5003 Lectures - Faculty of Engineering and Applied Science

E5003 - Ship Structures I 131
© C.G. Daley
Step 2: plan the solution strategy and determine if
the structure will sway
In the standard type of problem the joints do not
translate, they only rotate. Axial and shear
deformations are ignored. Only bending
deformations are considered. If the model supports
permit one or more joints to translate, and the
load is such that it will cause such a movement,
we need to consider sway. The example structures
at the left show both types (no-sway and sway).
Note: And 'imposed' joint movement, as would
occur when a support 'settles' a fixed amount, is
not a sway problem. Imposed movements are just
as easy to solve as are applied loads.
In cases where there are redundant parts of the
structure (a determinant sub-structure), such as
cantilever portions as shown at left, these should
be removed and replaced with the moments or
forces that they cause on the remaining structure.
Step 3: Find moment distribution factors α :
For each joint we find the set of moment
distribution factors. In general;