacing+1
34.	What is TMT?
Ans	Thermomechanical Treated Bar.
35.	What is TMX?
Ans	Thermax Powered Bar.
36.	What is SD?
Ans	Super Ductile Bars.
37.	What is HYSD?
Ans	High Yield Strength Deformed Bars.
38.	What is CTD?
Ans	Cold Twisted Deformed Bar.
39.	What is the angle of staircase flight?
Ans	It is between 25 degree to 40 degree.
40	What is the minimum and maximum height of riser for residential building?
Ans	150 mm to 200 mm

41.	What is the minimum and maximum width of tread for residential building?
Ans	250 mm to 300 mm
42.	What is the minimum Hook length for bars?
Ans	It is 9D. (D-is dia of bar)
43.	How much bricks needs for 1 Cum Brick of 230 mm brick wall /work?
Ans	496 Nos
44.	How much bricks need for 115 mm thk brick work?
Ans	56 nos / Sqm
45.	What is Bleeding in Concrete?
Ans	When water comes out from a just made concrete or fresh concrete then it is called bleeding of concrete
46.	What is the maximum free fall for concrete?
Ans	Maximum allowable height of concrete free fall is 1.5 m.
47.	What is the Angle of hook in stirrups?
Ans	135 degree.
48.	How much bars should be lapped in a bar bending zone?
Ans	Not more than 50%
49.	What is the volume of one bag cement?
Ans	0.0347 cum or 1.23 CFT
50.	Calculations for weight of steel bars?
Ans	(D^2 xL)/162

Basic Knowledge of Every Civil Engineer

CONCRETE GRADES:
M5 = 1:5:10

M7.5=1:4:8
M10= 1:3:6
M15= 1:2:4
M20= 1:1.5:3
M25= 1:1:2

CLEAR COVER TO MAIN REINFORCEMENT:
1.FOOTINGS : 50 mm
2.RAFT FOUNDATION.TOP : 50 mm
3.RAFT FOUNDATION.BOTTOM/SIDES : 75 mm
4.STRAP BEAM : 50 mm
5.GRADE SLAB : 20 mm
6.COLUMN : 40 mm
7.SHEAR WALL : 25 mm
8.BEAMS : 25 mm
9.SLABS : 15 mm
10.FLAT SLAB : 20 mm
11.STAIRCASE : 15 mm
12.RET. WALL : 20/ 25 mm on earth
13.WATER RETAINING STRUCTURES : 20/30 mm

WEIGHT OF ROD PER METER LENGTH:
DIA WEIGHT PER METER
6mm = 0.222Kg
8mm = 0.395 Kg
10mm = 0.616 Kg
12mm = 0.888 Kg
16mm = 1.578 Kg
20mm = 2.466 Kg
25mm = 3.853 Kg
32mm = 6.313 Kg
40mm = 9.865 Kg

1bag cement-50kg
1feet-0.3048m
1m-3.28ft
1sq.m-10.76sq.f t
1cu.m-35.31cu.ft
1acre-43560sq.ft
1hectare-2.47acre

DESIGN MIX:
M10 ( 1 : 3.92 : 5.62)
Cement : 210 Kg/ M 3
20 mm Jelly : 708 Kg/ M 3
12.5 mm Jelly : 472 Kg/ M 3
River sand : 823 Kg/ M 3
Total water : 185 Kg/ M 3
Fresh concrete density: 2398 Kg/M 3

M20 ( 1 : 2.48 : 3.55)
Cement : 320 Kg/ M 3
20 mm Jelly : 683 Kg/ M 3
12.5 mm Jelly : 455 Kg/ M 3
River sand : 794 Kg/ M 3
Total water : 176 Kg/ M 3
Admixture : 0.7%
Fresh concrete density: 2430 Kg/ M 3

