Five steps of force method:

Step 1: Define a released structure, define a coordinate system with sense, define matrix of required

actions with positive sense.

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Step 2: Determine displacements and required actions due to applied load cases on the released

structure.

This means find D1, D2, and D3 also find the required actions

,

Step 3: Turn by turn apply unit actions along the coordinates and determine displacements at all

coordinates. This gives the flexibility matrix . Also find the required actions due to unit loads

applied turn by turn which gives the matrix of actions due to unit loads .

,

Step 4: Solve the geometry or compatibility equation.

, where is the matrix of actions applied on the actual structure (applied actions

along the coordinates).

Step 5: Using equation of superposition determine the matrix of required actions .

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