TESTS OF A LARGE-SIZED REINFORCED-CONCRETE 
SLAB SUBJECTED TO ECCENTRIC CONCENTRATED 
LOADS 
By A. T. Goldbeck, Engineer of Tests , and H. S. Fairbank, Highway Engineer , 
Office of Public Roads and Rural Engineering, United States Department of Agriculture 
INTRODUCTION 
During the past five years a series of tests to determine the distribution 
of stress in reinforced-concrete slabs carrying concentrated loads has 
been made by the Office of Public Roads and Rural Engineering. The 
slabs included in the series have varied from 3 to 16 feet in span, and 
6 to 32 feet in width; and as a result of the tests much information has 
been collected, practically all of which has been published at various 
times. 1 (1, 2, 3, 4, 6.) 1 
In all of these tests the concentrated load has been applied to the 
center of the slab, and sufficient data have been gathered to indicate 
the manner and extent of stress distribution in slabs loaded in this 
manner. In general, it may be said that the stress varies from a maxi¬ 
mum immediately under the load to a minimum at the extreme edges. 
The information as to the extent of the distribution has been made avail¬ 
able for use in the rectangular-beam theory of design by the determina¬ 
tion of a value known as the “effective width,” which, when substituted 
for the width b in the formulas, will lead to the design of slabs of dimen¬ 
sions conforming to those shown by the tests to be necessary. This * 
value is represented by that width of slab over which, if the stress were 
constant and equal to the maximum stress under actual conditions, the 
resisting moment would equal the resisting moment of a slab of the same 
depth and full width in which the stress is naturally distributed. It has 
been brought out in the previous papers that this effective width varies 
with the total width and span, the relation being approximately as 
expressed in the table following. 
1 Gold beck, A. T. tests of reinforced concrete slabs under concentrated loading. In Amer. 
Soc. Testing Materials, Proc., v. 13, p. 858-873,10 fig. 1913. 
-THE INFLUENCE of TOTAL WIDTH ON THE EFFECTIVE WIDTH OF REINFORCED-CONCRETE SLABS 
subjected To central concentrated loading. In Amer. Concrete Inst., Proc. v. 13, p. 78-88, 13 fig. 
1917. 
- and Smith, E- B. tests of large reinforced concrete slabs. In Amer. Concrete Inst. 
Proc., v. 12, p. 324-333. 1 fig- 1916. 
-TESTS OF THREE LARGE-SIZED REINFORCED-CONCRETE SLABS UNDER CONCENTRATED LOAD¬ 
ING. In Jour. Agr. Research, v. 6, no. 6, p. 205-234, 28 fig., pi. 26. 1916. 
McCormick, E. B. test of a reinforced concrete slab. In Amer. Concrete Inst. Proc., v. n, p. 
195-204, 8 fig. Discussion, p. 202-204. 1915- 
( 5 °S) 
Journal of Agricultural Research, 
Washington, D. C. 
ks 
Vol. XI, No. 10 
Dec. 3, 1917 
Key No. D—15 
