COSMOS: Complete Online Solutions Manual Organization System
Chapter 3, Solution 126.
Have
ΣF : FB + FC + FD + FE = R
− ( 470 kips ) j − ( 66 kips ) j − ( 28 kips ) j − (116 kips ) j = R
∴ R = − ( 680 kips ) j
Have
ΣM x : FB ( z B ) + FC ( zC ) + FD ( z D ) + FE ( z E ) = R ( z B )
( 470 kips )( 48 ft ) + ( 66 kips )(18 ft ) + ( 28 kips )(100.5 ft ) + (116 kips )( b ) = ( 680 kips )( 48 ft )
∴ b = 52.397 ft or b = 52.4 ft
Have
ΣM z : FB ( xB ) + FC ( xC ) + FD ( xD ) + FE ( xE ) = R ( xB )
( 470 kips )( 96 ft ) + ( 66 kips )(162 ft ) + ( 28 kips )( 96 ft ) + (116 kips )( a ) = ( 680 kips )( 96 ft )
∴ a = 58.448 ft or a = 58.4 ft
.