86 



AN ANALYSIS OF TESTS OF WATER-TIGHT BULKHEADS. 



FIG. 3. 



CURVES OF BCNDINa MOMENTS. 

 I. UNIFORM LOAD Jf 



ENDS FIXrD 

 CC'- 00'' DO' 

 AC - -0 9 I • BO 



USWER EMD nxtP 



UPPER EMC THIS 



CC' oo' 



AC ••Ota I 



As seen from the diagrams, equalization of the moments at C and D 

 with that at O is attained in all cases, when the brackets are of a height 

 equal to somewhat less than one-tenth of the length of the stiffener. 



It is clear, however, that the height of the brackets must be regulated 

 not only by the length but also by the strength of the stiffener. In case 

 of deck beams the same problem occurs, and practise has there fixed upon 

 a depth of knee or bracket of about three times the depth of the beam. 

 The same rule may be applied to the lower brackets of stiffeners, provided 

 that the bar is split and that its free flange with face plate or reversed 

 bar, if any, is carried out along the sloping (outstanding) edge of the bracket. 



The horizontal side of the bracket should likewise be of a length equal 

 to about three times the depth of the stiffener. 



The length of the sides of the upper bracket in a stiffener, which is 

 bracketed also at the foot, may be about ten per cent, less than in the 

 lower bracket. 



Referring to last year's paper, it was stated on page 391 of the Trans- 

 actions (1909) that when a stiffener is bracketed at the foot and freely 

 supported at the top, the maximum bending moment will be greater than 

 if the stiffener had been freely supported at both ends. This statement 

 requires qualification, for, as explained above, it is true only if the bracket- 

 ing is effected by connecting the stifl'ener to an absolutely rigid floor plate 

 or longitudinal as shown in Fig. i, a, instead of simply attaching it to the 

 top of the floors as in Fig. 1, d. It is not true if an effective bracket is 

 fitted above the floors as in Fig. i , h and c. 



In Table II of the Report of the British Bulkhead Committee of 1890 



