2021030821344120210307172503epss8 lab08 shakeliquefaction 2 .pdf

Student’s name: TA’s name: Sec0on:
EPSS 8 - Earthquakes
Lab8: Shake Table and Liquefac:on Tank
Due Week 10
In this lab, you will explore the behavior of scale models of buildings and of shaking soils.
[Some sections written in red in this lab are not applicable because we cannot do the
corresponding demos in class. Read the sections to understand the concepts but you may ignore
the questions in red sections.]
Part 1 (11 pts): Building resonance on a shaking table
Recap : For a propagating sine wave, the period is the time it takes for a cycle of wave to pass a
certain point in space and the frequency is the number of cycles passing a point per second. The
period is measured in seconds ( s ) and the frequency is measured in Hertz ( Hz ) or inverse seconds
( s
-1
). For example, a wave with a period T =2 s has a frequency f =1/ T =0.5
Watch this video:
In the video, the motor will shake the table and the 3 buildings with a uniform frequency. As the
motor speeds up, the frequency of shaking increases and the period of shaking diminishes. Each
building will respond differently to the shaking, depending on its natural frequency . When the
shaking frequency of the table matches the natural frequency of a building, the building will
shake with the largest amplitudes.
Start the movie and stop it after the title page (10s). Measure the height of each building on your
computer screen using a ruler and report the values in the table below. If you do not have a ruler,
use a lined page from a yellow pad and use the line spacing as the unit of length.
Watch the entire movie and take note of the frequency when the resonance is achieved for each
building. Fill up the frequency column in the table below. Then compute the period for each
building.
Hz .
Table: 2 pts per line (0.5, 1, 0.5)