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ENGINEERING, CS 2024 HSC 25c

A pin-jointed truss is shown. Member    has been determined to be 250 N in compression.
 

Complete the table. You must use the method specified to solve each component.   (6 marks)

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External reaction at (Mathematical method):

⤸  
 
 

 

Internal reaction of (Method of sections):

 
 
   
♦♦ Mean mark 46%.

Internal reaction of (Graphical):
 

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External reaction at (Mathematical method):

⤸  
 
 

 

Internal reaction of (Method of sections):

 
 
   
♦♦ Mean mark 46%.

Internal reaction of (Graphical):
 

ENGINEERING, CS 2023 HSC 22b

The diagram shows a child with a mass of 45 kg hanging 2 metres from the left end of a structure, and an adult with a mass of 85 kg hanging 1 metre from the right end.

 

  1. Calculate the reactions at and .   (3 marks)
      

 

  1. Complete the shear force and bending moment diagrams of the scenario described.   (3 marks)

 

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i.   

  
ii.    

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i.   

 
 
 

 

 
 

 
ii.    

ENGINEERING, CS 2016 HSC 26b

What are redundant truss members?   (2 marks)

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Redundant truss members:

→ A truss that carries no load under the conditions present.

→ It is important to note that as load conditions change, the truss may not actually remain redundant. 

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Redundant truss members:

→ A truss that carries no load under the conditions present.

→ It is important to note that as load conditions change, the truss may not actually remain redundant. 


♦ Mean mark 46%.

ENGINEERING, CS 2016 HSC 26a

A simplified diagram of a pin jointed truss of a hammerhead crane is shown. It is lifting a load of 54 kN.
 

  1. Calculate the reactions at supports and .   (4 marks)
  1. Determine the magnitude and nature of the force in member .   (2 marks)
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i.     Reaction at = 249 kN ↑

Reaction at = 123 kN @ 12.7° acting down and to the right.

ii.   Force in = 121 kN (Compression)

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i.

+  
 
 
   
     
+ ↑  
 
 
   
   

 

Reaction at = 249 kN acting vertically, up

Reaction at = 123 kN @ 12.7° acting down and to the right.
  


Mean mark (i) 52%.

ii.   

   

 
   
   

  
Force in = 121 kN (Compression)


♦ Mean mark (ii) 49%.

ENGINEERING, CS 2018 HSC 18 MC

The force is moved from joint to joint , as shown.
 

Which row of the table correctly describes the changes in the internal force in member and the reaction force at as a result of force moving from to ?
 

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→ Initially there is not force in member XY and no reaction at W.

→ When F is moved, a turning moment is created and needs to be countered by the reaction at W.

→ Member XY is also placed in tension, therefore both the force and reaction increase.

ENGINEERING, CS 2017 HSC 25a

A pin-jointed truss designed to support a roadside sign is shown.
 

  1. Determine the magnitude and direction of the reactions at and .   (4 marks)
  1. Determine the magnitude and nature of the force in member .   (2 marks)
  1. Explain why concrete would be a suitable material to support the roadside sign around point .   (2 marks)
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i.   


 

ii.   
 

iii.   Suitability of concrete

→ Easily poured and formed around the sign.

→ Relatively quick to cure.

→ Weather resistant.

→ Hardens and sets with high strength and hardness.

Show Worked Solution

 
 
   

 

Mean mark 56%.


  

 
   
   

 

 
   
   
 

 

 
 
 

 


♦♦ Mean mark (ii) 38%.

iii.   Suitability of concrete

→ Easily poured and formed around the sign.

→ Relatively quick to cure.

→ Weather resistant.

→ Hardens and sets with high strength and hardness.


♦ Mean mark (iii) 52%.

ENGINEERING, CS 2019 HSC 22c

The diagram shows some dimensions and forces associated with a telecommunications tower.
 

By considering any necessary reaction, calculate the magnitude of the forces in members and . State the nature of each force. Ignore the weight of the tower.   (6 marks)

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“

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Forces at Joint

Horizontal forces

To calculate vertical force at → use moments.


♦♦ Mean mark 36%.
 
 
 
 
   

    
Forces in Member → method of joints at

→ No horizontal forces

→ Member redundant and carrying no load

→

Member in compression (the force acting down on joint from member is 14.33 kN)

Force in N = 14.33 kN (compression)

  
Using Method of Sections → take moments about Joint

Find the perpendicular distance

 
 
º  
º  
 

 

  

 

ENGINEERING, CS 2022 HSC 26a

  1.  The diagram shows a tower crane being used in the construction of a building.
     

  1. Determine the number of 100 kg concrete blocks required to place the boom arm in equilibrium.   (2 marks)
  1. Under a different set of conditions, a wind force is applied, as shown in the diagram.
     

  1. Determine the magnitude and nature of the internal reaction in member A.   (6 marks)
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i.   

ii. 

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i.   Let the total weight of the concrete blocks

 
 
 
   
   
 

 
∴ 12 × 100 kg concrete blocks are needed for the counterweight.


♦ Mean mark (i) 46%.

ii.   Magnitude and nature of internal reaction

 
 
 

  
Taking the horizontal section shown:


  

 
 
 

  
∴


♦ Mean mark (ii) 43%.

ENGINEERING, CS 2020 HSC 25c

 

A cycle bridge has been constructed using a Warren girder truss loaded as shown. The diagram is drawn to scale.
 

By considering necessary loads and reactions, calculate the magnitude and nature of the force in member .   (6 marks)

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= 6.24 kN in tension

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Let the length of a member be 2 units

 
 
   

 

 
 
 
 
 
   

 
 
 
 
 
 
   

 
∴ Assumed direction was incorrect and reaction in is away from the joint.

∴  = 6.24 kN in tension


♦ Mean mark 48%.

ENGINEERING, CS 2021 HSC 25b

A truss is fixed to a wall at and as shown. Ignore the mass of the truss.
 


 

  1. Determine the horizontal reaction at .   (2 marks)
  1. Determine, using method of joints, the internal reaction in member . Indicate the nature of the force in the member.   (3 marks)
  1. Determine, using method of sections, the internal reaction in member . Indicate the nature of the force.   (3 marks)
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i.   

ii.   

iii.   

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i.   Horizontal reaction at

 
 
 
   

 

ii.   Method of joints at A
 
     

→Σ  
 
 
   

♦♦ Mean mark (ii) 41%.

iii.  Method of Sections

 
 
 
   
   

♦♦♦ Mean mark (iii) 30%.

ENGINEERING, CS 2021 HSC 7 MC

The diagram shows a section of a pin jointed truss in equilibrium. The force in Member 1 is 200 kN in compression.
 

Which row of the table identifies the magnitude and nature of the forces in Member 2 and Member 3?
 

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Show Worked Solution

→ The sum of horizontal forces and the sum of vertical forces must both be equal to 0.