Effect of Roof Load on Substantial Dividing Wall (SDW) Protection

摘要

The Naval Facilities Engineering Service Center (NAVFAC ESC) was tasked by the U.S. Department of Defense Explosive Safety Board (DDESB) to evaluate the effect of roof load on the protection provided by substantial dividing walls (SDW). The latest DDESB Substantial Dividing Wall (SDW) guidance memo (January 2003) allows the placement of up to 425 pounds of Sensitivity Group (SG) 1 through SG 4 explosives in a partial containment bay for siting purposes. The application of this SDW guidance includes a weight limit of 10 psf for all frangible surfaces. If one of the frangible surfaces is a roof, the memo requires consideration of the site specific snow load in calculating the roof's weight. In many areas of the U.S. the snow load is too high to allow the roof to be considered a frangible surface. In other areas, snow may not be present, but the actual roof weight may exceed 10 psf anyway. As a result, the SDW memo often cannot be applied and the SDWs must be analyzed according to criteria developed for the U.S. Navy High Performance Magazine Non-Propagation Wall. The resulting net explosive weight (NEW) limits are often too low to satisfy minimum operational requirements for preventing propagation of detonation. This paper examines the effect of additional roof loading using three storage facilities (described in Section 3.0) as examples. Roof loads between 10 psf and 40 psf are examined as well as charge weights up to 425 pounds.