a preferred embodiment or staggered the overall cribbing structure is constructed similarly to conventional wooden cribbing structure and that is by stacking crib elements the cribbing structure is tightened between the roof and floor or hanging wall and footwall through steel inserts wedges grout bags wooden wedges or other suitable materials which have high rigidity and will not shrink thus a high preload can be applied to the crib during its construction process preferably the material used for the wedges has a similar stiffness to the load carrying member to apply a maximum preload to the constructed steel crib structure in preferred embodiments the wedges are constructed of steel and are 3 inches wide to 5 inches wide to keep their weight to a minimum other sizes and materials for tightening the crib are within the scope of this invention the steel wedges or inserts can also be manufactured from hollow steel tube the embodiments of the present invention are best described in reference to the figures the crib element embodied in fig1 is constructed of two 6 inch u00d7 6 inch u00d7 6 inch pieces of solid steel as the load carrying structural members 22 these load carrying structural members 22 are connected through an elongate.