Base Plates Under Axial Loads and Moments

Experiments are conducted to study the behavior of base plates under the action of axial loads and moments by eccentric loading on the column. The parameters in the study are the thickness of the base plate and the eccentricity of the load. At the lowest eccentricity, failure was by cracking of the concrete, while at other eccentricities the primary mode of failure was by the yielding of the base plate. Comparisons of the test results with the predictions from the Working Stress Method gave a range of 1.09–1.89 for the factor of safety with a mean value of 1.35 for specimens that failed by yielding of the base plate. The strain distributions in the base plate were obtained at various stages of loading. They indicate the existence of a critical section of maximum strain, a section of zero strain and strain reversal. The eccentricity of the load seems to have a greater influence on the strains than the thickness of the base plate. The test results show that flexible base plates when loaded at high eccentricities fail primarily by yielding of the plate and that their behavior is somewhat different to that predicted by the present design methods.