The document discusses the general requirements of IS:456-2000 including defining limit states, characteristic and design strengths of concrete and steel, and design loads. It also addresses mix proportions for different grades of concrete and factors to consider for partial safety of loads such as error in assessment and possible overloading.

1. STRUCTURAL DESIGN - I
GENERAL REQUIREMENTS OF IS:456-2000
LECTURE - 1
MADE BY:
Kavita Singh
Assistant Professor
ITM Vocational University, Vadodara
kavitas@itmvu.in; 9998935324

2. Q.1: What do you mean by “Limit State”?
aNS: aS per IS:456-2000, page No. 67:
The acceptable limit for the safety and serviceability requirements
before failure occurs is called Limit State.
Q.2: Define Characteristics Strength.
aNS: aS per IS: 456-2000, page No.67:
It means that value of strength of the material below which not
more than 5% of the tests results are expected to fall.

3. Q.3: Define Characteristic Load.
aNS: aS per IS: 456 - 2000, page No. 67:
It means that value of load which has a 95 % probability of not
being exceeded during the life of the structure.
Q.4: What is the Design strength of Concrete?
aNS: aS per IS: 456-2000, page No.68:

Fck
FactorSafetyPartial
ConcreteofstrengthsticCharacteri
concreteofstrengthDesign 

4. Q.5: What is the Design Strength of Steel?
aNS: aS per IS: 456-2000, page No. 68:
Q.6: Write down the formula for Design Load.
aNS: aS per IS: 456-2000, p.68:

Fy

FactorSafetyPartial
SteelofStrengthsticCharacteri
SteelforStrengthDesign

F
FdLoadDesign 

5. Q.7: As per IS:456-2000, write down the partial safety factor for
concrete and steel.
aNS: aS per IS:456-2000, page No. 68:
Partial Safety Factor for Concrete = 1.5
Partial Safety Factor for Steel = 1.15
Q.8: Which grade of concrete is used for PCC work?
aNS: M 15 or lower grade of concretes are used for the PCC
work.

6. Q.9: Write down the mix proportions for the different grades of
concrete.
aNS: M 5 = 1:5:10
M 7.5 = 1:4:8
M 10 = 1:3:6
M 15 = 1:2:4
M 20 = 1:1.5:3
M 25 = 1:1:2

7. Q.10: What to consider partial safety factor for loads?
aNS: (a) Error in load assessment.
(b) Possible Overloading.
(c) Load Combination.
(d) Repeated Loading.
(e) Modification in Loads.