The Marlboro democrat. [volume] (Bennettsville, S.C.) 1882-1908, 1904-07-01

Wilson differs from actual facts as to
the sectional area Of the different
girdeFs. From what source he has
obtained these sizes cannot deter
mine. They correspond neither with
original or revised designs nor with
the show drawings or with actual
measurements Of the work in place.
In this connection beg to call atten-
tion to the fact, that in every single
instance found that actual work In
place Is strictly In accordance with
the shop detail drawings, but that
these have not been prepared in &C.
cordance with the design furnished
the architect by the American Bridge
company.
In the table attached I have thus
shown three different sets of sizes for
each Of the main girders. 1t will be
seen that the siz.s assumed and used
by Mr.. Wilson in his calculations are
materially smaller than the actual
sizes taken from measurements of the
work in place, which have, of course,
used in my calculations.
NOT SERIOUSLY OVERLOADED.
Those tables alone are sufficient to
disprove the correctness of Mr.. Will
sons calculations, and show that he,
by mis- own methods, would have OBJ
tanned very different results had he
used the correct flange areas.
My calculations furthermo e dis
prove, with no uncertainty, the state.
ment that the girders are seriously
overloaded and show cOnclusively that
in no case Is the factor Of safety less
than 3.l3, in some cases more than 4 !;
and in every instance, therefore, are
the stresses we'll within the elastic
limit.
AS regards the stone bearing blocks
under north end Of girders No. or
G1, these are the only parts Of the
supports Of the dome which warrant
criticism. And yet they are within
safe limits under ordinary circum-
stances. The reaction at north end
Of girders Is 25O,00O pounds. This
should be considered as uniformly dis
tributed load, because the base Of the
grider is so wide that it nearly covers
the clear span Of the stone, If this be
considered as beam spanning the
ilues. The stiffness Of the girder base
make 1t even quite permissible to
assume that the load would act on the
stone in sheer rather than bending.
But considering the worst case that
under the circumstances could exist,
that Of a beam with total load applied
as uniformly distributed, the caicula-
tions show that the sound stone has a
factor of safety of over 2 l.2.
The possibility of danger on the side
where the cracked Intel occurs must
be said to have been entirely removed
by inserting the inclined steel braces
l would recommend that similar
braces be placed on the opposite Cir
der as safeguard against possible dis
aSter in case Of unusual cyclonic
storms.
These bearing stones would have
been substituted by heavy grillage,
consisting OF four Is inch l beams GO
pounds spanning the tlues, with ample
bearings on the adjoining masonry,
which construction would have left
the entire structure beyond criticism.
NO SIGNS OF WEAKNESS.
Tile fact remains, however, that In
no place in this whole construction
are there any signs of weakness, not
one crack Of brlckwork or other ma,
sonry, no settlement or detection OF
any kind, and such would certainly
have appeared by this time, If weak
ness existed, especially to such degree
as was feared.
In conclusion beg to state that
the government need have no hes;;99s.:-
tion substituting the present ceiling
of lobby and the covering of the inner
dome by a permanent. fireproof and
suitable construction. provided the
weight Of same shall not exceed Is to
20 pounds per square foot. This can
be best obtained by light angle or "T''
iron framing covered by metal lathing
and hard plaster with the proper orn-
amental finish.
If such changes be contemplated
er brackets, supporting the inner
dome Oh the ribs of the main dome,
be first removed and replaced by SINH
lar but much longer brackets. 1t ap-
pears that one Of those main ribs is
cent, and think this Is due to the
fact that the bracket does not extend
far enough down on the steel rib.
The substitution Of such new brackets
can be accol. ished without much
difficulty, proper snoring being first
erected.
Attached to this report and forming
part of same are sketch showing lay
out OF the girders and five sheets Of
calculations.
Respectfully submitted,
(Signed) KoRT BERLE,
M. Am. Soc. G. e.,
Chief Structural Engineer,
Ofiice OF the Supervising Architect,
U. S. Treasury Department.
a Fatal Fall.