Reliability Model for Wood Structural Systems

Abstract

An approximate reliability model for wood structural systems is suggested. The model requires that the probability of first member failure be determined using a wood system model which includes partial composite and two‐way action. The proposed model can then be used to estimate ultimate capacity reliability from first member failure probability. System ultimate capacity is defined as failure of two adjacent members or failure of a set number of members, whichever occurs first. It is demonstrated that the use of first member failure as an ultimate limit state is not necessarily conservative. The level of the reliability with respect to the first failed member versus system reliability must be considered. The relationship between first member reliability and system reliability is an S‐curve. Some guidelines are suggested for determining safe levels of first member reliability as well as setting target reliability levels for use in development of a LRFD code.