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Design of Steel Structures Mcqs

Q:

For gantry girders carrying hand operated cranes, the vertical forces are increased by____ for impact allowance

A) 10% of maximum static wheel load B) 25% of maximum static wheel load
C) 10% of weight of crab and weight lifted on the crane D) 20% of weight of crab and weight lifted on the crane
 
Answer & Explanation Answer: C) 10% of weight of crab and weight lifted on the crane

Explanation: For gantry girders carrying hand operated cranes, the vertical forces are increased by 10% of maximum static wheel load for impact allowance. The lateral forces can be increased by 5% of weight of crab and weight lifted on the crane.

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73
Q:

For gantry girders carrying electrically operated overhead travelling cranes, the lateral forces are increased by ____ for impact allowance.

A) 10% of weight of crab and weight lifted on the crane B) 20% of weight of crab and weight lifted on the crane
C) 25% of maximum static wheel load D) 50% of maximum static wheel load
 
Answer & Explanation Answer: A) 10% of weight of crab and weight lifted on the crane

Explanation: For gantry girders carrying electrically operated overhead travelling cranes, the lateral forces are increased by 10% of weight of crab for impact allowance and weight lifted on the crane. The vertical forces can be increased by 25% of maximum static wheel load.

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147
Q:

Which of the following loads are not considered in the design of gantry girders?

A) longitudinal loads B) gravity loads
C) lateral loads D) wind loads
 
Answer & Explanation Answer: D) wind loads

Explanation: The loads considered in the design of gantry girders are vertical loads or gravity loads, longitudinal loads, lateral loads and impact loads. The vertical force is the reaction from crane girder, acting vertically downward. The longitudinal thrust is due to starting and stopping of crane acting in longitudinal direction. The lateral thrust is due to starting and stopping of the crab acting horizontally normal to the gantry girder.

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85
Q:

Which of the following is correct regarding gantry girders?

A) It is laterally supported except at the columns B) It is subjected to impact load
C) It should not be analysed for unsymmetrical bending D) It is not subjected to longitudinal load
 
Answer & Explanation Answer: B) It is subjected to impact load

Explanation: Gantry girder are different from beams in buildings. It is generally laterally unsupported except at the columns. It is subjected to impact load. It must be analysed for unsymmetrical bending because of lateral thrust from the starting and stopping of the crab. It is subjected to longitudinal load due to starting and stopping of crane bridge itself. They are always simply supported.

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80
Q:

Which of the following is not true regarding longitudinal stiffeners?

A) longitudinal stiffeners increase buckling resistance considerably as compared to transverse stiffeners B) they consist of plane section for welded plate girder
C) first horizontal stiffener is provide at one-fifth of distance from compression flange D) first horizontal stiffener is provide at neutral axis
 
Answer & Explanation Answer: D) first horizontal stiffener is provide at neutral axis

Explanation: Longitudinal stiffeners are also called horizontal stiffeners. They increase buckling resistance considerably as compared to transverse stiffeners when the web is subjected to buckling. They consist of angle section for riveted/bolted plate girder and plane section for welded plate girder and are provided in the compression zone of the web. The first horizontal stiffener is provide at one-fifth of distance from compression flange to tension flange. If required another stiffener is provided at the neutral axis.

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36
Q:

The effective length of intermediate transverse stiffener is taken as

A) 2 times the length of stiffener B) 0.7 times the length of stiffener
C) 1.4 times the length of stiffener D) 0.5 times the length of stiffener
 
Answer & Explanation Answer: D) 0.5 times the length of stiffener

Explanation: The effective length of intermediate transverse stiffener is taken as 0.7 times the length of stiffener. The intermediate transverse stiffener is provided mainly to improve shear buckling resistance of the web.

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31
Q:

What is the stiff bearing length?

A) length which cannot deform appreciably in bending B) length which deform appreciably in bending
C) length of outer end of flange D) length of web
 
Answer & Explanation Answer: A) length which cannot deform appreciably in bending

Explanation: The stiff bearing length of any element b? is that length which cannot deform appreciably in bending. To determine b?, the dispersion of load through a steel bearing element should be taken as 45? through solid material, such as bearing plates, flange plates, etc.

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66
Q:

The function of bearing stiffener is to

A) improve buckling strength of web B) preclude any crushing of web
C) restrain against torsional effects D) increase buckling resistance of web
 
Answer & Explanation Answer: B) preclude any crushing of web

Explanation: The function of bearing stiffener is to preclude any crushing of web at locations of heavy concentrated loads. Thus, they transfer heavy reactions or concentrated loads to the full depth of web. They are placed in pairs on the web of plate girders at unframed girder ends and where required for concentrated loads.

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