8.9. Base Excitation and Response

Try these first

1. 1.

   What is base excitation in structural dynamics?

   Hint

   Think about an earthquake and how the ground moves.

2. 2.

   Define relative displacement.

   Hint

   Consider how a building moves compared to the ground underneath it.

3. 3.

   What does the equation mx¨(t) + cx˙(t) + kx(t) = -my¨(t) represent?

   • Static load analysis
   • Base excitation due to ground motion
   • Thermal expansion

   Hint

   Look for the part addressing ground movement.

4. 4.

   True or False: Relative displacement considers only the motion of the structure.

   • True
   • False

   Hint

   Think about how displacement measurements are made.

5. 5.

   A building experiences a base excitation due to an earthquake where the ground accelerates at 2 m/s². If the mass of the building is 1000 kg, calculate the dynamic force exerted on the building.

   Hint

   Use the mass and acceleration to find the force.

6. 6.

   Discuss the implications of phase angle in a building designed in an earthquake-prone zone. What considerations should be factored into its design?

   Hint

   Think about ways to reduce impact during resonance.