The Detroit times., 1911-02-23

lnLOICtu Ul UlNIL OF lIOn OF any
shape, 80 that the steel and iron
Will take up all tension stresses.
aud assist In the resistance 10 COM
precision and shear.
Sec. 2. PERMITS AND DRAW
INGS. Complete drawings, speci-
fcations and details OF all rein
forced concrete construction. show
ing the size and position OF all re-
inforcing members. shall be filed
with the Department OF Buildings
before a permit 70 construct such
work shall be issued. For all
buildings, strain sheets must be
submitted with the drawings and
specifications.
The live loads IN pounds per
square foot for which the different
marked on each and every floor
plan of the drawings submitted
Sec. 3. METHOD OF CALCULA-
TON. In calculating the strength
OF reinforced and plain concrete.
floor construction or for nreproof-
Ing, the thickness OF the concrete
only shall be used exclusive or any
plasterlng or moor ballast.
Reinforced concrete slabs, beams
and sirders. shall be designed I'm
accordance with the following as
Gas The accepted theory of nex-
ure shall be applied to all mem
bers resisting bending.
(b) The steel shall take all the
tension stresses.
(c) The ratio OF the modulus OF
elasticity of concrete 10 that OF
steel shall be to 10.
I'D The modulus OF elasticity
shall remain constant at all work.
ing stresses.
(e) The stress strain curve OF
concrete In compression shall be
e0 ssee as AL ffso5Saghs lans' UNIT
STRESSES The following work
ing stresses, based on figuring full
live and dead loads. shall be used:
(a) The allowable unit stress
more than forty-five (45s5) per cent
of the commercial elastic limit and
In no case greater than 10000
pounds per square inch
bars rolled from billets shall not
be more than forty-five (45go) per
cent or the commercial elastic limit
ana In no case greater than $4,000
po ssS Per o square Inc inch .,,,o..,,
bars rolled from biilets which pro-
vide compound. tensile and sheer
members, shall not be more than
forty-hve (45So) per cent OF the
commercial elastic limit, and I'm no
case greater than 10000 pounds per
(d) The allowable unit stress in
extreme fibre OF concrete in COM
preston. shall be six hundred and
nits oSS Tbs pounds a1,nn Per square SOUS, inch;
upon concrete In direct compress
sion, shall be four hundred and
NIFTY (460) pounds per square inch.
% The allowable unit shear
forty ilo) pounds per square inch.
lG The allowable adhesive
strength or concrete TO steel shall
be forty t4D pounds per square
Sec. s. COLUMNS. (a) For Col
umns reinforced with longitudinal
bars tied at intervals not greater
than twelve Q2) times the least d.
ameter OF the bars. the safe load
shall be computed as follows:
Safe load Tin pounds)=soo (Ac+
Ac=net GROSS section of columns
In square inches.
As=cross section OF longitudinal
reinforcement In square inches.
(b) For columns reinforced with
longitudinal steel. and with spirally
one tD per cent OF hopping is used.
the safe load shall be computed as
follows:
Safe load dn pounds)=s6o (Act
15As).
Ac=net cross section OF concrete
NheAoocu III noOpiHk.
As=net cross section Of longitudin-
al reinforcement.
Where columns are subject TO loads
or known eccentricity. the combined
stresses In the extreme fibre due to
direct compression and the bending
mum compression stress allowed In
slabs and beams
The above stresses apply only to
columns In which the ratio OF the
unsupported length to least side or
Q5).
All columns shall have at least
one O per cent OF longitudinal re-
enforcement. whether the same In
used In the calculations or not.
Proper provision shall be made for
transmitting the stresses at the
spices In the column rods. and In
buildings over four 90 stories In
height, proper connection must be
made between the lower and the up
per ends OF the column rods.
In no case shall any column be
less than ten (10) inches In its
Sec. 9. BENDING MOMENTS
AND CONTINUOUS ACTION. The
bending moment for slabs and beams
with a uniformly distributed load.
when not continuous over supports,
shall be taken at V WI.
Wuen the slaps ana beams are
continuous over both supports. the
bending moment for uniformly dis
tributed load shall be taken at not
less than one-tenth WI.
Where slabs and beams are con-
tinuous over one ~ support only.
the bending moment for a uniformly
distributed load. shall be taken at
not less than one-ninth WI.
In the case OF square panels, rein
forced in both directions and con-
tinuous over all supports, the bend
ing moment of the slab for a uni
formly distributed load shall be taxi
WI.
w=Load In pounds.
Length of span In feet
Length OF span shall always be
understood to be the clear distance
between the supports.
Sec. z. STEEL OVER SUP
ton In the bending moment Is al
lowed on account OF the continuous
action, sufficient reinforcement must
be introduced In the top OF the slab
or beam over the supports. TO take
a bending moment equal to the diff
ference between that allowed and
that given for non-continuous MEM
bers
Sec. 8. BEAMS AND ORDERS
TO BE TREATED AS "T' BEAMS.
IL the girders. beams and slabs are
poured In one u) continuous opera
ton. then the girders and beams
may be treated as ''T'' beams, with
a portion OF the slab as a fange. In
no case shall the flange be OF a
greater width than the distance be-
tween adjacent beams, or be as
sumed to extend TO distance on
each side OF the beam, greater than
three (D times the thickness OF the
slab.
In all cases where the shearing
stress along the plane or junction
OF the rib and fange n excessive.
the beam must be reinforced by
means of vertical or inclined steel
members crossing well the plane OF
Sec. .. STEEL IN COMPRESS