Prestressed Concrete Structures Multiple Choice Questions on “General Features”.
1. Which is more economical to use along precast reinforced concrete trusses?
a) Roller member
b) Hinge member
c) Tie member
d) Flange member
Clarification: It is more economical and convenient to use precast reinforced concrete trusses with a prestressed tie member covering roofs of industrial structures such as wave houses workshops having spans exceeding 15m.
2. The configuration of truss depends upon the shape of?
Clarification: The configuration of the truss depends upon the shape of the roof and its general layout and in Russia trusses are generally adopted for industrial buildings having spans greater than 18m and a central I girders and the deck is suspended by cable stays comprising parallel wire cables of BBR-HIAM type with their own anchorage system.
3. Which type of trusses in case of structure located in coastal areas?
b) Tensile trusses
c) Concrete trusses
d) Tensile & Concrete trusses
Clarification: In the case of structures located in coastal area where humidity and temperature are high, it is preferable to use concrete trusses in place of steel trusses which are vulnerable to rust and deterioration due to high humidity.
4. The use of concrete trusses will considerably reduce __________
Clarification: The use of concrete trusses will considerably reduce the maintenance cost in comparison with steel trusses which require periodical painting at shorter intervals and the trusses in structural member are of circular, cylindrical, hollow etc used for various heavy structures the stress analysis is done by considering all the factors which influence the trusses.
5. Most favorable configuration of the top chord is obtained in __________
a) Bow strung truss
b) Elevated truss
c) Curved truss
d) Termed truss
Clarification: The most favorable configuration of the top cord is obtained in the bow strung truss and the web or diagonal members are subjected to very heavy tension and hence ideally suited for prestressing and top chords and bottom chords are considered in case of precast and insitu cast concrete assuming the pretensioned beam as unpropped and propped.
6. The cables strayed bridges are preferred to convential suspension bridges due to reduction of __________
b) Bending moment
Clarification: Cable strayed bridges are preferred to convential suspension bridges for long spans mainly due to reduction in bending moment in the stiffening girder resulting in smaller section of the girders leading to considerable economy in overall costs highway bridges can be built of prestressed concrete with spans up 700m and rail bridges up to span range of 400m.
7. The suspension bridges require a stiffening girder for covering the span, with a __________
a) Flexural stiffness
b) Tensile stiffness
c) Compressive stiffness
d) Principle stiffness
Clarification: A comparative study also indicates that a suspension bridge requires a stiffening girder with a flexural stiffness which must be about ten times larger than that required for a cable stayed bridge covering the same span and suspension bridge requires additional heavy anchor blocks which can be prohibitively costly if the navigation clearance is high and foundation conditions poor.
8. The second Hooghly bridge (vidyasagar sethu) at Kolkata is an excellent example of this?
a) Cable strayed bridge
b) Cable tensioned bridge
c) Cable stressed bridge
d) Cable strained bridge
Clarification: The second Hooghly bridge (vidyasagar sethu) at Kolkata is an excellent example of: Cable strayed bridge comprising a main span of 457.2m and two side spans of 182.8m each and the deck is made of concrete slab 230mm thick two outer steel I girders 28.10m apart.
9. The bridge provides how many large carriage ways?
Clarification: The Bridge provides for two 3- lane carriage ways 12.3m each and 2.5m floor paths and the cable stayed bridge costing 600 million rupees was found to be cost effective in comparison with other types.
10. The world’s tallest and longest cable stayed bridge is located in?
Clarification: The world’s tallest and longest cables stayed bridge is located in France and the French bridge is considered to be an engineering feat since some of the bridge pillars rise gracefully to a height of more than 300m and the bridge is located outside the French town of milliance and is 2.46km long and the bridge designed by the famous British architecture sir norman Foster, is currently the world’s tallest and longest cable stayed bridge and described by many as an astounding engineering feat.