Prestressed Concrete Structures Questions on “Philosophy of Limit State Design”.
1. The limit state design philosophy recognizes the need to provide ____________
a) Safe structures
b) Designed structures
c) Stressed structures
d) Curved structures
Answer: a
Clarification: The limit state design philosophy recognizes the need to provide safe and serveciable structures at on economic price and at the same time presents a clearer idea of margins of safely actually employed to cover uncertainity and ignorance of the function as well as the performance of structure in actual practice.
2. The limit state design proposals have been evolved from the provisions of various ____________
a) Structures
b) Codes
c) Plan
d) Foundations
Answer: b
Clarification: It is important to note that the limit state design proposals have been evolved from the provisions of various earlier codes and the resulting changes in design, being minimal, provides the designer a greater freedom of choice.
3. A successful design should not only satisfy requirements but also ensure ____________
a) Serviceability
b) Total cost
c) Critical period
d) Planning
Answer: a
Clarification: A successful design should not only satisfy the requirements of safety against total collapse of the structure due to various causes but also ensures that the serviceability of the structure is not impaired while resisting normal working loads.
4. The primary object of structural design is to obtain ____________
a) Structural plan
b) Structural solution
c) Structural design
d) Structural lane
Answer: b
Clarification: The primary object of structural design is to obtain a structural solution which can result in the result greater overall economy by providing the maximum assistance in satisfying all the other requirements of the structure.
5. The permissible or working stress method of design, by Morsh is also referred as ____________
a) Limit theory
b) State theory
c) Elastic theory
d) Stress theory
Answer: c
Clarification: In this method the permissible stresses in a concrete and steel are assumed to be a fraction of the specified strength of individual material and a constant modular ratio is assumed for all loading conditions with the elastic behavior of concrete and steel, the permissible or working stress method of design pioneered by the German professor Morsch is also sometimes referred as elastic theory of design.
6. The inadequacy of the working load design in predicting ultimate loads of structure was recognized after ____________
a) Second world war
b) Cold war
c) Red war
d) First world war
Answer: d
Clarification: The inadequacy of the working load design in predicting ultimate loads of a structure was recognized after the first world war the factor of safety applied to the consistent materials does not present a realistic picture of the degree of safety against the collapse of the composite materials such as reinforced concrete used in the structural component.
7. The structure designed by ultimate load method, although having a desirable margin of safety may not be safe at ____________
a) Serviceable
b) Durable
c) Ductile
d) Tension
Answer: a
Clarification: A structure designed solely by the ultimate load method, although having a desirable margin of safety against collapse, may not be serviceable due to excessive deflections or development of objectionable cracks at service loads, this type of distress is particularly noticeable in structures designed by ultimate load methods using high strength materials.
8. The ultimate load design concepts extended to the design of continuous beams and frames is referred to as ____________
a) Working stress design
b) Permissible stress design
c) Limit state design
d) Collapse state design
Answer: c
Clarification: The ultimate load design have been extended to the design of continuous beams and frames where it is referred to as limit state design and this involves a redistribution of moments due to development of plastic hinges and an eventual collapse when the last critical hinge formed.
9. The philosophy of limit states is adopted and elaborated by ____________
a) European concrete committee(CEB)
b) European concrete committee(CEB)
c) European concrete committee(CEB)
d) European concrete committee(CEB)
Answer: a
Clarification: The philosophy of limit states was adopted and elaborated by the European concrete committee (CEB) to form the basis of the committee’s original publication in 1964and later in conjuction with the international federation for prestressing issued a complimentary report dealing with prestressed concrete in 1996.
10. The new philosophy of design termed the limit state approach was incorporated in which country code?
a) Europe
b) Russia
c) Canada
d) India
Answer: b
Clarification: A new philosophy of design, termed the limit state approach, which was incorporated in Russian code in 1954 basically the limit state design is a method of designing structures based on statistical concept of safety and the associated statistical probability of failure.