Design of Reinforced Concrete Structure (IS 456:2000)

Design of Reinforced Concrete
Structure
(IS 456 :2000)
For Full Course visit,…
www.machenlink.com

RCC Design of Different Type of
Structural Elements
Beam
Column
Slab

RCC  Topics are taught thoroughly and systematically to clarify the basic
concepts and fundamental principles without weakening technical hardship.
 Many example problems are solved to demonstrate or to provide further
insights into the basic concepts and applications of fundamental principles.
 The solution of each example is preceded by a strategy, which is intended
to teach students to think about possible solutions to a problem before they
begin to solve it.
 Each solution provides a step-by-step procedure to guide the student in
problem-solving which really help students for university examinations and
for the conventional exam like ESE (Engineering Services Examinations).
Some Key Features of this Course

Design of Reinforced Concrete Structure (IS 456:2000)
01 || Introduction ||
02 || Analysis and Design of Beam || WSM ||
03 || Analysis and Design of Beam || LSM ||
04 || Design for Shear, Torsion and Bond ||
05 || Design for Slabs ||
06 || Design for Compression Members ||
For Full Course visit,…
www.machenlink.com

RCC What is “IS 456:2000” ?
 IS 456: 2000 is Indian National Building Code.
 Provide guidelines for the design and construction of structures.
 Evolved from the collective wisdom of expert structural engineers.
 Periodically revised to bring them in line with current research, and often, current trends.
01 || Introduction to RCC

Objective of Structural Design

compressionTension

IS 456 - 2000
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
Disaster Management of India
 2600People die every year due
to building collapse.

2013
7 storey Building collapsed in
Thane , Maharashtra
Use of sub-standard
construction Material.
Reason of Failure

IS 456 - 2000
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
.. .. .. .. … ..
1. Strength
Stresses should not exceed
the critical values.

Ultadenga flyover in Kolkata
40m Curve

2. Stability
 Overturning
 Buckling
 Sliding
should be prevented.

3. Serviceability
 Stiffness
 Deflection
 Impermeability
 Durability

2.
Stability
1.
3.
Strength
Serviceability

Planning phase
Structural Analysis And Design
Are the safety &
Serviceability
Requirement
Satisfied?
Construction Phase
YES
NO
Revised
Structural
Design
Structural Analysis And Design:
 Selection of most appropriate
Structural System to bring the architect
concept into being
 Estimation of loads on structure
 Structural analysis for estimation of
stresses.
 Structural Design of actual
proportion( size, reinforcement etc.)
for safety and serviceability.
 Submission of drawing.
Reinforced Concrete Construction
Planning Phase:
 Carried out by Architect/planner to
plan the layout of structure
 Functional Requirement
 Aesthetics Requirement
 Budgetary Requirements

Concrete & Reinforced Steel
Plain Concrete is made by mixing of :
 Cement
 Aggregate
 Water
 Admixture
 Concrete is generally prepared at the site itself,
although ready-mixed concrete and precast
concrete are also used.
 Concrete tensile strength is very low
(negligible) compare to its compressive
strength.
 Concrete compressive strength is very high.

Hairline Crack
(not Perceptible )
Steel Bars Undergo
Yielding
Steel Bars embedded
Ductile mode of failure under heavy load.
Concrete & Reinforced Steel
Steel embedded in concrete called
reinforced steel
 Usually manufactured in factories
under control conditions.
 It can effectively take up the tension
that induced due to –
 flexural tension
 direct tension
 diagonal tension
 environmental effect
 Steel also impart ductility to materials
 Steel compressive strength is
more than concrete.
= RCC

Grade of Concrete
Design properties of concrete are:
This is measured by standard test on concrete cube.
150 mm Cube
M 20
M refers to mix Characteristics compressive strength (28
Days) expressed in MPa (N/mm2 )

Grade of Concrete
Design properties of concrete are:
150 mm Cube
Types of concrete Grade
High Strength concrete Above M 60
Standard Strength concrete M25 to M 55
Normal Strength concrete M 10 to M20
IS 456 -2000 TABLE NO. 02
This is measured by standard test on concrete cube.

