an efficient structural composite suitable for a cantilever applications in nonomnidirectional uses , such as that of highway guardrail posts , assembled from recycled plastic or rubber material as compressive elements with embedded formed sheet steel as tensile elements and shear transfer by encapsulation of said tensile elements in said compressive elements . structural integrity and / or specific maximum service loads can be achieved through design sizing of shear - transfer elements allowing for intended catastrophic structural failure , which is useful in highway guardrail system design .