This set of Prestressed Concrete Structures Multiple Choice Questions & Answers (MCQs) focuses on “Structural Forms for Aircraft Hangars”.
1. The structural forms generally used for aircraft hangers are compiled of:
a) 3 types
b) 2 types
c) 4 types
d) 6 types
Explanation: Over the last few decades, increased airway traffic has necessitated the development and use of large aircraft like Boeing-747 and Airbus-320 and the servicing of these aircraft requires large aircraft hangers with unrestricted space for easy movement of aircraft and the structures forms generally used for aircraft hangers are compiled as follows: prestressed concrete barrel shells, prestressed concrete folded plates, twin cantilever folded plate roofs.
2. The cantilever folded plate roof requires significantly lower quantities of materials like:
a) Concrete and prestressing cables
b) Shortcrete and prestressing cables
c) Fabric and prestressing cables
d) Reinforcement and prestressing cables
Explanation: Twin cantilever folded plate roofs with a central service complex and the continuous folded plate roof is stayed by prestressed concrete ties and this type of planning provides and unrestricted clear space of 60-90m on either side of the central service complex and the cantilever and folded plate roof complex requires significantly lower quantities of materials like concrete and prestressing cables due to the unique feature of the structural form.
3. The prestress concrete aircraft hangers normally require free spaces for:
Explanation: Prestressed concrete aircraft hangers normally require large column free spaces and the introduction of prestressed concrete in India in the year 1939 resulting in larger spans of column free structures suitable for aircraft hangers such as that planned for the Karachi airport in 1942.
4. In Karachi airport at that time in 1942 which were used:
a) High tensile steel wires
b) High compression wires
c) Normal wires
d) Long span wires
Explanation: At the time, the high tensile steel wires were imported from France and the cables were made by covering the wires with bitumen wrapped in sisal craft paper and the cables comprised 32 numbers of 5mm diameter wires providing a prestressing force of 660kn and prestressed reinforced concrete trusses of spans in the range of 18m with asbestos covering were planned to provide large column free space for the integral coach factory built at perambur madras as early as 1956.
5. An example to plan aircraft hanger using prestressed concrete which is ideally suitable for large spans:
a) Indian airlines airbus hanger
b) Spain airlines airbus hanger
c) American airlines airbus hanger
d) Africa airlines airbus hanger
Explanation: The present method is to plan aircraft hangers using prestressed concrete which is ideally suitable for large spans with reduced maintenance costs due to superior durability characteristics of prestressed concrete and an excellent example of this type is the roof of the Indian airlines hanger in Bombay.
6. The Indian airlines airbus hanger which was considered as world record:
a) Structure construction
c) Long cantilever span
Explanation: The structure comprises prestressed concrete folded plates cantilevering on opposite sides from the main service complex and the long cantilever span can be considered as world record for this type of construction which was chosen to achieve flexibility of lateral expansion without distributing the existing facilities.
7. The inclined struts supporting the prestressed concrete ties are provided with:
Explanation: The roof is formed by a very thin folded plate of 7.62m module with webs inclined at 45 degrees and the continuous folded plate is stayed by prestressed concrete ties and the inclined struts supporting the prestressed concrete ties and provided with Freyssinet hinges at the junction with the roof in order to permit free rotations.
8. The hanger provides a clear uninterrupted space of:
Explanation: The hanger provides a clear uninterrupted space of 91.4m long with an average height of 13m so that two airbus aircrafts can easily be parked in the hanger and also an expansion joint planned and provided at the centre divides the roof into two units of 45.7m each.
9. As the side walls are independent of the roof so that the hanger can be:
Explanation: The cantilever roof is estimated to deflect by 280mm near the tip under maximum wind effects and the safe movements of the sliding door is ensured by the provision of a concrete channel section of adequate depth at the tip of the roof and the hanger has been planned and designed to withstand the dynamic effect of wind gusts of the coastal zone during cyclonic wind reaching a speed of 160knmph and the hanger can also be widened whenever required as the side walls are independent of the roof and the airbus hanger was designed by STOP consulting engineers for the Indian airlines corporation.
10. Another planning example of planning an aircraft hanger is Boeing hanger at santa curv airport is in:
Explanation: Another planning example of planning an aircraft hanger is Boeing hanger at santa curv airport is in: Bombay the prestressed hanger provides an uninterrupted area of 101m by 45.73m and the roof consists of 10 barrel shells of 45.75m span with 12.2m chord width supported on longitudinal prestressed concrete edge beams and the frontal beams are also prestressed and the span over clear door openings is 48.8m and the overall depth of the beam is 6.1m the soffit of the beam and the aircraft hanger was planned and designed and constructed by gammon Indian limited for the international airports authority of India.
Sanfoundry Global Education & Learning Series – Prestressed Concrete Structures.
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