84 



AN ANALYSIS OF TESTS OF WATER-TIGHT BULKHEADS. 



to end at B and to be strictly vertical at this point. The stiffener is then 

 at B subject to the entire bending moment BS without any reinforcement 

 in strength at this point. 



na. I . 



Af INOICATCS CURVE OF 6ENDlN<i MOMENTS. 



We shall now consider the more ordinary case where a triangular 

 bracket is fitted, and we shall assume that the main bar of the stiffener 

 is held so that its end is strictly vertical, i. e., so that perfect encastrement 

 is attained, and that the structural element of the hull, to which the bracket 

 is attached, is perfectly rigid. We must here take account of the facts, 

 firstly, that the supporting forces exerted by the bracket are applied at 

 some distance from the end of the bar, and, secondly, that when the bracket 

 is intimately connected with the stiffener, it serves to reinforce the stiffener 

 structurally by increasing its moment of inertia. 



Let us consider separately the two forms of brackets illustrated on 

 Fig. I, b and c. 



The bracket shown on Fig. i, b, may be considered to be quite inde- 

 pendent of the bar of the stiffener, i. c, as a more or less rigid fixture to 

 which the bar is connected, but which does not reinforce it. The effective 

 height of the bracket is in this case not FB but FB', the overlap of the 

 bracket on the bar, since no increase in the height of the bracket would 

 increase its hold on the stiffener as long as this overlap remains the same. 

 Evidently there can be no bending moment at the end of the stiffener or 

 even at the lowest rivet. The supporting force, instead of being applied 

 at the end of the stiffener, as generally assumed in the theoretical treatment 

 of this problem, is actually subdivided in minor forces, applied at the vari- 

 ous rivets on the overlap, and these forces will greatly affect the bending 

 moments to which the stiffener proper is subject between F and B'. Refer- 

 ring to Fig. 1,6, the curve of bending moments, instead of being continued 

 to the point S, as generally assumed, will reach a maximum a little below 



