Prestressed Concrete Structures Multiple Choice Questions on “Analysis of Truss”.
1. Based on experimental investigations, the members of truss are analyzed on assumption that the joints are _____________
a) Rollers
b) SSB
c) UDL
d) Hinged
Answer: d
Clarification: Based on theoretical and experimental investigations, it well established that the forces in the various members of the truss are analyzed on the assumption that the joint are hinged in the case os steel, reinforced concrete and prestressed concrete trusses.
2. Which action of joint does not affect the forces developed in the members?
a) Plasticity
b) Rigidity
c) Flexural
d) Ductile
Answer: b
Clarification: The rigidity of the joint does not significantly affect the forces developed in the members and hence the analysis is generally carried out on the assumption of hinged joints and the action of rigidity joint is flexible and tough enough towards the deflection.
3. The trusses are analyzed for dead, wind and ____________
a) Wave loads
b) Fire actions
c) Snow loads
d) Tensile loads
Answer: c
Clarification: The trusses are analyzed for dead, wind and snow loads applied to the joints of the top chord and the load of suspend mechanical handling facilities is applied at the panel points of bottom chord and these loads are analyzed against check for deflection for safety of structure.
4. When loads are applied to the chords the bending moment developed are determined by assuming chord as a ____________
a) SSB
b) Continuous
c) Point
d) UDL
Answer: b
Clarification: When loads are applied to the chords of a truss between the panel points and the bending moment developed are determined by assuming the chord as a continuous beam with spans equal to the distance between the joints.
5. Trusses must be analyzed for forces developed during ____________
a) Fabrication and erection
b) Twisting and lining
c) Grouting
d) Shortcrete
Answer: a
Clarification: Trusses must also be analyzed for forces developed during fabrication and erection and initial stresses developed due to the prestressing of the bottom chord members should also be considered in the design of trusses.
6. One of the functions involved in construction management is?
a) House owners
b) Tax planners
c) Land
d) Area of site
Answer: b
Clarification: Construction of any structure forms only a small part of the whole gamut of construction management and the modern approach in construction management involves several diverse functions like designers, estimators, constructors, supervisors, accountants, financial managers, corporate secretaries, tax planners working under professional managers.
7. Which methods are widely used in project works?
a) PERT
b) CRT
c) TRC
d) WRE
Answer: a
Clarification: Critical path method of project evaluation review techniques (PERT) are widely used in the management of project work and with the advent of computers, data processing, preparation of working drawings, work scheduling, materials management, controlling the various activities of the project and upgrading the various tasks have become more simpler and they can be efficiently handled with less paper works.
8. The grade of concrete used for construction of prestressed concrete structures is?
a) Heavy mix concrete
b) Design mix concrete
c) Partially mix concrete
d) Fully mix concrete
Answer: b
Clarification: The most important consideration in the construction of prestressed concrete structures is the design, production and control of high strength concrete with desirable properties the minimum grade specified in the Indian standard code IS: 1343: 2005 for post tensioned concrete is M30 and for prestressed concrete work it is M40, the code also specifies the only Design mix concrete should be used to ensure the desired strength and durability.
9. The cement content limit is not permitted unless special consideration has been considered in design?
a) 300
b) 400
c) 375
d) 475
Answer: d
Clarification: The cement content exceeding 475kg/m3 is not permitted unless special consideration has been considered in design to the increased risk if cracking due to drying shrinkage in thin sections or to early thermal stresses in thick sections and the Indian standard code also prescribes the minimum cement content together with the corresponding maximum free water cement ratio for different types of cements when prestressed concrete likely to be exposed to sulphate attack.
10. What is the aim of workability is to use the lower percentage?
a) Coarse aggregates
b) Fine aggregates
c) Gravel
d) Sandstone
Answer: b
Clarification: The aim should be to use the lowest percentage of fine aggregates which is consistent with the job conditions and which will permit placing of the concrete without honey combs and finishing it to a satisfactory surface and for high strength concrete used for prestressed concrete structures, the degree of workability as categorized in Indian standard code IS: 456-2000.