The Detroit times. [volume] (Detroit, Mich.) 1903-1920, 1910-12-07

9 pounds per square inch.
te) All other steel reinforcing
$ bars rolled from billets which pro-
. vide compound. tensile and sheer
y members. shall not be more than
forty-nve 45qtD per cent OF the
. commercial elastic limit. and In no
3 ease greater than 10000 pounds per
4 square irch.
3 Cd The allowable unit stress In
6 extreme fibre OF concrete I'm COM
! preston. shall be six hundred and
: mtg t6ho) pounds per square Inch.
= 'c) The allowable unit stress
. upon concrete In direct compress.
| sion. shall be four hundred and
: nifty ti5O) pounds per square inch.
. 90 The allowable unit shear
J forty 6iO) pounds per square inch,
G lg) THE allowable adhesive
strength or concrete To steel shall
\ be forty (io) pounds per square
. inch.
See. 6. COLUMNS. (a) For Col
? unns reinforced with longitudinal
z bars tied at intervals not greater
4 than twelve n2l times the least d.
8 ametef OF the bars. the safe load
u snail be computed as follows:
: Safe load dn poundsJ=5oo tAc-f
) has.
. Ac=net cross section OF columns
U In square inches.
l As=cross section OF longitudinal
2 reinforcement In square inches.
3 (b) For columns reinforced with
I longitudinal steel. and with spirally
6 wound hopping. provided. at least
4 one l per cent OF hopping Is used.
Z the safe load shall be computed az
3 follows:
. Safe load Din pounds)=e50 (Act
o l6As).
| Ac=net cross section OF concrete
2 enclosed In hopping.
3 As-=net cross section OF longitudin-
4 al reinforcement
r,fa,x tk.tn tn n n Ia
9 OF known eccentricity the combined
7 stresses In the extreme fibre due 70
\ direct compression and the bending
. moment shall not exceed the maxi
o mum compression stress allowed In
slabs and beams.
2 The above stresses apply only to
3 columns In which the ratio OF the
4 unsupported length TO least side or
8 diameter does not exceed fifteen
8 N5).
7 All columns shall have at least
one % per cent. Of longitudinal re-
3 enforcement, whether the same IL
0 used In the calculations or not
l Proper provision shall be made for
2 transmitting the stresses at the
3 splices in the column rods. and in
buildings over four ca stories In
8 height. proper connection must be
8 made between the lower and the up
per ends OF the column rods.
8 In no case shall any column be
leSS IMAM Ten wv lnCneb III its
o smallest dimension.
Sec. 8. BENDING MOMENTS
2 AND CONTINUOUS ACTION The
bending moment for slabs and beams
with Il uniformly distributed load,
: when not continuous oyer supports.
u shall be taken at u WI.
Z When the slabs and beams are
y continuous over both supports. the
3 bending moment for uniformly dis
0 tributed load shall be taken at not
less than one-tenth WI.
2 Where slabs and beams are con-
3 tinuous over one "a support only,
4 the bending moment for a uniformly
D distributed load. shall be taken at
. not less than one-ninth WI.
I In the case Of square panels, rein
) forced In both directions and con-
9 tinuous over all supports. the bend
o ing moment OF the slab for uni
| formly distributed load shall be TAX
3 WI.
4 W=Load In pounds.
b Length OF span In feet
8 Length OF span shall always be
I understood to be the clear distance
s between the supports
Sec. T. STEEL OVER SUP
2 PORTS In all cases where reduG-
3 ton In the bending moment Is al
4 lowed on account OF the continuous
8 action. sufficient reinforcement must
8 be introduced In the top Of the slab
Z or beam over the supports, TO take
) a bending moment equal to the diff
8 ference between that allowed and
o that given for non-continuous mem
4 bers.
Sec. 8. BEAMS AND ORDERS
. TO BE TREATED Az ct" BEAMS.
3 II the sirders. beams and slabs are
4 poured in one Q continuous opera
s ton. then the Orders and beams
Il may be treated as "T'' beams. with
I a portion of the slab as hange. In
3 no case shall the flange be Of u
. greater width than the distance be-
o tween adjacent beams. or be as
| sumed TO extend to a distance on
. each side OF the beam. greater than
3 three 90 times the thickness OF the
4 slab.
. In all cases where the shearing
G stress along the plane OF junction
! OF the rib and fange Is excessive.
< the beam must be reinforced by
. means OF vertical or inclined steel
Sec. .. STEEL IN COMPRESS
, SION IN TRANSVERSE MEM
3 BERS. Where It is necessary to In
4 troduce steel 10 resist compression
8 in girders, beams or slabs. the com
G pressive stress allowed on such steel
: shall not exceed fifteen Q5) times
s the computed compressive stress In
o the concrete at the same distance
q from the neutral axis.
l Such steel must be thoroughly
= anchored into the mass OF the con-
9 crete by means OF stirrups or other
wise to prevent any possibility OF
: buckling
Sec. 10. SHRINKAGE AND
{: THERMAL STRESSES. Shrinkage
3 and thermal stresses shall be pro-
4 yided for by the introduction OF
) steel.
Sec. Ii. EXCESSIVE SHEAR
? When the ghearing stresses devel-
3 oped In any part OF a reinforced
4 concrete structure. exceed under the
. combined loads. the allowed shear
d ing stress as fixed herein. a sufii-
I cient amount OF steel shall be intro
y duced I'm such position that the
y deficiency In resistance to shear is
D overcome.
9 WITH CONCRETE. columns built
2 up OF structural steel shapes. Sc
4 curely latticed together by rlvetting
4 and filed In sclid and surrounded
8 with concrete, may be figured as
I reinforced concrete columns. using
4 stress OF eight hundred 5000
y pounds per square inch on the en-
u closed concrete and twelve thousand
az ,000) pounds per square inch on
. steel Where reinforced concrete
; beams frame into such columns. the
4 entire end shear shall be taken by
) steel brackets or by concrete brack-
6 cts. properly reinforced, and con-
: nectcd to concrete core OF columns.
s and moulded simultaneously with
y columns.
Sec 49, PROPORTIONS OF IN
2 GRADIENTS. The concrete for
, walls, beams, girders and floor con-
4 struction. shall be mixed In proper
8 ton by volume. OF one % part Port
q land cement to two 90 parts OF sand
: and not more than four ca parts OF
d either broken stone or gravel
. The concrete for columns. shall be
y mixed i'm the proportion OF one Oh
part Portland cement one and one
. half Ula) parts OF sand and three
3 90 parts OF broken stone or gravel.
4 In no case shall more than two t2l
: marta ~ sand ha used IN one IN mart