Statistical Combination of Extreme Loads

As most loads on buildings and structures are stochastic in nature, an analytical method for studying load combination is presented in which the loads are treated as random processes. Factors considered include load occurrence rate, intensity variation, duration of each occurrence, and simultaneous occurrence of different loads. The probability distribution of the maximum combined load effect over a given time interval is derived and the distribution parameters as functions of the first two moments and the occurrence rate of individual loads are also obtained in close form. Numerical examples are given and the results are compared satisfactorily with Monte-Carlo simulation. The reduction factors for load combination as given in current building codes are examined and their inadequacy pointed out.