Seem 2-15 Failure criteria of prefabricated, corrugated steel, flexible arch-she?. > structures confined within non drag-sensitive earthwork configurations of . coral sand, simulating partially underground structures was studied. Three structures were tested in the 80 to 180 psi peak overpressure region from a 1.4 Mt surface shot to empirically determine the response of such structures. A fourth structure was tested in the 90 psi peak overpressure region froma 17 kt surface shot to determine the effects of short-—duration blast loading upon @ similar structure and environment. The 25-foot spzen by 48-foot, 10 gage archeshell structure subjected to 90 psi peak overpressure partially collapsed on the side away from ground zero, The collapse apparently was initiated by bearing failure of the shell plates at a bolted horizontal seam, approximately 5 feet above floor level on the collapsed side of the struc= ture. The following results have been noted on the other 3 structures: 1. A similar 25-foot span structure and the 38-foot span by 4C-foot 1 gage arch-shell structure, subjected respectively to 78 psi and 100 psi peek overpressure from shot Koa suffered a complete collapse symmetrically about the crown, The third 25-foot span structure subjected to a 180 psi peak overpressure collapsed completely. The dynamic behavior of deep (thick) reinforcec concrete slabs in the high overpressure regions of 175 to 600 psi was studied to provide the basis for establishing design criteria for massive reinforced concrete structures under blast loads. epid0e Un 1 B®. % Thirty one-way and fifteen two-way slabs placed flush with the ground surface were tested. The clear span was 6 feet and the ratios of depth to span varied from 0.15 to 0.78 Because of excessive post- shot radiation at the slab locations, data recovery has not been completed. eopleD/006 aah pier SS 1S —<