The effect of test specimen out-of-roundness is included in the 

 empirically derived portions of the guides so use of the guides implicitly 

 assumes out-of-roundness of similar magnitude for the new structure. 

 This is a safe assumption because out-of-roundness criteria as given in 

 Table 1 and Table B-2 are lenient for large structures (in other words, 

 large structures should have better geometry control than the test 

 specimens) . 



Figure 3 is a design chart to predict implosion for thick- and 

 thin-walled concrete cylinder structures. A feature of the chart is its 

 simplicity. By knowing the t/D and L/D ratio of the structure, the 

 implosion strength in terms of P. /f can be determined. Implosion 

 pressure, P. , is calculated by assigning an f to the concrete. A 

 factor of safety is not included in the predicted implosion pressure. 



The design chart has application in sizing-out a structure for a 

 given depth . Advanced design techniques must be used to complete a 

 final design, but these techniques need to start from near-final dimen- 

 sions. This report provides the design charts to quickly determine the 

 near-final dimensions . 



CONCLUSIONS 



1 . Failure of concrete cylindrical structures under hydrostatic 

 loading can be described by one of three equations : an average wall 

 stress equation apphes to thick-walled cylinders; Donnell's equation to 

 moderately long, thin-walled cylinders; and Bresse's equation to long 

 thin-walled cylinders. An empirical parameter was used in each equa- 

 tion to obtain agreement between the experimental results and theoreti- 

 cal expression. 



2. The finite element analysis method with a constitutive material 

 model predicted the implosion strength and structural displacement 



23 



