dear afreiden,
I've tried the clue that you've given me
I found N1=0,6P N2=0,3P N3=0,03P N4=0,07P
but the answer should be N1=0,4P N2=0,3P N3=0,2P N4=0,1P (according to the writer)
the writer said use the force method or displacement method or
the matrix stiffness method, any idea?