Computer simulation was used to study the overload behavior of sheathe
d lumber systems. Simulations included in this study covered two-way a
ction of the sheathing; partial composite action between the sheathing
, connectors, and lumber members; the random mechanical properties of
the lumber members; and the random postyield properties of the partial
composite members. A trilinear spring model and a member-replacement
technique were introduced to account for the nonlinear behavior of par
tial composite members. The primary factors affecting system overload
behavior are the variation in the modulus of rupture of the lumber mem
bers and the three parameters that describe the postyield properties o
f the partial composite members. System-failure criteria are developed
and are related to the same factors. A distinction is made between br
ittle-member systems and nonbrittle-member systems. The results apply
for uniformly distributed loads applied to the system and do not inclu
de the effects of load duration.