M25 ( 1 : 2.28 : 3.27)
Cement : 340 Kg/ M 3
20 mm Jelly : 667 Kg/ M 3
12.5 mm Jelly : 445 Kg/ M 3
River sand : 775 Kg/ M 3
Total water : 185 Kg/ M 3
Admixture : 0.6%
Fresh concrete density: 2414 Kg/ M 3
Note: sand 775 + 2% moisture, Water185 -20.5 =
164 Liters,
Admixture = 0.5% is 100ml

M30 ( 1 : 2 : 2.87)
Cement : 380 Kg/ M 3
20 mm Jelly : 654 Kg/ M 3
12.5 mm Jelly : 436 Kg/ M 3
River sand : 760 Kg/ M 3
Total water : 187 Kg/ M 3
Admixture : 0.7%
Fresh concrete density: 2420 Kg/ M 3
Note: Sand = 760 Kg with 2% moisture
(170.80+15.20)

STANDARD CONVERSION FACTORS
INCH = 25.4 MILLIMETRE
FOOT = 0.3048 METRE
YARD = 0.9144 METRE
MILE = 1.6093 KILOMETER
ACRE = 0.4047 HECTARE
POUND = 0.4536 KILOGRAM
DEGREE FARENHEIT X 5/9 – 32 = DEGREE
CELSIUS
MILLIMETRE= 0.0394 INCH
METRE = 3.2808FOOT
METRE = 1.0936YARD

MATERIAL CALCULATION:
CEMENT IN BAGS
01. PCC 1:5:10 1440/5*0.45 129.60Kg 2.59
02. PCC 1:4:8(M 7.5) 1440/4*0.45 162.00Kg 3.24
03. PCC 1:2:4(M 15) 1440/2*0.45 324.00Kg 6.48
04. PCC 1:3:6(M 10) 1440/3*0.45 216.00Kg 4.32
05. RCC 1:2:4(M 15) 144/2*0.45 324.00Kg 6.48
06. RCC 1:1.5:3(M 20) 1440/1.5*0.45 32.00Kg 8.64
07. RCC 1:1:2(M 25) 370.00Kg 7.40
08. RCC M 30 410.00Kg 8.20
09. RCC M35 445.00Kg 8.90
10. RCC M40 480.00Kg 9.60
11. Damp Proof Course CM 1:3,20mm tk 1440/3*0.022 10.56Kg 0.21
12. 2"tk precast slab M15 324*0.05 16.20Kg 0.32
13. 3"tk precast slab M15 324*0.075 24.30Kg 0.49
14. GC Masonry CM 1:7 1440/7*0.34 70.00Kg1.40
15. Brick Work CM 1:6 1440/6*0.25 60.00Kg 1.20
16. Brick Work CM 1:4, 115tk 1440/4*0.25*0.115 10.35Kg 0.21
17. Grano Flooring CC 1:1.5:3 1440/1.5*0.45*0.05 21.60Kg 0.43
18. Plastering CM 1:3, 12mm tk 1440/3*0.014 6.72Kg 0.13
19. Wall Plastering CM 1:4, 12mm tk 1440/4*0.014 5.00Kg 0.10
20. Laying Pressed Tiles Over
a CM 1:4, 20mm tk 1440/4*0.022 7.92Kg 0.16

01. Any Concrete Work
(PCC, RCC) 0.45*35.315= 20.00
02. Damp Proof Course
CM `1:3, 20mm tk 1.00
03. 2"tk Precast slab M15 1.00
04. 3"tk Precast slab M15 1.50
05. SS Masonry in CM 1:7 15.00
06. Brick Work in CM 1:6 15.00
07. Brick Work in CM 1:4,115mm tk 2.00
08. Grano Flooring in CC 1:1.5:3 1.00
09. Plastering in CM 1:3, 12mm tk 1.00
10. Wall Plastering CM 1:4, 12mm tk 1.00
11. Laying Pressed Tiles over a CM 1:4, 20mm tk
1.00
12. Ceramic Tiles, Marble, Granite, Cuddapah slab
CM 1:4, 20mm tk 1.00

