The Detroit times. [volume] (Detroit, Mich.) 1903-1920, 1913-10-22

~ entirely fixed at a point OF sups
v port. but Is not regarded As con-
. as much steel shall be provided at
. the top over the support AS AT
4 the center.
8 te) Beams or slabs supported
q partly or entirely by cantilever
z action at the supports other than
8 those herein especially mentioned
- may be used provided that the
% negative and positive bending
4 moments taken together are not
3 less than the bending moment FOR
q non-continuous members and that
4 proper allowance Is made Tor
% bending moments In coiumns ana
10 torsional moments In girders
II arising from unequal loading OF
such structures and provided tnat
~ the total shear and compression
20 due TO combined shear and com
u preston in concrete does not eN
y coed the allowed value. When
'3 such special cantilever construc-
a tions are used the point OF In
IS hexion assumed shall be clearly
20 marked, labeled and dimensioned
~ I'm at least one typical case on
IS each sheet Of drawings.
Sec. I. Flat slab floors. tD
Girderless HAT slab floors rein
forced In either two or four
directions and supported py en-
larged column capitals may 9e
5 constructed according to the toi-
W-total dead and live load per
. square foot.
~ Length OF one side OF panel
IL IL square or IL rectangular IL Is
l. the larger dimension measured
Is from center TO center of columns.
Il B-shorter dimension or rect
10 angular panel measured from
l6 center OF columns.
IL L. side OF square having same
Is diagonal as rectangle Is l. or In
10 square panel II equals L.
2o D-diameter OF column capitaI
81 at "a point where II Is az least one
22 and one half 1h inches thick
% K--bending moment coefhcient
"a having the values hereinafter de-
20 fined.
90 ID must not be less than 225 l.
q and the sides OF the column capi-
2s tai must not slope at an angie
20 with the perpendicular of more
30 than forty-hve degrees. provided
81 that II the slab lis increased in
80 diameter OF the capital may be
81 reduced by one and one-halt
81 lhD times the thickness or
80 such drop
80 tb) Slabs reinforced in four Cd
81 directions. The steel In the cen.
40 ter OF the panel shall he designed
IL to resist bending moment or
~ one twenty fifth u-25) Wl-3 for
AZ interior and one twenty second
~ I-22 WIS for exterior panels.
as The steel so determined shall be
IS divided equally among two aiag-
IS square panels and in the case OF
~ rectangular panels one-half OF
80 this steel shall he equally divided
81 between the diagonal bands ana
50 the remainder between the cross
IS bands in proportions TO the cubes
81 of their lengths.
SIS The negative bending moment
So in $50 degrees around the column
81 capital. that is the negative mo,
So ment resisted by two diagonal
50 and two cross bands at the sup
81 ports shall be taken as one
81 fifteenth W1-3.
So To compute the concrete stress
63 at the column capital "A negative
81 bending moment OF one-twenty-
So fifth WI shall be assumed to be
SIS resisted by a band OF concrete not
81 wider than ID plus six times the
IS slab thickness. nor wider than
So the sunken panel or drop II sucn
20 is used, nor wider than 4 L.
II (c) Slabs reinforced In two tD
72 directions only. The bending
"a be calculated by dividing the slab
rs into eight 90 equal strips start
rs ing from the center line of two
II columns Each strip shall be re-
rs garded as continuous beam hav-
10 Ing positive bending moment at
50 the center and negative bend
81 ing moment at the line OF sup
So ports. The bending moment at
90 each OF these points shall be WI
IS els and for rectangular panels
S. VII BIS X in the direction OF l..
81 and W B 2 LIS X I'm the direction
IS OF b. The values OF X shall be
50 taken for interior panels az foi-
90 lows. starting at the center line
81 At line OF supports. At center.
% First strip Ia --s5ss
s5 Third and
Us fourth strips
~ each SIS -i-3S
~ For exterior panels these values
% t20%), Compressive stresses In
Oh concrete are to be calculated by
% assuming that the entire width
% Of each strip resists the bending
~ moment assigned to II.
% td) Alternative method for
Do two way reinforcement. III de-
OF sired that portion OF the slab
% lying between column capitals
% may be regarded as continuous
10 girder and the central portion OF
IL the plate as a slab reinforced in
IL two ways and supported on all
l3 four sides.
is yirder shall not be wider than
l6 the column capital plus six go
IL times the thickness OF the slao
Is nor wider than % l..
10 The negative bending moment
20 at the support and the positive
22 shall each be taken as WI 2-24
% where Is the clear span In the
"a direction OF the girder and Is
Is the distance between column GEN.
Is ters at right angles TO the girder.
~ The remainder OF the slab shall
28 be known as the inclosed panel
20 and shall be bounded by lines
30 parallel to lines Of center OF
"a a
80 the edge OF column capitals not
81 greater than two and one-half
"a times the thickness Of the slab.
e edrs Of 9e the inclos Sen panel shall
81 be taken as W ga and at the
IS center as w 3--36 In each direc-
80 ton where p Is the side OF the
20 square for square panels and Ia
y the side OF an equivalent square
~ for rectangular panels.
IS (e) No fiat slab shall have
~ thickness at the center OF less
is than. one thirty-second 1-s2(
rs for floors nor less than one thir-
IL ty-ffth n-s5) ] for. roofs.
IS (o When the slab near the
10 column capital IL increased I'm
% thickness so as to form a sunk Ken
q dimensions Of this drop shall be
IL not less than .s75 times the panel
"a length In the same direction.
Sec. .. Beams and girders TO
q be treated as II beams III the
3 girders, beams and slabs are
poured In one "a continuous OPP
Grafton. then the Orders and
s beams may be treated as "T''
beams, with q portion of the slab
3 as hange. $50
. In no case shall the fange be
10 Of a greater width than the dis
II lance between adjacent beams.
Il nor greater than one fourth tA)
70 OF the clear span nor be assum-
IA ed to extend to distance on
Is each side OF the beam greater
IS than five go times the thickness
Il of the slab.
is In all cases where the shear
ID Ing stress along the plane OF
10 junction OF the rib and hange Is