The Indianapolis times. [volume] (Indianapolis [Ind.]) 1922-1965, 1934-10-08
Today S Science
BY DAVID DIETZ

ENGINEERS are convinced that the dangers Of
II earthquakes be minimized by building
structures so that they will Withstand the shock.
With this end in view the department of civil en-
cheering at Massachusetts Institute of Technology
is making study of the effect OF earthquakes on
elevated water tanks.
It is hoped that these studies will lead to methods
of safeguarding public water supplies in sub
ject TO seismic disturbances.
The Importance of this study is emphasized by the
fact that in the rather slight earthquake at Long
Beach, Cal. last year, surprisingly large number of
elevated tanks damaged, some of them so seri-
OuSly that it was necessary to dismantle them.
The slight quakes felt in the outskirts of San
Francisco only few days ago. while doing no more
than rafting a few pictures the walls of homes,
nevertheless served TO emphasize the fact that CAL
nornia IS one of the worlds seismic regions.
In the historic and disastrous San Francisco
earthquake, the fire which followed the quake did
more damage than the quake itself. But the quake
not only responsible for starting the fire but for
making it impossible to fight it. For the quake
broke water mains everywhere and destroyed the
CityS water supply.
OBSTRUCTION of a city'S water supply intro
II duceS fire hazard and health hazard, for
many epidemicS start rapidly with the break
down OF proper sanitation.
1t was these considerations which led the Fac
tory Mutual Fire Insurance Companies to sponsor
the present studies Arthur c. Ruge, research asso-
ciate in the laboratory of Sesology carrying on
the researches.
He is employing miniature water tanks in his
studies and observing the effect of laboratory
created earthquakes upon them. He built model
Of 60000-gallon, l00-foot tower tank a scale Of
l to so. This mounted on a table.
Miniature earthquakes obtained by the
simple method of shaking the table
Comparing the results of his tests with the
monty accepted method of designing tank towers to
resist earthquakes he came to the conclusion that
the present method was inadequate.
Present methods Of designing elevated tank
towers 10 resist earthquakes found 10 be con-
siderably on the unsafe side" Mr. Ruge reports.
They do not even give general indication Of the
actual stresses"
NHR. RUGE has come to the conclusion that there
WI must be radical changes in the design of wa
ter towers for seismic regions
The type of tower now so common was not de-
veloped for earthquake resistance he says, but
merely 10 fulfill the purpose of eevatlng the water
supply on a structure which must resist a certain
amount Of wind force in addition to carrying the
vertical load. For this it is practically ideal but
there IS reason 10 accept It the ideal structure
for outstanding earthquake motions"
The present researches. it is hoped will reveal
what the ideal structure is for seismic region.
In his experiments Mr.. Ruge uses equipment
which both magnlfieS and records the movements Of
the model. Levers Connected TO the model and the
shaking table magnify the movements and cause
them TO be recorded moving strip OF photog-
raphic film. The film IS then developed like mo-
ton picture and studied az leisure.