UNIT WEIGHT:
01. Concrete 25 kN/m3
02. Brick 19 kN/m3
03. Steel 7850 Kg/m3
04. Water 1000 Lt/m3
05. Cement 1440 Kg/m3
06. 1Gallon 3.78 Litres
07. Link 8" = 200mm
08. 1 Hectare 2.471 acr(10000m2)
09. 1 Acr 4046.82m2 = 100 cent

DEVELOPMENT LENGTH:
01. Compression 38d
02. Tension 47 & 60d
03. 1 Cent 435.60 Sft
04. 1 Meter 3.2808 ft
05. 1 M2 10.76 ft2
06. 1 Feet 0.3048m
07. 1 KN 100Kg
08. 1kN 1000N
09. 1 Ton 1000Kg = 10,000 N = 10 kN
10. 1 kG 9.81N

BRICK:
Weight = 3.17 - 3.80 Kg
Water absorption 12 to 15%
Compressive strength = 36Kn/cm2
230mm Wall/m3 = 460 Bricks + 20Cft Sand +
66Kg Cement

Diff Between Development length and Overlapping length

Diff Between development Length and Lapping lenth

Development length (Ld)

“ The embeded length in concrete is called development length”

The minimum length of steel bars necessary on either side of section to develope bond is called as development length "

formula for finding Ld from IS Code

As per IS 456-2000
Clause:26.2.1
For LSM
Development length= (0.87 fy Ø)/(4τbd)
Ø= nominal diameter of the bar, fy : grade of steel
τbd = design bond stress given in 2.6.2.1.1.

Note – For Hysd steel bars increase values by 60%

How Much Ld provided

beam and slab – 48d

Column – 60d

Overlapping length

“The lap of bar needed ti transfer stresses to onther bars

ie means the available size of steel bars in market is 12 meter , if we have maximum span in beam , column and slab etc then we have to use two bars . That is required suffiecient length for transfering of stresses from one bar to onther is called lapping length

lapping length

beams and slab- 60d

columns – 45d

Why Bent Up Bars are provided and Cutting Length of bent up bars

Why Bent Up Bars are Provided in Beam and Slab

“ It is economical of material .normally for fixed beams and slab postive moments (Sagging) momments are mid span and Negateive moments (Hogging) at the Supports

so Bottom Steel is required at mid span and top steel resist negative moment at support "

• To resist negative bending momemt ie Hoggin
• To resist shear forc which is greater at Supports
• To reduce risk of brittle failure of slab and column connection

How much Bent Up Provided

 

1- Continuous slab ­ L/5

2- For End Support ­L/7

Cutting Length of Bent up Bars

• Extra length = d/sin45-d= 0.42d for one bent up

• Extra Length of 2 bent up = 2x0.42d = 0.84d

• d= D – (top+bottom cover)

Important Points For Civil site Engineer

Basic Points

A)     Bricks

1)      Bricks should be soak in water for 1 hour and spary water before use.

2)      For masonary work – 1 part cement and 6parts sand.

3)      The bricks should be laid alternate header and stretcher pattern

For block only stretcher pattern

The vertical joints should be staaaered

4)      The joints in bricks bulky filled with morter of 10-12mm

5)      For half partition bricks wall or 100mm thik wall place 6mm diameter rebar in every 4^th course

6)      The masonary wall should not raise 1 m height in day.

7)      Masonary wall cured for 10 days.

B)     Aggregate

1)      The size between 4.75mm to 80mm are coarse aggregate

2)      The rougn and non glacy surface aggregate are considered best for construction

3)      Angular aggregate assure high compressive strength in concreate because of the inter locking the angular aggregate due to their hisher specific surface area .

4)      The aggregate should not absorb water more than 10% of their weight (after 24 hr)

5)      Flaky/ thin, elongate / long aggregate not more than 35% by weight of total quantity.

6)      For RCC works 20mm and down size of aggregates.

7)      For 20mm and 10mm the combined ratio is 60:40 or 70:30

Development length:

“The embedded length in concrete is called development length. The minimum length of steel bars necessary on either side od section to develop bond is called as development length.”

