The initial step in dimension cargo-bearing frames is the
determination of loadings. The goal of such dimensioning is to
prevent a structural failure during the service-life. The
time-dependent loading of cargo in vehicles can be represented by a
discontinuous, stochastic, low-frequency process. For analytical
purposes, these loadings are approximated by bounded frequency
functions from which loading factors and distribution values can be
derived.
Examples of different vehicle types are given and the
periodicity of their loadings are shown. From this data, three
different types of loading distributions are seen: approximately
symmetrical, a combined symmetrical distribution with a
superimposed frequency function, and strongly assymetrical. An
analysis of peak values of loading leads to an evaluation of
probability of structural failure. These peak values are shown to
be caused not only by heavy cargo, but also by poor road
surfaces.
The paper relates modes of failure to immediate operating
conditions and types of long-term service. As such, it offers
statistical methods for determining anticipated loading
requirements.