Nonlinear Response to Sustained Load Processes

Abstract

Reliability analysis of structural members subjected to a stochastic load process is extended to include material nonlinearity. Characteristics of the nonlinear response are computed for a member with a bilinear force‐deformation relationship having the unloading range parallel to the initial elastic range. The expected number of loads exceeding a predetermined deformation level is derived for a Poisson load process with rectangular pulses. It is found that the derived values agree very well with those obtained from the simulated sustained load processes. The expected damage duration (the total time a process spends above the threshold deformation level) is also derived. For a square wave process, the derivation is theoretically exact once the expected number of exceedances is known.