≠ ≠
Characteristic Strength ( fck )
Even we collect them from same mix but there
Compressive strength is not same.

Definition: Its is defined as the strength of material below which not more
than 5% result are expected to fall.
Specimen
Compressive strength (28 days)5% Area
 Subjected to considerable variation in
strength.
 The variation in concrete is expressed in
terms of standard deviation and/or
coefficient of variation.
Target mean strength fm = fck + 1.65s
Characteristic
strength
1.65𝜎
Mean
strength
Coefficient of variation =
𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑑𝑎𝑣𝑖𝑎𝑡𝑖𝑜𝑛
𝑚𝑒𝑎𝑛 𝑠𝑡𝑟𝑒𝑛𝑔𝑡ℎ

Definition: Its is defined as the strength of material below which not more
than 5% result are expected to fall.
Values of standard deviation ( 𝜎 ) as per IS 456-2000
Grade M 10, M 15 M 20, M25 ≥ M 30
𝜎 (N/𝑚𝑚2) 3.5 4.0 5.0

Modulus of Elasticity of Concrete (𝑬 𝒄)
Concrete - Brittle material.
 Non-elastic
 Non-linear
Only initial portion of
curve is linear.
𝑬 𝒄 =
𝑆𝑡𝑟𝑒𝑠𝑠
𝑠𝑡𝑟𝑎𝑖𝑛
1. Short-term elastic strain
Strain
Stress
2. Long-term elastic strain
𝑬 𝒄 = short-term modulus
of elasticity
𝑬 𝒄𝒆 = effective modulus
of elasticity
(Instantaneous load) (creep & shrinkage)

Modulus of Elasticity of Concrete (𝑬 𝒄)
Possible type of 𝑬 𝒄 (Short-term strain)
 Initial Tangent Modulus (ITM)
 Tangent Modulus (TM)
 Secant modulus (SM)
IT
T
S
Strain
Stress
Specified
stress level
 Empirical formula for static modulus
given by IS 456-2000 (Cl. 6.2.3.1)
𝑬 𝒄 = 5000 fc𝒌
Based on ITM

Tensile Strength
7 to 15% of compressive strength.
Tensile strength tests.
 Direct tension test
 Splitting test
 Flexural Tension test.
Secondary stresses
induced due to
gripping
Direct tension test

Tensile Strength
 Splitting test
Splitting Test

Tensile Strength
 Splitting test
Supporting pin
Loading pin
Three Point Method
100mm x 100mm x 500mm

Tensile Strength
Modulus of Rupture (fcr )
The theoretical maximum tensile stress
reached in extreme fiber.
Empirical Formula suggested by Code
fcr = 0.7 fc𝒌
Relation between tensile &
compressive stress.
M
Z
=fcr

Creep (𝜽)
Instantaneous
strain
Creep
strain
Ultimate creep
strain
Totalstrain
Time (t)
Time dependent component of total
strain
Instantaneous
strain
Creep
strain
Creep coefficient:
𝜽 =
𝐶𝑟𝑒𝑒𝑝 𝑠𝑡𝑟𝑎𝑖𝑛 𝑎𝑡 𝑡𝑖𝑚𝑒 (𝑡)
𝑖𝑛𝑠𝑡𝑎𝑛𝑡𝑎𝑛𝑒𝑜𝑢𝑠 𝑠𝑡𝑟𝑎𝑖𝑛
Both depend on Stress level.

Creep (𝜽)
Creep Coefficient for design:
IS 456-2000 (Cl. 6.2.5.1)
Days 𝜽
7 2.2
28 1.6
1 year 1.1
Effective modulus of Elasticity (𝑬 𝒄𝒆)
Or long-term modulus
𝑬 𝒄𝒆 =
𝑬 𝒄
1+𝜽
Instantaneous
strain
Creep
strain
Ultimate creep
strain
Totalstrain
Time (t)
Instantaneous
recovery
Creep
recovery
Residual creep
strain
unloading

