Abstract: A functionally improved tape-like, heterogeneous, strip material for use in the fabrication of laminated structural shapes having high value of Young's Modulus and high tensile strength, comprising collocated, unidirectional, tectonic filaments such as graphite, boron, silicon-carbide, S-glass and E-glass, embodied in planar concourse, into an organic, thermosetting resin matrix or sheath such as an epoxy or polyimide base polymer forming a basal tract having at least one integral marginal tract of differing physical character so that a relatively lower Young's Modulus is exhibited by the material comprising the marginal tract than that exhibited by the basal tract. This difference in structural characteristic serves to provide an inherent arrestment barrier against fast rupture propagation of fractures which may develop in the basal tract material when the composite strip is subjected to sustained overload or external damage.