The Detroit times. [volume] (Detroit, Mich.) 1903-1920, 1911-02-20

and assist In the resistance 20 com
preston and shear.
mos Complete drawings, speci-
fieations and details or all rein
forced concrete construction. show
Ing the size and position or all re-
with the Department OF Buildings
before a permit TO construct such
work shall be issued. For all
buildings: strain sheets must be
The live loads in pounds per
? square foot for which the different
members are designed. shall be
marked on each and every moor
pis sec q 'n sE sraciDs OF 'S cahcnA
TON. In calculating the strength
OF reinforced and plain concrete.
used, for walls. columns, beams,
floor construction or for freproof-
only shall be used exclusive OF any
plastering or floor ballast
Reinforced concrete slabs. beams
and sirders. shall be designed In
accordance with the Following as
(a5 The accepted theory OF fiex-
ure shall be applied TO all mem
bers resisting bending.
(b) The steel shall take all the
(c) The ratio OF the modulus OF
elasticity OF concrete 20 that Of
steel shall be I to Is.
td) The modulus OF elasticity
shall remain constant at all work
Ie) The stress strain curve OF
concrete In compression shall be
considered az a straight line.
sT Sec S;sssss AL ,v,,.E,I UNIT
ing stresses. based on ngurins fun
live and dead loads, shall be used:
(a) The allowable unit stress
for plain steel bars shall not be
more than forty-five (46so) per cent
of the commercial elastic limit and
In no case greater than $4,000
pounds per square inch.
(b) Deformed high carbon steel
bars rolled from biilets shall not
be more than forty-five (4b%) per
cent OF the commercial elastic limit
and In no case greater than $4,000
pounds per square inch.
(c) All other steel reinforcing
bars rolled from billets which pro-
vide compound. tensile and sheer
members, shall not be more than
forty-nve 46%) per cent OF the
commercial elastic limit. and In no
case greater than 10000 pounds per
square inch.
(d) The allowable unit stress in
extreme fibre OF concrete In COM
preston, shall be six hundred and
nfty (66o) pounds per square inch.
(e) The allowable unit stress
upon concrete In direct compress.
nifty (i5oj pounds per square inch.
CD The allowable unit shear
Ing stress upon concrete shall be
forty GOD pounds per square inch.
,,rssg, The e, .a allowable Adhesive ss,,,
be forty t4o) pounds per square
inch.
Sec. s. COLUMNS. (a) For Col
umns reinforced with longitudinal
bars tied at intervals not greater
than twelve 12) times the least d.
ameter OF the bars. the safe load
shall be computed al follows:
16As).
Ac=net cross section Of columns
In square inches.
As=croas section OF longitudinal
reinforcement in square inches.
CD For columns reinforced with
longitudinal steel. and with spirally
wound hopping. provided. at least
one D per cent OF hopping ID used.
the safe load shall be computed as
Safe load I'm pounds)=sbo (Ac+
15As).
Ac=net cross section of concrete
enclosed In hopping.
As=net cross section Of longitudin-
Where columns are subject to loads
of known eccentricity. the combined
stresses In the extreme nbre 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 TO least side or
diameter does not exceed fifteen
Q5).
All columns shall have at least
one Q) per cent. OF longitudinal re-
enforcement, whether the same II
used In the calculations or not
Proper provision shall be made for
transmitting the stresses at the
splices In the column rods. and In
buildings over four 90 stories In
height. q 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 (lo) inches In Its
Sec. 8. BENDING MOMENTS
AND CONTINUOUS ACTION. The
bending moment for slabs and beams
with uniformly distributed load.
when not continuous over supports.
shall be taken at y WI.
When the slabs and beams are
continuous over both supports. the
bending moment for a 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 ell supports, the bend
ing moment OF the slab for a uni
isf al IA n
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. q. STEEL OVER SUP
PORTS. In all cases where reduc-
ton In the bending moment In 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
bending moment equal to the diff
ference between that allowed and
that given for non-continuous MEM
Sec. 8. BEAMS AND ORDERS
TO BE TREATED AS "T'' BEAMS.
IL the Orders. beams and slabs are
poured In one ~ continuous opera
ton. then the girders and beams
may be treated as IT. beams, with
portion OF the slab az nange. In
no case shall the nanse be OF
greater width than the distance be-
tween adjacent beams. or be as
sumed to extend 10 a distance on
each side OF the beam, greater than
three CD times the thickness OF the
slab.
In all cases where the shearing
stress along the plane OF junction
OF the rib and hange In excessive,
the beam must be reinforced by
means OF vertical or inclined steel
members crossing well the plane OF
Sec. .. STEEL IN COMPRESS
SION IN TRANSVERSE MEM
N Ne d 20 In