Structures - Static of rigid bodies

Function and Applications

With this kit, students can apply loads at different points on the non-redundant truss and the redundant truss to investigate the tensile and compressive forces in each truss member.

This kit consists of a redundant member that can be turned on and off using the thumbscrews.

• When the redundant member is detached from the other 6 truss members, students can learn to analyze the 6 truss members using the nodal point method and Ritter's section method using Bow's notation. This experimental setup is used to analyze the non-redundant truss.
• If the redundant member is connected to the other 6 truss members, students can learn to analyze the 7 truss members using the principle of virtual work, the nodal point method, or Ritter's intersection method. The students can also determine the redundancy with the test (m+r) <=> (2j). The redundant element has a twisting mechanism with which its length can be easily adjusted. This experimental set-up is used to investigate the redundant truss.
  

Benefits

• Students can learn to calculate the theoretical beam forces and compare them to the experimental beam forces.

• Two suspension positions allow students to explore the idea of redundancy in frameworks and see how the load is transferred through the system.

• A magnetic pulley allows students to apply inclined loads.

• The construction is made from 2 mm thick mild steel and provides a strong and rigid base for conducting experiments.

Equipment and Technical Data

There are 7 load cells on each of the 7 truss members, which are connected directly to an LCD display for output and to the USB interface for data acquisition. The LCD display shows the output with positive or negative values so that the students can recognize which truss element is under tension or compression. Using the zero buttons next to the LCD display, students can set the load cell output to zero and restart the experiment each time.

Learning objectives

• Determination of limb forces when:
  • The position and angle of the applied load are different
  • The mass of the load increases
  • The truss has non-redundant members
  • The truss has a redundant member
• Bow's notation
• Method of Joints
• Ritter's method of Sections
• Method of Virtual work
• Determination of redundancy with the test (m+r) <=> (2j)
• Determine the tensile or compressive forces for each bar