Probabilistic Load Duration Model for Live Loads

Abstract

A stochastic model of the live load process in buildings provides a basis for the study of load duration. The combined load model is comprised of a sustained load process and multiple extraordinary load processes. Complete probability distributions of total time above a fixed reference load, duration of a single excursion upcrossing the reference load, and number of excursions for a fixed design lifetime are derived. These quantities are necessary for computing long‐term deflection and settlement of structures and critical load combinations for creep‐rupture materials, such as wood. The derived distributions are applied to several common building occupancy types. Results indicate the sensitivity of some duration characteristics to the extraordinary load and the need for even further refinement of the stochastic load process model.