Note: for HYSB steel bars increase value for mild steel by 60%

Overlapping length:

The lap of bar needed to transfer the stressen to other bar. Lap length is provided for overlapping two rebars in order to salely transfer the load from one bar to another

1)      Beams and slabs: 60d

2)      Column                : 45d

Bend:

The anchorage value of bend shall be taken as for each 45degree bend, 4 times diameter of bar to maximum upto 10 diameter of bars

What is Foundation

What is Foundation in Construction? Purpose and the Functions of Foundations

What is a Foundation in Construction?

Foundation is the lowest part of the building or the civil structure that is in direct contact with the soil which transfers loads from the structure to the soil safely. Generally, the foundation can be classified into two, namely shallow foundation and deep foundation.

A shallow foundation transfers the load to a stratum present in a shallow depth. The deep foundation transfers the load to a deeper depth below the ground surface.

A tall building like a skyscraper or a building constructed on very weak soil requires deep foundation. If the constructed building has the plan to extend vertically in future, then a deep foundation must be suggested.

Fig.1.Building Foundation in Construction

To construct a foundation, trenches are dig deeper into the soil till a hard stratum is reached. To get stronger base foundation concrete is poured into this trench. These trenches are incorporated with reinforcement cage to increase the strength of the foundation.

The projected steel rods that are projected outwards act as the bones and must be connected with the substructure above. Once the foundation has been packed correctly the construction of the building can be started.

The construction of the foundation can be done with concrete, steel, stones, bricks etc. The material and the type of foundation selected for the desired structure depends on the design loads and the type of underlying soil.

The design of the foundation must incorporate different effects of construction on the environment. For example, the digging and piling works done for deep foundation may result in adverse disturbance to the nearby soil and structural foundation. These can sometimes cause the settlement issues of the nearby structure.

Such effects have to be studied and taken care before undergoing such operations. Disposal of the waste material from the operations must be disposed properly. The construction of foundation has to be done to resist the external attack of harmful substances.

The foundation for each structure is designed such that:

• The underlying soil below the foundation structure does not undergo shear failure
• The settlement caused during the first service load or have to be within the limit
• Allowable bearing pressure can be defined as the pressure the soil can withstand without failure.

What is the Purpose of Foundation?

Foundations are provided for all load carrying structure for following purposes:

• Foundation are the main reason behind the stability of any structure. The stronger is the foundation, more stable is the structure.
• The proper design and construction of foundations provide a proper surface for the development of the substructure in a proper level and over a firm bed.
• Specially designed foundation helps in avoiding the lateral movements of the supporting material.
• A proper foundation distributes load on to the surface of the bed uniformly. This uniform transfer helps in avoiding unequal settlement of the building. Differential settlement is an undesirable building effect.
• The foundation serves the purpose of completely distributing the load from the structure over a large base area and then to the soil underneath. This load transferred to the soil should be within the allowable bearing capacity of the soil.

Functions of Foundation in Construction

Based on the purposes of foundation in construction, the main functions of the foundation can be enlisted as below:

1. Provide overall lateral stability for the structure
2. Foundation serve the function of providing a level surface for the construction of substructure
3. Load Distribution is carried out evenly
4. The load intensity is reduced to be within the safe bearing capacity of the soil
5. The soil movement effect is resisted and prevented
6. Scouring and the undermining issues are solved by the construction of foundation

Requirements of a Good Foundation

The design and the construction of a well-performing foundation must possess some basic requirements that must not be ignored. They are:

1. The design and the construction of the foundation is done such that it can sustain as well as transmit the dead and the imposed loads to the soil. This transfer has to be carried out without resulting in any form of settlement that can result in any form of stability issues for the structure.
2. Differential settlements can be avoided by having a rigid base for the foundation. These issues are more pronounced in areas where the superimposed loads are not uniform in nature.
3. Based on the soil and area it is recommended to have a deeper foundation so that it can guard any form of damage or distress. These are mainly caused due to the problem of shrinkage and swelling because of temperature changes.
4. The location of the foundation chosen must be an area that is not affected or influenced by future works or factors.