The Detroit times., 1911-02-23

TERM The term reinforced con
crete" shall be understood 10 mean
An approved concrete mixture, re-
inforccd by. steel or iron OF any
shape. 80 that the steel and iron
will take up all tension stresses.
and assist In the resistance 20 com
preston and shear.
Sec. 2. PERMITS, AND DRAW
INCiS. Complete drawings. apecl-
fieations and details OF all rein
forced concrete construction. show
ingFthe Size and position OF all re-
inforcing members. shall be hled
with the Department OF Buildings
work shalt be issued, For all
buildings. strain sheets must be
submitted with the drawings and
specifications
square foot for which the different
members are designed. shall be
marked on each and every moor
plan OF the Drawings submitted.
Sec. 3. METHOD OF CALcULk-
TON. In calculating the strength
used for wallis, columns, beams,
floor construction or for hreproof-
ing. the thickness OF the concrete
only shall he used exclusive of any
pisstering OF floor ballast.
Reinforced concrete slabs. beams
and sirders. shall be designed In
accordance with the following as
SYMPTOMS:
ure shall be applied TO all mem
bers resisting bending.
tb) The steel shall take all the
tension stresses.
.te) The ratio OF the modulus of
elsstictty. OF concrete TO that Of
steel shall be to 10.
td) The modulus OF elasticity
shall remain constant at all work
ing stresses.
(e| The stress strain curve OF
eeo one,rSsts n comprs sssS shah be
sTREssEss. The foIl os WORK york.
ing stresses. based on figuring full
live and dead loads, shall be used:
,oSSp The ailowabie unit stress s
more than forty-flve (457s) per cent
or the commercial elastic limit and
in no case greater than 10000
pounds per square inch.
bars rolled from biiiets shall not
be more than forty-five (45ss) per
cent or the commercial elastic limit
and In no case greater than $4,000
po seS Per o square . inch r.,n,or,,n.
bars rolled from biiiets which pro-
vide compound, tensile and sheer
members. shall not be more than
forty-flve (46S6) per cent OF the
commercial elastic limit. and in no
case greater than 10000 pounds per
(d) The allowable unit stress I'm
extreme fibre OF concrete in COM
preston, shall be six hundred and
nfty tS50) pounds per square inch.
upon concrete In direct compress
sion. shall be four hundred and
nrty ttbo) pounds per square inch.
O The allowable unit shear
ing stress upon concrete shall be
forty l40) pounds per square inch.
tg) The allowable adhesive
strength OF concrete to steel shall
be forty t4) pounds per square
Sec. s. COLUMNS. "a, For Col
umns reinforced with longitudinal
bars tied at intervals not greater
than twelve U2) times the least d.
ameter OF the bars, the safe load
shall be computed az follows:
Safe load Tin pounds)=5o0 (Ac+
Ae-net cross section Of columns
As=-croe section OF longitudinal
reinforcement In square inches.
(b) For columns reinforced with
longitudinal steel, and with spirally
wound hopping. provided. at least
one % per cent OF hopping Is used.
Safe load lin pounds)=s5o CAc+
15As).
Ac==net cross section OF concrete
enclosed In hopping.
As=net cross section OF iongftudin-
nj reinforcement
Where columns are subject TO loads
OF known eccentricity. the combined
stresses In the extreme fibre due to
direct compression and the bending
moment shall not exceed the maxi
mum compression stress allowed In
slabs and beams.
The above stresses apply only to
columns In which the ratio OF the
unsupported length 20 least side or
diameter does not exceed fifteen
All columns shall have at least
enforcement. whether the same, Is
used In the calcula tons or not.
Proper provision shall be made for
transmitting the stresses at the
spices I'm the column rods, and In
buildings over four az 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 uo) inches In its
smallest dimension s
Sec. 8. BENDING MOMENTS
AND CONTINUOUS ACTION. The
bending moment for slabs and beams
when not continuous over supports,
shall be taken at u WI.
When the slabs and beams are
continuous over both supports. the
bending moment for n uniformly dis
tributed load shall be taken at not
less than one-tenth WI.
Where slabs and beams are con-
tlnuous over one ID 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 uni
formly distributed load shall be TAX
en- at not less than one-twentieth
w=Load In pounds
Length OF span in feet.
Length OF span shall always, be
understood 10 be the clear distance
between the supports.
Sec. z. steel OVER SUP
PORTS. In all cases where reduc-
ton In the bending moment Is al
lowed on account OF the continuous
action, sufficient reinforcement must
be Introduces in the top OF the slab
or beam over the supports. to take
bending moment equal to the diff
ference between that allowed and
that given for non-continuous mem
bers.
Sec. q. BEAMS AND ORDERS
TO BE TREATED AS "T' BEAMS.
II the girders, beams and slabs are
poured In one az continuous opera
ton. then the girders and beams
may be treated as EFT" beams. with
a portion OF the slab as n flange. In
no case shall the flange be OF
Vreatar width than tha distance he
tween adjacent beams, or be as
- sumed TO extend to distance on
each side OF the beam. greater than
three (3) times the thickness OF the
slab.
In all cases where the shearlng
stress along the plane OF junction
OF the rib and hange n excessive,
the beam must he reinforced by