Combination of Various Load Processes

A method for computing the probability distribution of combined, time varying loading on a structure is presented. The point crossing method is based on finding a close upper bound to the mean upcrossing rate of a linear combination of scalar load processes. Both smooth, continuous processes and pulse-type processes are included. The solution is a series of single convolutions of two natural descriptors of the load effect process: the first-order or arbitrary-point-in-time probability distribution and the mean upcrossing rate function. An example of the combination of three load processes is included, and the method is compared with others. Implications for load modeling and a format for combined loads in deterministic design codes are analyzed.