Rollover protective structure and method

A rollover protective structure (ROPS) for use with construction machinery includes a two-post frame having upright posts attached between a base and canopy and cross members attached between the posts. The posts are constructed from a pair of angled post members to define a box-like cross-section for the posts. The posts have rounded interior corners and square interior corners between adjacent sides thereof. Reinforcing members are attached between the adjacent sides and across the rounded interior corners to uniformly stiffen the post. Additionally, reinforcing members are attached between the base and upright posts to reinforce the intersection thereof. The reinforcing members include an upper portion attached between the post and base and a lower portion attached between the upper portion and base. The upper portion and the lower portion are constructed to collapse sequentially to maintain resistance to additional load deformation as the rollover protective structure is deformed.