13.1.3. Sign Convention

Try these first

1. 1.

   What is a positive moment defined as in structural analysis?

   Hint

   Think about the direction of rotation.

2. 2.

   Name the two types of coordinate systems used in structural analysis.

   Hint

   One corresponds to overall structure, the other to elements.

3. 3.

   What does a positive moment signify in structural analysis?

   • Clockwise rotation
   • Counter-clockwise rotation
   • No rotation

   Hint

   Think about the direction when defining moments.

4. 4.

   True or False: The global coordinate system uses lowercase axis labels.

   • True
   • False

   Hint

   Remember the distinction between global and local labels.

5. 5.

   Given a truss structure with various loading conditions, determine the sign conventions for all moments around each node given both counter-clockwise and clockwise applied forces.

   Hint

   Draw the truss and label forces carefully.

6. 6.

   Write a small program snippet that computes the moments in a beam based on a given set of forces, utilizing the defined sign conventions. Explain your approach.

   Hint

   Define your positive rotation carefully in the code comments for clarity.