4.4. Problems

Try these first

1. 1.

   Define static determinacy.

   Hint

   Consider how many unknowns and equations are in a system.

2. 2.

   What is a free-body diagram?

   Hint

   Think about what you need to include in your drawings when analyzing forces.

3. 3.

   What does static determinacy allow us to do in frame analysis?

   • Calculate forces without restrictions
   • Use equilibrium equations
   • Ignore internal forces

   Hint

   Which concept connects with equilibrium equations?

4. 4.

   True or false: A frame is statically indeterminate if the number of equations is less than the number of unknowns.

   • True
   • False

   Hint

   Think about the relationship between unknowns and equations.

5. 5.

   Given a cantilever beam with a point load at its free end, derive the shear and bending moment equations along the beam.

   Hint

   What are the effects of the load at the free end on the reactions?

6. 6.

   Analyze a bridge truss loaded with several members and loads, identify which members are in tension or compression.

   Hint

   Start with joints where results yield the least unknowns.