ABSTRACT
Dynamic loads on step ladders are the result of interaction between climber and ladder. The complex dynamical behavior of the climber must be experimentally determined. An analysis of the dynamical response is presented to allow the extrapolation of experimental results to ladders of grossly different structural dynamical parameters from those on which the data are obtained. It is demonstrated that the climber characteristics dominate the dynamical response. Reliable quantitative measures of data applicability are obtained, not withstanding significant uncertainties regarding the details of the mechanics of motion. The results of the dynamical analysis are combined with published experimental observations of dynamical loads to predict the range of anticipated loads to the bottom step of a wood step ladder which was the subject of a products liability suit. The particular step was known to be severely cross-grained near the center of the span. Described herein are the results of an analysis of the effect of the material defect on the strength of the step, a stress analysis of the rod-reinforced step, and an analysis of the post-fracture deformation of the structure.
