26 BULLETIJ?^ 1259, U. S. DEPARTMEXT OF AGEICTJLTURE. 
SECTTION 4. DISTRIBUTION OF LOADS. 
DISTRIBTJTIOX OF TRUCK WHEEL LOADS TO STRINGERS 
AND FLOOR BEAMS. 
1. Shear. In Calculating end shears and end reactions of stringers 
and floor beams, no lateral or longitudinal distribution of 
wheel loads shall be assumed. 
2. Bending mo- In determining bending moments in stringers, each 
ment m stringers, .^-j^^^-^ load shall be assumed as concentrated at a point. 
When the floor system is designed for one truck, each 
interior stringer shall be proportioned to support that 
part of one rear wheel load, or those parts of one front 
wheel load and one rear wheel load, represented by a 
fraction whose numerator is the stringer spacing in feet 
and whose denominator is : 
4 feet for plank floors. 
5 feet for strip floors 4 inches or more in thickness and for 
wood blocks on a 4-inch plank siibfloor. 
6 feet for reinforced concrete floors. 
When the floor system is designed for two trucks, each 
interior stringer shall be proportioned to sunport that 
part of one rear wheel load, or those parts of one front 
wheel load and one rear wheel load, represented by a 
fraction whose numerator is the stringer spacing in feet 
and whose denominator is : 
33^ feet for plank floors. 
4 feet for strip floors 4 inches or more in thickness and for 
wood blocks on 4-inch plank siibfloor. 
43^ feet for reinforced concrete floors. 
The live load supported by the outside stringers shaU 
be the reaction of the truck wheels in the most unfavor- 
able position, assuming the flooring to act as a simple 
beam, but this live load shall in no case be less than would 
be required for interior stringers under the above require- 
ments. 
The above distribution rules govern only when the 
stringer spacing is not greater than the denominator 
which applies to the particular case under consideration. 
When the stringer spacing is greater than this distance 
the stringer loads shall be determined by the reactions of 
the truck wheels placed in the most unfavorable position, 
assuming the flooring between stringers to act as simple 
beams. 
The combined load capacity of the stringers in a panel 
shall be not less than the total live and dead load in the 
panel. 
3. Bending mo- In determining bending moments in floor beams, each 
^ms ^° ^°^'' wheel load shall be assumed as concentrated at a point. 
Wlien stringers are omitted and the floor is supported 
directly on the floor beams, tlie latter shall be proportioned 
to carry that fraction of one axle load, when the floor 
system is designed for one truck, or of two axle loads, 
when the floor system is designed for two trucks, whose 
numerator is the floor beam spacing in feet and whose 
denominator is : 
