EQ-11: QUAKE AFFECTS ON BUILDINGS
MATERIALS LIST
Electric shaking table with foam block inserts OR
Manual shaking table with single foam covered shaking platform
Building blocks of wood and Lego-type (hook together)
Building frames and braces
2 small model houses with 2 different foundations
2 wooden trays to contain DRY gravel and sand
1 water tank and pyramid building
1 container of gravel and 1 of sand
Earthquakes
Effects on Building
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QUAKE AFFECTS ON BUILDINGS
Fall 1997
OBJECTIVES:
To study earthquake effects on different types of structures and substrates
EQ - 11
SCIENCE THEMES:
Energy, scale and structure, systems and interactions
PROCESS SKILLS:
Observing, comparing
GRADE LEVELS:
4–6
FOCUS WORDS:
reinforced, diagonal bracing, paneling
BACKGROUND INFORMATION:
Much has been learned about the effects of earthquakes on buildings and other structures from the
long history of damaging earthquakes around the world. This knowledge has been incorporated in
building codes and building practices in many earthquake-prone countries.
In California, a good example of learning from past quakes was the passage of the Field Act shortly
after the devastating 1933 Long Beach quake. Though school buildings were hopelessly damaged
by the quake, few were injured inside; the quake struck in the early evening when school was out.
The Field Act established tough earthquake-resistant building codes for public schools in
earthquake-prone areas.
In general it has been found that wood frame structures often fare better than adobe or
unreinforced brick buildings, and that the main hazards with older buildings are loosely attached
roofing tiles, parapets (freestanding walls that border roofs and balconies), unreinforced brick and
brick facing, ornaments and decorative cornices.
Also, buildings built before the 1950's may not be securely attached to their foundations, and
earthquake hazard that may result in serious structural damage.
Newer buildings have been planned with earthquakes in mind, especially in Japan and California
where the science of earthquake engineering has become an integral part of building design and
construction. Designing safe, quake-resistant structures can be complex, for earthquake waves and
ground motions can come in so many different shapes, sizes, frequencies, and directions.
Even though buildings may be safely constructed, we still must prevent interior rooms and fixtures
from being earthquake hazards. Knowing how quakes affect buildings and making safety
improvements where possible, are the first steps toward becoming quake ready.
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Effects on Building
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ACTIVITY: (15 minutes)
Place SHAKING TABLE on a sturdy table. Make sure the switch is in the off position and then plug
the table in.
Have FOAM INSERTS, BUILDING BLOCKS, BUILDING FRAME AND BRACING, the SMALL
MODEL HOUSES and FOUNDATIONS, and the TALL and SHORT BUILDINGS ready for
demonstration on the shaking table.
SUGGESTED INTRODUCTION:
It is difficult to predict exactly how an earthquake will affect a building, but we know from
earthquakes past that the effects can be severe. We can learn how to reduce many of the most
harmful effects by looking at some of the interactions between QUAKES & BUILDINGS.
AUDIENCE:
For Younger children — Focus on the SHAKING TABLE demonstrations, reassuring them that
buildings today are built to withstand a great deal of earthquake shaking.
For Older children — Stress the variety of effects quakes can have on different structures, and the
difficulty in designing completely earthquake-proof structures.
Adults — Discuss their own homes and workplaces as examples of how quakes might effect
buildings. Refer them to further guides to assessing their hazards and ways of protecting the
structures where they live and work.
ASK:
In an earthquake, does the safety of your home, school or workplace depend on how
the buildings are built?
RESPONSE: Yes. Buildings today are more earthquake-resistant than older buildings, though
safety improvements may be necessary.
EXPLAIN:
Using the shaking table we can demonstrate what effects earthquakes might have on
different kinds of buildings and construction methods.
EXPLAIN:
It's impossible to show exactly what will happen to a certain kind of building
method and earthquake wave effects.
DO:
Set the foam blocks in place and ask for two volunteers — one to construct a
building out of the wooden building blocks, representing unreinforced brick, and
one to construct a building out of the plastic, Lego-type blocks representing
reinforced brick. Both structures should be built on top of the foam blocks. Make
sure that the Velcro bottom foundations are used for the base of the structures.
DO:
Point out that there are a variety of methods of reinforcing brick or masonry.
DO:
Have others repeat the demonstration with their own building designs.
ASK:
Which building is going to have less damage in an earthquake and why?
DO:
Turn the shaking table on and slowly increase the shaking until the effects are clear.
RESPONSE: Encourage a variety of responses and explanations. You shouldn't need to go
beyond #6 or #7 on the dial to see the different effects.
ASK:
What happened?
RESPONSE: The unreinforced wooden blocks fell apart, while the reinforced plastic blocks held
up to strong shaking.
EXPLAIN:
Earthquakes
In wood frame buildings, diagonal supports and paneling help to make the building
Effects on Building
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more earthquake safe.
DO:
Demonstrate this with the building frames with the diagonal bracing and the panel
bracing on top of the shaking table.
First show the frame without any bracing, then demonstrate the effects of adding
either the diagonal brace or the panel.
DO:
Demonstrate what happens to the small model houses when one is securely attached
to a solid foundation with Velcro and the other is not.
EXPLAIN:
Building frames are usually secured to their concrete foundations with large bolts.
Buildings built before 1950 may not be adequately secured.
DO:
Place the tank and the pyramid-shaped buildings on top of the foam block.
ASK:
Which building will be affected first by earthquake shaking?
DO:
Turn on the table and slowly increase the shaking until the tank topples.
DO:
Point out that new building designs are often more earthquake-resistant.
NOTE:
You may mention that the pyramid design places more of its weight at the bottom
than at the top, making it more stable.
Other earthquake minded designs use suspension systems, flexible joints, deep
foundations, and many other techniques for withstanding earthquake activity.
DO:
Attach the tall and short frames to the foam board with bolts and wing nuts.
ASK:
Which building will be affected more in slow shaking?
Which by fast shaking?
Why?
DO:
Turn the table on and very slowly increase to a high level, then decrease the speed of
shaking.
DO:
Have everyone observe and discuss the results.
RESPONSE: The tall building is more affected by slow shaking, the short, by fast shaking.
EXPLAIN:
Neither structure is more or less safe — the effects depend on the kind of earthquake
that strikes. This shows how difficult it is to create "earthquake-proof" structures.
DO:
Mention that most earthquake injuries are due to falling objects, so take cover
during a quake!
FOLLOW-UPS:
Students can create other model buildings for testing on the shaking table, using a variety of
materials and construction methods that simulate actual building constructions. Make a list of the
most and least successful quake-proof designs.
Find out more about the design and construction of your home, school, workplace, etc., and how
they can be made more earthquake safe.
Compile a list of ways that structures can be modified for greater earthquake safety.
REFERENCES:
Iacopi, Robert. Earthquake Country, pp. 36 - 41
Time-Life Editors. Earthquake, Planet Earth 1, pp. 153-155.
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Effects on Building
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Yanev, Peter. Peace of Mind in Earthquake Country, pp. 07-219
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Effects on Building
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