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

II tc) Ali other steel reinforcing
3 bars rolled from billets which pro-
% vide compound. tensile and sheer
II forty-iive C45qs) per cent OF the
% commercial elastic limit. and in no \
= case greater than 20. 600 pounds per
~ square irch.
Is (dJ The allowable unit stress I'm
~ extreme hbrc OF concrete I'm CONF
u preston, shall be six hundred and
y hfty ,Sao) pounds per square Inch.
~ to) The allowable unit stress
- upon concrete In direct compress.
u sion. shall be four hundred and
y nifty tsbo) pounds per square inch.
,s 90 The allowable unit shear
a Ing stress upon concrete shall bo
- forty t0) pounds per square inch.
"a ,g) The allowable adhesive
~ strength or concrete TO steel shall |
Is be forty t4o) 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 un pounds)=50o (Ac+
l5As).
Ac=net cross section of columns
~ In square inches.
II As=cross section OF longitudinal
u reinforcement In square inches.
IS (bl For columns reinforced with
"A longitudinal steel. and with spirally
10 WOunQ nOopiuk, pIoNiu~Os Ut lraSt
10 one Cd per cent OF hopping is used.
II the safe load shall be computed as
Is follows:
- Safe load dn pounds)=e6O (Ac-t
20 l6As).
Il Ac=net cross section OF concrete
y enclosed In hopping.
IS As=net cross section or longitudin-
- al reinforcement.
IS Where columns are subject to loads
20 or known eccentricity the combined
l- the AhrQ dine 10
,s direct compression and the bending
~ moment shall not exceed the maxi
30 mum compression stress allowed In
81 slabs and beams.
81 The above stresses apply only to
81 columns In which the ratio OF the
"a unsupported length to least side or
50 diameter does not exceed hfteen
30 05).
u All columns shall have at least
IS one % per cent. OF longitudinal re-
SO enforcement, whether the same IL
10 used In the calculations or not.
II Proper provision shall be made for
y transmitting the, stresses at the
"a buildings over four ca stories In
10 height. "A proper connection must be
Is made between the lower and the up
"a per ends OF the column rods
i8 In no case shall any column be
10 less than ten Qo) inches in its
so smallest dimension.
Sec 8. BENDING MOMENTS
AND CONTINUOUS ACTION. The
3 bending moment for slabs and beams
with a uniformly distributed load,
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 a uniformly dis
10 tributed load shall be taken at not
IL less than one-tenth WI
y Where slabs and beams are con-
% tinuous over one a. support only.
= the bending moment for a uniformly
10 distributed load. shall be taken at
u not less than ninth WI
u In the case OF square panels rein
Is forced in both directions and con-
- tinuous over all supports. the bend
10 ing moment OF the slab for a uni
Il formly distributed load shall be TAX
. e W. at not less ina" 0ne-'"e"''''"
a W=I.oad In pounds.
IS Length OF span In feet.
70 Length OF span shall always be
Z understood to be the clear distance
IS 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 introduced In the top OF the slab
Z 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. 8. BEAMS AND ORDERS
TO BE TREATED AS ''T'' BEAMS.
II the Orders. beams and slabs are
poured In one CD continuous opera
ton, then the Orders and beams
may be treated as ''T'' beams. with
no case shall the fange be of a
greater width than the distance be-
10 tween adjacent beams, or be as
II sumed to extend TO a distance on
-. H. ~ han Ia ~
l3 three 90 times the thickness OF the
4 slab.
IS In all cases where the shearing
10 stress along the plane OF junction
Il OF the rib and fiange Is excessive,
q the beam must be reinforced by
- means OF vertical or inclined steel
70 members crossing well the plane OF
Sec. .. STEEL IN COMPRESS
SION In TRANsvERsE MEM
BEERS. Where II is necessary to in
troduce steel to resist compression
in Orders. beams or slabs. the com.
pressive stress allowed on such steel
shall not exceed fifteen U5) times
= the computed compressive stress In
the concrete at the same distance
10 from the neutral axis
ii Such steel must be thoroughly
- anchored into the mass OF the con-
10 crete b. means OF stirrups or other
Il wise to prevent any possibility OF
& buckling
Sec. 10. sHRINKAGE AND
THERMAL STRESSES. Shrinkage
and thermal stresses shall be pro-
vided for by the introduction OF
steel.
Sec. II. EXCESSIVE SHEAR
When the Ehearing stresses devel- |
oped In any part OF reinforced
concrete structure. exceed under the
combined loads the allowed shear
ing stress as fixed horein. a sufii |
Client amount OF steel shall be intro |
duced I'm such a position that the
deficiency In resistance TO Shear is
Sec. i2. COLUMNS FILLED
2 WITH CONCRETE. Columns built
up OF structural steel shapes, Sc
curely latticed together by rivetting
and filled In solid and surrounded
with concrete, may be figured as
: reinforced concrete columns using
stress OF eight hundred $500
pounds per square inch on the en-
u closed concrete and twelve thousand
1 Qe00o) pounds per square inch on
2 steel Where reinforced concrete
. beams frame into such columns, the
entire end shear shall be taken by
8 steel brackets OF by concrete brack-
C cts. properly reinforced. and con-
= nected TO concrete core Of columns.
IS and moulded simultaneously with
Sec. is. PROPORTIONS OF IN
GRADIENTS. The concrete for
walls. beams. grders and floor con-
struction, shall be mixed i'm proper
ton by volume. OF one Cd part Port
land cement to two 60 parts OF sand
and not more than four ca parts OF
either broken stone or gravel.
The concrete for columns. shall be
10 mixed I'm the proportion or one Cd
4 part Portland cement, one and one
g half Oia) parts OF sand and three
I3 90 parts OF broken stone or gravel. |
IA In no case shall more than two GU
8 parts Of sand be used to enc Q) part
g of cement.
II All mixing shall be done by machine !
Is II the total amount OF concrete ex- |