206 



Mr. 0. H. Lander on Struts and Tie-Rodt 



diagrams should be subtracted from the lateral load bending 

 moment diagram, but otherwise the process remains exactly 

 as before. 



Encastre and Continuous Beams. — The method may be 

 applied to the solution of encastre and continuous beams. 

 The curve, however, into which the beam bends under both 

 lateral and endlong loads does not, as in the case of free- 

 ended or discontinuous beams, accurately represent the 

 shape of the bending moment diagram for the end load. 

 The fixing moments at the supports alter the base-line from 

 which moments must be measured, and in general result in 

 diminishing the moments due to the primary deflexion 

 diagram. It is therefore even less necessary to consider the 

 secondary deflexion effects than was the case with the free- 

 ended beam- 

 Consider the case of the encastre beam under a regular 

 system of loads and with an endlong load P applied along 

 the neutral axis. Since the tangents at the extremities of 

 such a beam are horizontal and therefore parallel to one 

 another, the total area of the bending moment diagram 

 between these two points must be zero, and this condition 

 must apply to all bending moment diagrams drawn, 



W 



P 



Be/?a7/ia /770we/7/ c/Zapra??? 

 for facte/ w o/?/y. 



Def/ocforL d/ayra??? for load PV <mfy. 



causeo/ f?y /?r/>?7ary afef/ecfio/i. 



whether due to the lateral system only or to the diagrams 

 obtained from the primary or secondary deflexion corves. 

 Starting therefore from a bending moment diagram, fig. 2, 



