Module 5 : Force Method - Introduction and applications
Lecture 3 : Analysis of Statically Indeterminate Structures by Energy Method

(ii)  When beam is flexible

 

The total energy stored in the beam

 
             
 

Span DG : ( x measured from D )

 

                         

                          
              
 

Span GE : ( x measured from D )

                         
                          
              
              
 

Span EF : ( x measured from F )

                          
                        
                        
  Thus,             
                                    
                                   
 

Total strain energy in the system

                      
  Hence,       
 
                                        
 

Since      

                                           
                                     
 
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