The bearing strength of concrete loaded through flexible plates

Approximate expressions are developed for the bearing strength of concrete axially loaded by a punch covering a limited area of the bearing plate. Depending on their stiffnesses, plates are characterized as flexible, semi-flexible or rigid. It is shown that for a flexible plate the ultimate capacity increases linearly with the plate thickness, whereas for a semi-flexible plate the rate of increase rises continuously until a maximum value is reached corresponding to the capacity for a rigid plate. The expressions predict the results for eight series of tests on concrete blocks loaded through plates ranging in thickness from 1/32 in. to 1 in.