Evening star., 1922-02-06

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!. .Deubtlesssit +wiill d dies;Ve1Sa. that their
lHgures VIII nor DE I'm 1uffs agreement
t4with recotded eatEsssks However. it
does not appear that the failure was
due to the pulling apart of any steel
section and the writer would not ex-
pect such to be the case.
Glaring Faults Found.
Some glaring faults in the sections
of the trusses are found. The splic-
ing Of both the tension and compress
sion fianges of the several trusses
was inadequate and improperly done,
SO that the stresses at the spices
were nearly double the allowable
safe stresses. However. failure did
not result from this cause, although
it was tempting Providence to try
such a reckless experiment over the
heads of unsuspecting audiences.
Evidently no thought was given the
fact that truss No. IL bolted to lug
angles on the top of column No. 2,
caused large bending stresses in the
column No. 2 due to the detection Of
the truss itself. This tall, slender
column with inadequate connection
at its base was unable to resist bend
ing stresses and simply tended to tin
on on, ITS base and ip fact at the collapse
1t is difficult to determine what the
loads and stresses were in the bal
cony framing. An addition was made
10 the balcony last summer, the de-
taiis OF which the writer has not
seen. A glance at figure l will show
that any disturbance of the eduili-
Drlum of the framing at either Of the
supports over the two columns. Nos
or 3, would be fatal
1t is evident that beam Bal is the
poorly supported member of the roof
framing. This beam is shown to be
OF the same size as other beams in
the roof, which had much. smaller
areas to support. Beam BAL is bent
at present, which. while not surpris-
ing. is conf1rmatory of the view that
it was bent out of line by severe
overlooking. Here is case where
the snow load was larger factor
than in the case Of the trusses and
it caused probably more than 25 per
cent increase TO the dead load
& Would Upsent Main GirSeE. :
This beam being SO. seriously over
loaded would tend to buckle sidewise.
and if it started to buckle it would
bring pull upon the top fange of
the vertical channel on which its
east end rested. and that channel
would instantly collapse. with the re-
suit that the angle strut above COL
umn No. 2 would be pulled toward
the east. Column No. 2 would. be
restrained by the strut. directly under
Bal. from falling in that direction.
with the result that it would be car
ried south and slightly east, as was
the case. This would instantly pull
the main girder off Of its wall sup
port and the entire roof would COL
lapse.
tions taken by the fallen trusses and
columns that had supported the roof
shows that the movement was toward
the south. that ds away from. the
stage. The north. end of the main
truss was pulled on Of 1T & bearing on
the top of a tMenty-inch BEAM that
simply rested upon the, wall, without
tipping that tweHty-inchy' beam over.
which Indicates u very sudden. acticBi
Ks this truss fell; lit, did not scrape
down the inner face of the walk but
cleared it. entirely. showing that the
movement was not toward the north,
nor even straight downward, but
toward the sonth, As none Of the
beams. or trusses were. attached to
moved off of them when the collapse
began and the, unstable condition Of
the two slender columns, Nos. 2 and
3, offered no resistance to the first
Gripping force, which the writer be-
lieves developed in the beam Bal
and because of the weak sup
ports under that beam the collapse
Bal.
The change in temperature of the
roof slab from 80 degrees to 80 de-
grees would result in lengthening
the distance between columns Nos.
2 and 3 a quarter Of an inch.
il ittis assumed that the walls can
not be pulled in that much by the
stresses in the roof construction.
From this it is evident that even the
temperature of the roof probably
had an influence on the stability of
the structure, as no means were
adopted to care for these irresistible
stresses. -.
Plans Need, Much Study. 4.
1t requires painstaking study of
plans to discover whether or not
work and each detail of any kind
Of construction is adequates One may
not grasp the facts in q hurried, cur
sorry examination Of plans and if
the public is to depend absolutely on
government supervision to discover
Incompetence, it will be important to
have appropriations or building per-
mits fees sufficiently large to support
building inspection department with
2 large corps OF trained engineers
and inspectors. Even then it will be
the designing and supervision Of all
buildings except very simple resi-
dences and similar structures shall be
intrusted only to architects who will
agree to retain competent engineers
to make their structural designs or
engineers to collaborate with their
architects.
Architects generally do not wish
to pay. out of their fees adequate
compensation to competent engineers
for designing and supervising serv-
ices. Therefore they are too often
inclined to economize and omit en-
ploying competent structural engin-
GERS as designers for what Is afterall
the most vital part of the building.
It should be borne in mind that it is
human nature mot to spend more
Eineer is generally hidden out Of.
sight.
T. l. Condron, Born sin.D. C.,
Looked Uron as Leader
In Engineering Circles
Theodore L. Condron, c. E., born in
Washington, D. CO. and educated In
the private and public schools here.
After: several years In the employ of
Ne u..Beuerdge .tn9E Nulin & Martin
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