Experimental Determination of Eccentricity of Floor Loads Applied to a Bearing Wall

The eccentricity of the loads applied to a specially calibrated compressive strut simulating a brick bearing wall was experimentally determined for a variety of bearing materials and conditions of contact. In one series of tests, an I-beam was bedded in high strength gypsum plaster, bonded and unbonded. For the unbonded plaster bed the eccentricity ratio increased with the applied load to a maximum value of about 0.42, while for the bonded plaster bearing this ratio decreased to an average value of about 0.24 at the maximum load. In the second series of tests the eccentricity was observed for an I-beam supported on neoprene rubber pads, capped and uncapped, of different thicknesses, and of different bearing length. In general the eccentricity ratio increased slightly with the applied load. Lack of intimate contact between the I-beam and the rubber pad 1/8 in. thick resulted in an eccentricity ratio of about 0.40, or nearly the same as for unbonded plaster bearing. Intimacy of contact produced by plaster capping resulted in a marked reduction in the eccentricity ratio to about 0.29; the confinement of the bearing length of the rubber pad to one-half of that used in previous tests and placing it at the extreme end of the beam, further reduced the eccentricity ratio to about 0.18, and to 0.13 for a rubber pad 0.25 in. thick. (Author).