It was learned that general-purpose blast doors designed to resist medium overpressures could be made from solid wood, plywood, sheet steel, and cellular steel sections. The door design criteria will be distributed to architects and engineers interested in designing lowcost blast-resistant doors. (See slide No. 27.) SLIDE No. 27.-Test prototype antiblast valve with weatherproof hood. To limit the pressure rise and consequent damage to equipment and injury to occupants, ventilating openings in a blast-resistant structure must be closed before or within a few milliseconds after the arrival of shock wave. For this purpose 11 prototype antiblast valves of various sizes were designed and tested. The valves were of the poppet type with the disk held in the open position by a spring and were actuated by blast overpressures. The valves were tested at pressures from 312 to 100 pounds per square inch. (See slide No. 28.) Although the valves operated safely, some design refinements will be made to improve the performance and the series of sizes will be extended. In a previous test series unfavorable and invalid comparisons were made between unreinforced brick masonry and reinforced concrete block. A reinforced brick windowless building located at the 5 pounds per square inch range, and 6 clay masonry wells placed at the 312 and 7 pounds per square inch range were tested. SLIDE No. 29.-Reinforced building which suffered no damage when exposed to over 5 pounds per square inch. Shown in slide No. 29 is the reinforced building which suffered no damage when exposed to over 5 pounds per square inch. You may recall that in a previous test a brick structure literally disintegrated at about 5 pounds per square inch. The results of the test indicate that unreinforced brick using the arching principle as well as reinforced brick masonry can develop considerable resistance to blast effects. (See slide No. 30.) Using the results of the test, a clay masonry design has been developed which will be both economical and resistant to lowblast overpressures. It is ideal to design into a shelter a dual purpose a mass shelter in a time of emergency and a functional purpose in peacetime. Slide No. 31 is a cutaway view of an underground parking garage and group shelter which FCDA had designed and tested. |