88 AN ANALYSIS OF TESTS OF WATER-TIGHT BUIvKHEADS. 



the deflections ordinarily considered permissible, the tension is generally 

 so small that it may be neglected, or, if it is desired to take it into account, 

 the tensional stress so found may be simply added to the stress dvie to 



pure bending. In fact, as long as o does not exceed about , the tension 



200 



will be less than one ton per square inch. (See table of stresses and deflec- 

 tions on page 12 and the numerical example given at the end of the 

 Appendix.) If in the design of new bulkheads we desire to examine the 

 value of the tension, we may with sufficient accuracy calculate the deflec- 

 tion for pure bending and use the value of S so found in the determination 

 of T. 



Only in extreme cases need we use the formulas for combined tension 

 and bending, but in view of the tension being determined independently, 

 as explained above, the treatment of the problem of a stiffener fixed at the 

 ends, which was given in last year's paper, has been somewhat modified 

 and extended in the Appendix of the present paper. 



In the case of uniform load it has been found possible altogether to 

 avoid the expansion of the exponential functions. In the case of uniform 

 plus increasing load such expansion is unavoidable, as a convenient solution 

 cannot otherwise be obtained, and it has been found necessary to extend 

 the expansion somewhat further than given in last year's paper in order 

 to obtain sufficient accuracy. 



II. Analysis of Bulkhead Tests. 



a. description of tests. 



The tests here analyzed were carried out on bulkheads of rectangular 

 form stiffened by a system of vertical, equidistant stifi'eners of uniform 

 section. This system is used in several navies, it has recently been adopted 

 by lyloyds and Veritas and has been used for some time by several other 

 Classification Societies; it is therefore of greater interest and importance 

 than any other system of stiffening. The tests fall in two classes, those 

 where the stift'eners are double, i. e., placed on both sides of the bulkhead, 

 as in Fig. 4, a, and those where the stiffeners are single, as in Fig. 4, b. 



n&.4. 



