15.6.3. Frame Structures

Try these first

1. 1.

   What does lateral translation refer to in frame structures?

   Hint

   Think about how a building would sway.

2. 2.

   What is torsion in relation to structural behavior?

   Hint

   Consider the effects of uneven mass.

3. 3.

   What is the primary characteristic of torsional mode shapes in frame structures?

   • They primarily involve lateral translation.
   • They result from asymmetrical distributions.
   • They are non-existent.

   Hint

   Consider what happens in asymmetrical buildings.

4. 4.

   True or False: Combined mode shapes can only occur in perfectly symmetrical frame structures.

   • True
   • False

   Hint

   Think about how different shapes can react.

5. 5.

   Consider a frame structure with an uneven distribution of mass. Using modal analysis, how would you determine the effects of both lateral translation and torsion in its design?

   Hint

   Review eigenvalue problems from earlier sections.

6. 6.

   Design a frame structure intended to resist torsional forces. Outline key design elements that would help stabilize the building's response during lateral earthquakes.

   Hint

   Think about methods to counteract twisting effects.