consequently the double-bend rods of the girder under design should lap over to the third-point instead of stopping at the quarter-point of the adjacent. span, as they would if the two members were each fully-continuous.

In the lower part of the girder, over the interior support, the straight rods must have sufficient anchorage to resist the positive bending moment, and also to develop compressive strength as an aid to the concrete. Since the unit compressive stress in the steel may approximate

the required length of embedment is, by Formula (16), Chapter IV,

=

(4)(fs/u)i

=

(4) × (11 250/100) × 0.875

= 24.5 in

in which 0.875 is the diameter of a %-in rod, and 100 the allowable unit bondstress for deformed rods, in pounds per square inch.

(10) The reinforcement at the bottom of the girder is therefore lapped 2 ft 0 in beyond the further face of supports. This arrangement results, also, in an embedment more than sufficient to resist the stresses due to positive bending moments.

12. Tables of Reinforced-Concrete Slabs. Tables III to XI give the sizes of reinforcing rods and bars for slabs of different spans, thickness, and continuity; and for different uniformly distributed loads.

Table III.* Data for Design of Reinforced-Concrete Slabs, Carrying a Live Load of 40 Pounds per Square Foot

*This table is based on a minimum slab-thickness of 3% in for roofs and 4 in for floors as per the New York City Code. The dead load includes only the weight of the concrete slab, of the thickness shown, except as noted, for roofs.

Table IV.* Data for Design of Reinforced-Concrete Slabs, Carrying a Live Load of 50 Pounds per Square Foot

*This table is based on a minimum slab-thickness of 31⁄2 in for roofs and 4 in for floors as per the New York City Code. The dead load includes only the weight of the concrete slab, of the thickness shown, except as noted, for roofs.

Table V.* Data for Design of Reinforced-Concrete Slabs, Carrying a Live Load
of 75 Pounds per Square Foot

fe 16 000 lb per sq in

Dead load includes 3 lb per sq ft for roofing Steel-values inclosed in parenthesis are not economical sizes

SLAB-STEEL

M==

semicontinuous
simple

clear span, in feet

(LĮ plus slab-thickness), in inches
unit dead and live load, per square foot
effective depth (slab-thickness minus
1 in), in inches

bending moment for slabs 1 ft wide, in
inch-pounds

(wL) L

12

for continuous slabs, in inch

pounds

(wL1) L

10

inch-pounds

(w L1) L
8

for semicontinuous slabs, in

for simple slabs, in inch-pounds

*This table is based on a minimum slab-thickness of 31⁄2 in for roofs and 4 in for floors as per the New York City Code. The dead load includes only the weight of the concrete slab, of the thickness shown, except as noted, for roofs.

Table VI.* Data for Design of Reinforced-Concrete Slabs, Carrying a Live Load of 100 Pounds per Square Foot

650 lb per sq in

fe 16 000 lb per sq in

Steel-values inclosed in parenthesis are not

economical sizes

M =

simple

clear span, in feet

(L plus slab-thickness), in inches
unit dead and live load, per square foot
effective depth (slab-thickness minus
1 in), in inches

bending moment for slabs 1 ft wide, in
inch-pounds

(wL) L

for continuous slabs, in inch

12 pounds (wLy) L

10

for semicontinuous slabs, in

inch-pounds
(wL) L
8

for simple slabs, in inch-pounds

*This table is based on a minimum slab-thickness of 31⁄2 in for roofs and 4 in for floors as per the New York City Code. The dead load includes only the weight of the concrete slab, of the thickness shown, except as noted, for roofs.