Shrinkage
Concrete shrinks ( hardened state )
Due to loss of moisture by Evaporation.
Similar to Creep – induced time dependent strain. Unlike Creep – independent of Stress level
Dry Shrinkage:– reduction in volume of concrete.
Shrinkage Restrain developed tensile stress – lead to cracking
Differential Shrinkage: due to moisture or thermal gradient,
OR due to unsymmetrically placed reinforced steel in beam
 Induced internal stresses
 Curvature
 Deflection
Shrinkage strain for Design:
Expressed as linear strain (mm/mm)
IS 456-2000 (Cl. 6.2.4.1)
0.0003 mm/mm

Durability
Effective way to Increase durability:
 Provide adequate clear cover to embedded steel.
 Using coated steel
 Using appropriate minimum grade of concrete according to
environmental exposure condition.
Nominal or clear cover
What is durability of concrete ?
concrete is to serve the purpose for which it is designed during its intended lifetime.
Some factors which effect the durability of concrete.
Internal factors External factors
 Environmental
effects
 Properties of
ingredient used to
make concrete
 Alkali-reactive aggregate
 Salty water

Durability
Exposure
category
Description
Min.
Grade
Min.
Cover
(mm)
Min.
Cement
Kg/𝒎 𝟑
)
Max.
Free w/c
content
Mild Protected against weather or aggressive conditions, except if located in
in coastal area
M 20 20 300 0.55
Moderate Sheltered from severe rain or freezing whilst wet, or Exposed to
condensation & rain, or continuously under water, or in contact with or
buried under non-aggressive soil or ground water, or sheltered from
saturated ‘salt air’ in coastal area
M 25 30 300 0.50
Severe Exposed to severe rain, alternate wetting and drying or occasional
freezing whilst wet or severe condensation, or completely immersed in
sea water, or exposed to coastal area
M 30 45 320 0.45
Very severe Exposed sea water spray, corrosive fumes or severe freezing whilst wet,
wet, or in contact with or buried under aggressive sub-soil or ground
water
M35 50 340 0.45
Extreme Members in tidal zone, or member in direct contact with liquid/solid
aggressive chemicals
M40 75 360 0.40
Cl. 8.2.2.1 – Environmental Exposure Conditions

Reinforced Steel
Size of Bars…
Rebars – Reinforcing Bars
Nominal diameters - 5 mm to 50 mm.
Mostly used between – 8 mm to 32 mm

Reinforced Steel
Size of Bars…
Rebars – Reinforcing Bars
Nominal diameters - 5 mm to 50 mm.
Plain Bars Deformed Bars
Smooth Surface Lugs on surface
Lugs
enhanced the
bond
between steel
and concrete

Reinforced Steel
Grade of Steel: Yield strength of steel
Cl. 36.1 – Specified yield strength may be treated as characteristic strength. (Expressed in N/mm2)
Types of steel:
 Mild steel (Fe 250): less commonly used because of
their low strength.
 Medium Tensile Steel
 Cold twisted Bar: HYSD ( High Yield Strength
Deformed ) Bars. e.g. Fe 415, 500
 TMT Bars: Thermo mechanically Treated(TMT)
inner core – soft and ductile
outer shell – very high tensile strength
Strain
Stress
Fe500
Fe415
Fe250
Modulus of elasticity (𝑬 𝑺):
For all grade – initial linear elastic portion with
constant slope
Cl. 5.6.3 specifies 𝑬 𝑺 = 2 x 105
𝑀𝑝𝑎
𝑬 𝑺 = 2 x 105
𝑀𝑝𝑎
Anti-corrosive coating
High strength
Ductile
𝑓𝑦

Yield Strength of HYSD Bars
Strain
Stress
𝐸𝑆
𝐸𝑆
𝑓𝑦
0.002 𝑓𝑦
𝐸𝑆
𝜀 𝑦 = 0.002 + 𝑓𝑦/𝐸𝑆
Yield stress is read at 0.2%
proof strain.
i.e. at strain of 0.002

Design of Reinforced Concrete Structure (IS 456:2000)

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Design of Reinforced Concrete Structure (IS 456:2000)

Similar to Design of Reinforced Concrete Structure (IS 456:2000) (20)

More from MachenLink

More from MachenLink (10)

Recently uploaded

Recently uploaded (20)

Design of Reinforced Concrete Structure (IS 456:2000)