Prestressed Concrete Structures Multiple Choice Questions on “Composite Structural Members”.
1. The composite sections provide one monolithic action between ______________
a) Prefabricated units
b) Post fabricated units
c) Pasteurized units
d) Tensioned units
Clarification: In a composite construction precast prestressed members are used in conjunction with the concrete cast in situ so that the members behave as monolithic unit under service loads and stirrups produced from the prestressed unit into the added concrete or by castellation on the surface of the prestressed unit adjoining the concrete which in cast in situ.
2. The high strength prestressed units are used in which zone?
a) Compression zone
b) Tension zone
c) Span zone
d) Beam zone
Clarification: The high strength prestressed units are used in the tension zone while the concrete which is the cast in situ of relatively lower compressive strength is used in the compression zone of the composite members and the composite action between the two components is achieved by roughening the surface of the prestressed unit on to which the concrete is cast insitu thus giving a better frictional resistance.
3. The Composite construction was first tries for a motorway bridge?
Clarification: The phenomenon of differential shrinkage between the concrete cast insitu and the prestressed units also contributes to the monolithic action of the composite members and composite construction was first tried for a way bridge in 1940 and detailed calculations were prestressed by morch in 1943.
4. Due to the effect of composite action sizes of precast prestressed units can be ______________
Clarification: The sizes of precast prestressed units can be reduced due to the effect of composite action and low ratio of size of the precast unit to that of the whole component member and appreciable saving in the cost of steel in a composite member compared with a reinforced or prestressed concrete member.
5. In many cases precast prestressed unit serve as ____________
a) Supports and dispences
b) Girders and dispences
c) Area and dispences
d) Beams and dispences
Clarification: In many cases precast prestressed units serve as supports and dispense with the form work for placement of insitu concrete and composite members are ideally suited for constructing bridge decks without the disruption of normal traffic.
6. The efficient utilization of material in a composite section in which the low and medium strength concrete resists?
a) Tensile forces
b) Principal forces
c) Compressive forces
d) Axial forces
Clarification: The efficient utilization of material in a composite member in a composite section in which the low and medium strength concentration of insitu construction resists compressive forces while the high strength prestressed units resist tensile forces.
7. The combination of light weight concrete for the cast insitu slab results in reduced ____________
a) Live loads
b) Dead loads
c) Constant loads
d) Limited loads
Clarification: Combination of light weight concrete for the cast in situ slab results in reduced dead loads leading to economy in the overall costs and the precast prestressed units which require skilled labour and workmanship can be cast in a factory or casting yard and conveyed to the site of construction.
8. In case of conventional method there will be a steel beam and slab construction in which the components carries their?
a) Entire load
b) Half load
c) Span load
Clarification: In case of conventional method, there will be a steel beam and slab construction in which the components carries their entire load transmitted by the slab and there will be no composite action between the members when compared than conventional method of construction the precast unit’s method facilitates a greater structural efficiency.
9. The main components of the composite beam are prestressed precast stem and ____________
a) A cast insitu flange
b) A cast insitu beam
c) A cast insitu slab
d) A cast insitu column
Clarification: The main components of the composite beam are prestressed precast stem and a cast insitu flange and the prestressed precast stem of higher grade concrete is prepared in a factory while the flange having a concrete of lower grade is used for casting is done at the site.
10. To attain the composite action the precast stem and the flange is ____________
a) Laced together
b) Tied together
c) Keyed together
d) Cutted together
Clarification: To attain the composite action the precast stem and the flange is keyed together and facilitates in carrying the heavier loads effectively between the prefabricated beam and cast in situ slab shear connection should be provided in which they act as one unit and resist the loads by composite action as in reinforced concrete T beams.