Deniels [6] demonstrated that the asymptotic strength distribution of a parallel fiber bundle when the bundle size N is large enough is of normal type. This conclusion has been accepted by the latter studies. Harlow and Phoenix [7] proposed the concept of the chain-of-bundles model of the strength of fibrous structure to tackle the issue of statistical nature of strength of individual filament, the size ( length ) effect on filament strength as well as the load sharing mechanism during structure breakage. Phoenix [8] also extended their method to the analysis of twisted fiber bundles by incorporating the fiber helical paths into his model. However, exclusion of the effects of fiber interaction such as interfiber friCtion and lateral constraint in his model brings serious limits to his theory in terms of the applcability and accuracy Of Prediction